Merge branch 'kvm-tsx-ctrl' into HEAD

Conflicts:
	arch/x86/kvm/vmx/vmx.c

26 files changed, 746 insertions, 87 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 06d0931119cc..fc20cde63d1e 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -486,6 +486,8 @@ What:		/sys/devices/system/cpu/vulnerabilities
 		/sys/devices/system/cpu/vulnerabilities/spec_store_bypass
 		/sys/devices/system/cpu/vulnerabilities/l1tf
 		/sys/devices/system/cpu/vulnerabilities/mds
+		/sys/devices/system/cpu/vulnerabilities/tsx_async_abort
+		/sys/devices/system/cpu/vulnerabilities/itlb_multihit
 Date:		January 2018
 Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
 Description:	Information about CPU vulnerabilities
diff --git a/Documentation/admin-guide/hw-vuln/index.rst b/Documentation/admin-guide/hw-vuln/index.rst
index 49311f3da6f2..0795e3c2643f 100644
--- a/Documentation/admin-guide/hw-vuln/index.rst
+++ b/Documentation/admin-guide/hw-vuln/index.rst
@@ -12,3 +12,5 @@ are configurable at compile, boot or run time.
    spectre
    l1tf
    mds
+   tsx_async_abort
+   multihit.rst
diff --git a/Documentation/admin-guide/hw-vuln/multihit.rst b/Documentation/admin-guide/hw-vuln/multihit.rst
new file mode 100644
index 000000000000..ba9988d8bce5
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/multihit.rst
@@ -0,0 +1,163 @@
+iTLB multihit
+=============
+
+iTLB multihit is an erratum where some processors may incur a machine check
+error, possibly resulting in an unrecoverable CPU lockup, when an
+instruction fetch hits multiple entries in the instruction TLB. This can
+occur when the page size is changed along with either the physical address
+or cache type. A malicious guest running on a virtualized system can
+exploit this erratum to perform a denial of service attack.
+
+
+Affected processors
+-------------------
+
+Variations of this erratum are present on most Intel Core and Xeon processor
+models. The erratum is not present on:
+
+   - non-Intel processors
+
+   - Some Atoms (Airmont, Bonnell, Goldmont, GoldmontPlus, Saltwell, Silvermont)
+
+   - Intel processors that have the PSCHANGE_MC_NO bit set in the
+     IA32_ARCH_CAPABILITIES MSR.
+
+
+Related CVEs
+------------
+
+The following CVE entry is related to this issue:
+
+   ==============  =================================================
+   CVE-2018-12207  Machine Check Error Avoidance on Page Size Change
+   ==============  =================================================
+
+
+Problem
+-------
+
+Privileged software, including OS and virtual machine managers (VMM), are in
+charge of memory management. A key component in memory management is the control
+of the page tables. Modern processors use virtual memory, a technique that creates
+the illusion of a very large memory for processors. This virtual space is split
+into pages of a given size. Page tables translate virtual addresses to physical
+addresses.
+
+To reduce latency when performing a virtual to physical address translation,
+processors include a structure, called TLB, that caches recent translations.
+There are separate TLBs for instruction (iTLB) and data (dTLB).
+
+Under this errata, instructions are fetched from a linear address translated
+using a 4 KB translation cached in the iTLB. Privileged software modifies the
+paging structure so that the same linear address using large page size (2 MB, 4
+MB, 1 GB) with a different physical address or memory type.  After the page
+structure modification but before the software invalidates any iTLB entries for
+the linear address, a code fetch that happens on the same linear address may
+cause a machine-check error which can result in a system hang or shutdown.
+
+
+Attack scenarios
+----------------
+
+Attacks against the iTLB multihit erratum can be mounted from malicious
+guests in a virtualized system.
+
+
+iTLB multihit system information
+--------------------------------
+
+The Linux kernel provides a sysfs interface to enumerate the current iTLB
+multihit status of the system:whether the system is vulnerable and which
+mitigations are active. The relevant sysfs file is:
+
+/sys/devices/system/cpu/vulnerabilities/itlb_multihit
+
+The possible values in this file are:
+
+.. list-table::
+
+     * - Not affected
+       - The processor is not vulnerable.
+     * - KVM: Mitigation: Split huge pages
+       - Software changes mitigate this issue.
+     * - KVM: Vulnerable
+       - The processor is vulnerable, but no mitigation enabled
+
+
+Enumeration of the erratum
+--------------------------------
+
+A new bit has been allocated in the IA32_ARCH_CAPABILITIES (PSCHANGE_MC_NO) msr
+and will be set on CPU's which are mitigated against this issue.
+
+   =======================================   ===========   ===============================
+   IA32_ARCH_CAPABILITIES MSR                Not present   Possibly vulnerable,check model
+   IA32_ARCH_CAPABILITIES[PSCHANGE_MC_NO]    '0'           Likely vulnerable,check model
+   IA32_ARCH_CAPABILITIES[PSCHANGE_MC_NO]    '1'           Not vulnerable
+   =======================================   ===========   ===============================
+
+
+Mitigation mechanism
+-------------------------
+
+This erratum can be mitigated by restricting the use of large page sizes to
+non-executable pages.  This forces all iTLB entries to be 4K, and removes
+the possibility of multiple hits.
+
+In order to mitigate the vulnerability, KVM initially marks all huge pages
+as non-executable. If the guest attempts to execute in one of those pages,
+the page is broken down into 4K pages, which are then marked executable.
+
+If EPT is disabled or not available on the host, KVM is in control of TLB
+flushes and the problematic situation cannot happen.  However, the shadow
+EPT paging mechanism used by nested virtualization is vulnerable, because
+the nested guest can trigger multiple iTLB hits by modifying its own
+(non-nested) page tables.  For simplicity, KVM will make large pages
+non-executable in all shadow paging modes.
+
+Mitigation control on the kernel command line and KVM - module parameter
+------------------------------------------------------------------------
+
+The KVM hypervisor mitigation mechanism for marking huge pages as
+non-executable can be controlled with a module parameter "nx_huge_pages=".
+The kernel command line allows to control the iTLB multihit mitigations at
+boot time with the option "kvm.nx_huge_pages=".
+
+The valid arguments for these options are:
+
+  ==========  ================================================================
+  force       Mitigation is enabled. In this case, the mitigation implements
+              non-executable huge pages in Linux kernel KVM module. All huge
+              pages in the EPT are marked as non-executable.
+              If a guest attempts to execute in one of those pages, the page is
+              broken down into 4K pages, which are then marked executable.
+
+  off	      Mitigation is disabled.
+
+  auto        Enable mitigation only if the platform is affected and the kernel
+              was not booted with the "mitigations=off" command line parameter.
+	      This is the default option.
+  ==========  ================================================================
+
+
+Mitigation selection guide
+--------------------------
+
+1. No virtualization in use
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   The system is protected by the kernel unconditionally and no further
+   action is required.
+
+2. Virtualization with trusted guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   If the guest comes from a trusted source, you may assume that the guest will
+   not attempt to maliciously exploit these errata and no further action is
+   required.
+
+3. Virtualization with untrusted guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   If the guest comes from an untrusted source, the guest host kernel will need
+   to apply iTLB multihit mitigation via the kernel command line or kvm
+   module parameter.
diff --git a/Documentation/admin-guide/hw-vuln/tsx_async_abort.rst b/Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
new file mode 100644
index 000000000000..fddbd7579c53
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
@@ -0,0 +1,276 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+TAA - TSX Asynchronous Abort
+======================================
+
+TAA is a hardware vulnerability that allows unprivileged speculative access to
+data which is available in various CPU internal buffers by using asynchronous
+aborts within an Intel TSX transactional region.
+
+Affected processors
+-------------------
+
+This vulnerability only affects Intel processors that support Intel
+Transactional Synchronization Extensions (TSX) when the TAA_NO bit (bit 8)
+is 0 in the IA32_ARCH_CAPABILITIES MSR.  On processors where the MDS_NO bit
+(bit 5) is 0 in the IA32_ARCH_CAPABILITIES MSR, the existing MDS mitigations
+also mitigate against TAA.
+
+Whether a processor is affected or not can be read out from the TAA
+vulnerability file in sysfs. See :ref:`tsx_async_abort_sys_info`.
+
+Related CVEs
+------------
+
+The following CVE entry is related to this TAA issue:
+
+   ==============  =====  ===================================================
+   CVE-2019-11135  TAA    TSX Asynchronous Abort (TAA) condition on some
+                          microprocessors utilizing speculative execution may
+                          allow an authenticated user to potentially enable
+                          information disclosure via a side channel with
+                          local access.
+   ==============  =====  ===================================================
+
+Problem
+-------
+
+When performing store, load or L1 refill operations, processors write
+data into temporary microarchitectural structures (buffers). The data in
+those buffers can be forwarded to load operations as an optimization.
+
+Intel TSX is an extension to the x86 instruction set architecture that adds
+hardware transactional memory support to improve performance of multi-threaded
+software. TSX lets the processor expose and exploit concurrency hidden in an
+application due to dynamically avoiding unnecessary synchronization.
+
+TSX supports atomic memory transactions that are either committed (success) or
+aborted. During an abort, operations that happened within the transactional region
+are rolled back. An asynchronous abort takes place, among other options, when a
+different thread accesses a cache line that is also used within the transactional
+region when that access might lead to a data race.
+
+Immediately after an uncompleted asynchronous abort, certain speculatively
+executed loads may read data from those internal buffers and pass it to dependent
+operations. This can be then used to infer the value via a cache side channel
+attack.
+
+Because the buffers are potentially shared between Hyper-Threads cross
+Hyper-Thread attacks are possible.
+
+The victim of a malicious actor does not need to make use of TSX. Only the
+attacker needs to begin a TSX transaction and raise an asynchronous abort
+which in turn potenitally leaks data stored in the buffers.
+
+More detailed technical information is available in the TAA specific x86
+architecture section: :ref:`Documentation/x86/tsx_async_abort.rst <tsx_async_abort>`.
+
+
+Attack scenarios
+----------------
+
+Attacks against the TAA vulnerability can be implemented from unprivileged
+applications running on hosts or guests.
+
+As for MDS, the attacker has no control over the memory addresses that can
+be leaked. Only the victim is responsible for bringing data to the CPU. As
+a result, the malicious actor has to sample as much data as possible and
+then postprocess it to try to infer any useful information from it.
+
+A potential attacker only has read access to the data. Also, there is no direct
+privilege escalation by using this technique.
+
+
+.. _tsx_async_abort_sys_info:
+
+TAA system information
+-----------------------
+
+The Linux kernel provides a sysfs interface to enumerate the current TAA status
+of mitigated systems. The relevant sysfs file is:
+
+/sys/devices/system/cpu/vulnerabilities/tsx_async_abort
+
+The possible values in this file are:
+
+.. list-table::
+
+   * - 'Vulnerable'
+     - The CPU is affected by this vulnerability and the microcode and kernel mitigation are not applied.
+   * - 'Vulnerable: Clear CPU buffers attempted, no microcode'
+     - The system tries to clear the buffers but the microcode might not support the operation.
+   * - 'Mitigation: Clear CPU buffers'
+     - The microcode has been updated to clear the buffers. TSX is still enabled.
+   * - 'Mitigation: TSX disabled'
+     - TSX is disabled.
+   * - 'Not affected'
+     - The CPU is not affected by this issue.
+
+.. _ucode_needed:
+
+Best effort mitigation mode
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If the processor is vulnerable, but the availability of the microcode-based
+mitigation mechanism is not advertised via CPUID the kernel selects a best
+effort mitigation mode.  This mode invokes the mitigation instructions
+without a guarantee that they clear the CPU buffers.
+
+This is done to address virtualization scenarios where the host has the
+microcode update applied, but the hypervisor is not yet updated to expose the
+CPUID to the guest. If the host has updated microcode the protection takes
+effect; otherwise a few CPU cycles are wasted pointlessly.
+
+The state in the tsx_async_abort sysfs file reflects this situation
+accordingly.
+
+
+Mitigation mechanism
+--------------------
+
+The kernel detects the affected CPUs and the presence of the microcode which is
+required. If a CPU is affected and the microcode is available, then the kernel
+enables the mitigation by default.
+
+
+The mitigation can be controlled at boot time via a kernel command line option.
+See :ref:`taa_mitigation_control_command_line`.
+
+.. _virt_mechanism:
+
+Virtualization mitigation
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Affected systems where the host has TAA microcode and TAA is mitigated by
+having disabled TSX previously, are not vulnerable regardless of the status
+of the VMs.
+
+In all other cases, if the host either does not have the TAA microcode or
+the kernel is not mitigated, the system might be vulnerable.
+
+
+.. _taa_mitigation_control_command_line:
+
+Mitigation control on the kernel command line
+---------------------------------------------
+
+The kernel command line allows to control the TAA mitigations at boot time with
+the option "tsx_async_abort=". The valid arguments for this option are:
+
+  ============  =============================================================
+  off		This option disables the TAA mitigation on affected platforms.
+                If the system has TSX enabled (see next parameter) and the CPU
+                is affected, the system is vulnerable.
+
+  full	        TAA mitigation is enabled. If TSX is enabled, on an affected
+                system it will clear CPU buffers on ring transitions. On
+                systems which are MDS-affected and deploy MDS mitigation,
+                TAA is also mitigated. Specifying this option on those
+                systems will have no effect.
+
+  full,nosmt    The same as tsx_async_abort=full, with SMT disabled on
+                vulnerable CPUs that have TSX enabled. This is the complete
+                mitigation. When TSX is disabled, SMT is not disabled because
+                CPU is not vulnerable to cross-thread TAA attacks.
+  ============  =============================================================
+
+Not specifying this option is equivalent to "tsx_async_abort=full".
+
+The kernel command line also allows to control the TSX feature using the
+parameter "tsx=" on CPUs which support TSX control. MSR_IA32_TSX_CTRL is used
+to control the TSX feature and the enumeration of the TSX feature bits (RTM
+and HLE) in CPUID.
+
+The valid options are:
+
+  ============  =============================================================
+  off		Disables TSX on the system.
+
+                Note that this option takes effect only on newer CPUs which are
+                not vulnerable to MDS, i.e., have MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1
+                and which get the new IA32_TSX_CTRL MSR through a microcode
+                update. This new MSR allows for the reliable deactivation of
+                the TSX functionality.
+
+  on		Enables TSX.
+
+                Although there are mitigations for all known security
+                vulnerabilities, TSX has been known to be an accelerator for
+                several previous speculation-related CVEs, and so there may be
+                unknown security risks associated with leaving it enabled.
+
+  auto		Disables TSX if X86_BUG_TAA is present, otherwise enables TSX
+                on the system.
+  ============  =============================================================
+
+Not specifying this option is equivalent to "tsx=off".
+
+The following combinations of the "tsx_async_abort" and "tsx" are possible. For
+affected platforms tsx=auto is equivalent to tsx=off and the result will be:
+
+  =========  ==========================   =========================================
+  tsx=on     tsx_async_abort=full         The system will use VERW to clear CPU
+                                          buffers. Cross-thread attacks are still
+					  possible on SMT machines.
+  tsx=on     tsx_async_abort=full,nosmt   As above, cross-thread attacks on SMT
+                                          mitigated.
+  tsx=on     tsx_async_abort=off          The system is vulnerable.
+  tsx=off    tsx_async_abort=full         TSX might be disabled if microcode
+                                          provides a TSX control MSR. If so,
+					  system is not vulnerable.
+  tsx=off    tsx_async_abort=full,nosmt   Ditto
+  tsx=off    tsx_async_abort=off          ditto
+  =========  ==========================   =========================================
+
+
+For unaffected platforms "tsx=on" and "tsx_async_abort=full" does not clear CPU
+buffers.  For platforms without TSX control (MSR_IA32_ARCH_CAPABILITIES.MDS_NO=0)
+"tsx" command line argument has no effect.
+
+For the affected platforms below table indicates the mitigation status for the
+combinations of CPUID bit MD_CLEAR and IA32_ARCH_CAPABILITIES MSR bits MDS_NO
+and TSX_CTRL_MSR.
+
+  =======  =========  =============  ========================================
+  MDS_NO   MD_CLEAR   TSX_CTRL_MSR   Status
+  =======  =========  =============  ========================================
+    0          0            0        Vulnerable (needs microcode)
+    0          1            0        MDS and TAA mitigated via VERW
+    1          1            0        MDS fixed, TAA vulnerable if TSX enabled
+                                     because MD_CLEAR has no meaning and
+                                     VERW is not guaranteed to clear buffers
+    1          X            1        MDS fixed, TAA can be mitigated by
+                                     VERW or TSX_CTRL_MSR
+  =======  =========  =============  ========================================
+
+Mitigation selection guide
+--------------------------
+
+1. Trusted userspace and guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If all user space applications are from a trusted source and do not execute
+untrusted code which is supplied externally, then the mitigation can be
+disabled. The same applies to virtualized environments with trusted guests.
+
+
+2. Untrusted userspace and guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If there are untrusted applications or guests on the system, enabling TSX
+might allow a malicious actor to leak data from the host or from other
+processes running on the same physical core.
+
+If the microcode is available and the TSX is disabled on the host, attacks
+are prevented in a virtualized environment as well, even if the VMs do not
+explicitly enable the mitigation.
+
+
+.. _taa_default_mitigations:
+
+Default mitigations
+-------------------
+
+The kernel's default action for vulnerable processors is:
+
+  - Deploy TSX disable mitigation (tsx_async_abort=full tsx=off).
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 19f465530e86..9b847f06cb19 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2055,6 +2055,25 @@
 			KVM MMU at runtime.
 			Default is 0 (off)
 
+	kvm.nx_huge_pages=
+			[KVM] Controls the software workaround for the
+			X86_BUG_ITLB_MULTIHIT bug.
+			force	: Always deploy workaround.
+			off	: Never deploy workaround.
+			auto    : Deploy workaround based on the presence of
+				  X86_BUG_ITLB_MULTIHIT.
+
+			Default is 'auto'.
+
+			If the software workaround is enabled for the host,
+			guests do need not to enable it for nested guests.
+
+	kvm.nx_huge_pages_recovery_ratio=
+			[KVM] Controls how many 4KiB pages are periodically zapped
+			back to huge pages.  0 disables the recovery, otherwise if
+			the value is N KVM will zap 1/Nth of the 4KiB pages every
+			minute.  The default is 60.
+
 	kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.
 			Default is 1 (enabled)
 
@@ -2636,6 +2655,13 @@
 					       ssbd=force-off [ARM64]
 					       l1tf=off [X86]
 					       mds=off [X86]
+					       tsx_async_abort=off [X86]
+					       kvm.nx_huge_pages=off [X86]
+
+				Exceptions:
+					       This does not have any effect on
+					       kvm.nx_huge_pages when
+					       kvm.nx_huge_pages=force.
 
 			auto (default)
 				Mitigate all CPU vulnerabilities, but leave SMT
@@ -2651,6 +2677,7 @@
 				be fully mitigated, even if it means losing SMT.
 				Equivalent to: l1tf=flush,nosmt [X86]
 					       mds=full,nosmt [X86]
+					       tsx_async_abort=full,nosmt [X86]
 
 	mminit_loglevel=
 			[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
@@ -4848,6 +4875,71 @@
 			interruptions from clocksource watchdog are not
 			acceptable).
 
+	tsx=		[X86] Control Transactional Synchronization
+			Extensions (TSX) feature in Intel processors that
+			support TSX control.
+
+			This parameter controls the TSX feature. The options are:
+
+			on	- Enable TSX on the system. Although there are
+				mitigations for all known security vulnerabilities,
+				TSX has been known to be an accelerator for
+				several previous speculation-related CVEs, and
+				so there may be unknown	security risks associated
+				with leaving it enabled.
+
+			off	- Disable TSX on the system. (Note that this
+				option takes effect only on newer CPUs which are
+				not vulnerable to MDS, i.e., have
+				MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1 and which get
+				the new IA32_TSX_CTRL MSR through a microcode
+				update. This new MSR allows for the reliable
+				deactivation of the TSX functionality.)
+
+			auto	- Disable TSX if X86_BUG_TAA is present,
+				  otherwise enable TSX on the system.
+
+			Not specifying this option is equivalent to tsx=off.
+
+			See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
+			for more details.
+
+	tsx_async_abort= [X86,INTEL] Control mitigation for the TSX Async
+			Abort (TAA) vulnerability.
+
+			Similar to Micro-architectural Data Sampling (MDS)
+			certain CPUs that support Transactional
+			Synchronization Extensions (TSX) are vulnerable to an
+			exploit against CPU internal buffers which can forward
+			information to a disclosure gadget under certain
+			conditions.
+
+			In vulnerable processors, the speculatively forwarded
+			data can be used in a cache side channel attack, to
+			access data to which the attacker does not have direct
+			access.
+
+			This parameter controls the TAA mitigation.  The
+			options are:
+
+			full       - Enable TAA mitigation on vulnerable CPUs
+				     if TSX is enabled.
+
+			full,nosmt - Enable TAA mitigation and disable SMT on
+				     vulnerable CPUs. If TSX is disabled, SMT
+				     is not disabled because CPU is not
+				     vulnerable to cross-thread TAA attacks.
+			off        - Unconditionally disable TAA mitigation
+
+			Not specifying this option is equivalent to
+			tsx_async_abort=full.  On CPUs which are MDS affected
+			and deploy MDS mitigation, TAA mitigation is not
+			required and doesn't provide any additional
+			mitigation.
+
+			For details see:
+			Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
+
 	turbografx.map[2|3]=	[HW,JOY]
 			TurboGraFX parallel port interface
 			Format:
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index ab7ed2fd072f..5a09661330fc 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -91,6 +91,11 @@ stable kernels.
 | ARM            | MMU-500         | #841119,826419  | N/A                         |
 +----------------+-----------------+-----------------+-----------------------------+
 +----------------+-----------------+-----------------+-----------------------------+
+| Broadcom       | Brahma-B53      | N/A             | ARM64_ERRATUM_845719        |
++----------------+-----------------+-----------------+-----------------------------+
+| Broadcom       | Brahma-B53      | N/A             | ARM64_ERRATUM_843419        |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
 | Cavium         | ThunderX ITS    | #22375,24313    | CAVIUM_ERRATUM_22375        |
 +----------------+-----------------+-----------------+-----------------------------+
 | Cavium         | ThunderX ITS    | #23144          | CAVIUM_ERRATUM_23144        |
@@ -126,7 +131,7 @@ stable kernels.
 +----------------+-----------------+-----------------+-----------------------------+
 | Qualcomm Tech. | Kryo/Falkor v1  | E1003           | QCOM_FALKOR_ERRATUM_1003    |
 +----------------+-----------------+-----------------+-----------------------------+
-| Qualcomm Tech. | Falkor v1       | E1009           | QCOM_FALKOR_ERRATUM_1009    |
+| Qualcomm Tech. | Kryo/Falkor v1  | E1009           | QCOM_FALKOR_ERRATUM_1009    |
 +----------------+-----------------+-----------------+-----------------------------+
 | Qualcomm Tech. | QDF2400 ITS     | E0065           | QCOM_QDF2400_ERRATUM_0065   |
 +----------------+-----------------+-----------------+-----------------------------+
diff --git a/Documentation/devicetree/bindings/arm/rockchip.yaml b/Documentation/devicetree/bindings/arm/rockchip.yaml
index c82c5e57d44c..9c7e70335ac0 100644
--- a/Documentation/devicetree/bindings/arm/rockchip.yaml
+++ b/Documentation/devicetree/bindings/arm/rockchip.yaml
@@ -496,12 +496,12 @@ properties:
 
       - description: Theobroma Systems RK3368-uQ7 with Haikou baseboard
         items:
-          - const: tsd,rk3368-uq7-haikou
+          - const: tsd,rk3368-lion-haikou
           - const: rockchip,rk3368
 
       - description: Theobroma Systems RK3399-Q7 with Haikou baseboard
         items:
-          - const: tsd,rk3399-q7-haikou
+          - const: tsd,rk3399-puma-haikou
           - const: rockchip,rk3399
 
       - description: Tronsmart Orion R68 Meta
diff --git a/Documentation/devicetree/bindings/media/allwinner,sun4i-a10-csi.yaml b/Documentation/devicetree/bindings/media/allwinner,sun4i-a10-csi.yaml
index 27f38eed389e..d3e423fcb6c2 100644
--- a/Documentation/devicetree/bindings/media/allwinner,sun4i-a10-csi.yaml
+++ b/Documentation/devicetree/bindings/media/allwinner,sun4i-a10-csi.yaml
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
 %YAML 1.2
 ---
-$id: http://devicetree.org/schemas/arm/allwinner,sun4i-a10-csi.yaml#
+$id: http://devicetree.org/schemas/media/allwinner,sun4i-a10-csi.yaml#
 $schema: http://devicetree.org/meta-schemas/core.yaml#
 
 title: Allwinner A10 CMOS Sensor Interface (CSI) Device Tree Bindings
@@ -27,14 +27,12 @@ properties:
   clocks:
     items:
       - description: The CSI interface clock
-      - description: The CSI module clock
       - description: The CSI ISP clock
       - description: The CSI DRAM clock
 
   clock-names:
     items:
       - const: bus
-      - const: mod
       - const: isp
       - const: ram
 
@@ -89,9 +87,8 @@ examples:
         compatible = "allwinner,sun7i-a20-csi0";
         reg = <0x01c09000 0x1000>;
         interrupts = <GIC_SPI 42 IRQ_TYPE_LEVEL_HIGH>;
-        clocks = <&ccu CLK_AHB_CSI0>, <&ccu CLK_CSI0>,
-                 <&ccu CLK_CSI_SCLK>, <&ccu CLK_DRAM_CSI0>;
-        clock-names = "bus", "mod", "isp", "ram";
+        clocks = <&ccu CLK_AHB_CSI0>, <&ccu CLK_CSI_SCLK>, <&ccu CLK_DRAM_CSI0>;
+        clock-names = "bus", "isp", "ram";
         resets = <&ccu RST_CSI0>;
 
         port {
diff --git a/Documentation/devicetree/bindings/regulator/fixed-regulator.yaml b/Documentation/devicetree/bindings/regulator/fixed-regulator.yaml
index a78150c47aa2..f32416968197 100644
--- a/Documentation/devicetree/bindings/regulator/fixed-regulator.yaml
+++ b/Documentation/devicetree/bindings/regulator/fixed-regulator.yaml
@@ -30,8 +30,8 @@ if:
 properties:
   compatible:
     enum:
-      - const: regulator-fixed
-      - const: regulator-fixed-clock
+      - regulator-fixed
+      - regulator-fixed-clock
 
   regulator-name: true
 
diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
index b261a3015f84..04819ad379c2 100644
--- a/Documentation/devicetree/bindings/riscv/cpus.yaml
+++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
@@ -24,15 +24,17 @@ description: |
 
 properties:
   compatible:
-    items:
-      - enum:
-          - sifive,rocket0
-          - sifive,e5
-          - sifive,e51
-          - sifive,u54-mc
-          - sifive,u54
-          - sifive,u5
-      - const: riscv
+    oneOf:
+      - items:
+          - enum:
+              - sifive,rocket0
+              - sifive,e5
+              - sifive,e51
+              - sifive,u54-mc
+              - sifive,u54
+              - sifive,u5
+          - const: riscv
+      - const: riscv    # Simulator only
     description:
       Identifies that the hart uses the RISC-V instruction set
       and identifies the type of the hart.
@@ -66,12 +68,8 @@ properties:
       insensitive, letters in the riscv,isa string must be all
       lowercase to simplify parsing.
 
-  timebase-frequency:
-    type: integer
-    minimum: 1
-    description:
-      Specifies the clock frequency of the system timer in Hz.
-      This value is common to all harts on a single system image.
+  # RISC-V requires 'timebase-frequency' in /cpus, so disallow it here
+  timebase-frequency: false
 
   interrupt-controller:
     type: object
@@ -93,7 +91,6 @@ properties:
 
 required:
   - riscv,isa
-  - timebase-frequency
   - interrupt-controller
 
 examples:
diff --git a/Documentation/networking/device_drivers/intel/e100.rst b/Documentation/networking/device_drivers/intel/e100.rst
index 2b9f4887beda..caf023cc88de 100644
--- a/Documentation/networking/device_drivers/intel/e100.rst
+++ b/Documentation/networking/device_drivers/intel/e100.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-==============================================================
-Linux* Base Driver for the Intel(R) PRO/100 Family of Adapters
-==============================================================
+=============================================================
+Linux Base Driver for the Intel(R) PRO/100 Family of Adapters
+=============================================================
 
 June 1, 2018
 
@@ -21,7 +21,7 @@ Contents
 In This Release
 ===============
 
-This file describes the Linux* Base Driver for the Intel(R) PRO/100 Family of
+This file describes the Linux Base Driver for the Intel(R) PRO/100 Family of
 Adapters. This driver includes support for Itanium(R)2-based systems.
 
 For questions related to hardware requirements, refer to the documentation
@@ -138,9 +138,9 @@ version 1.6 or later is required for this functionality.
 The latest release of ethtool can be found from
 https://www.kernel.org/pub/software/network/ethtool/
 
-Enabling Wake on LAN* (WoL)
----------------------------
-WoL is provided through the ethtool* utility.  For instructions on
+Enabling Wake on LAN (WoL)
+--------------------------
+WoL is provided through the ethtool utility.  For instructions on
 enabling WoL with ethtool, refer to the ethtool man page.  WoL will be
 enabled on the system during the next shut down or reboot.  For this
 driver version, in order to enable WoL, the e100 driver must be loaded
diff --git a/Documentation/networking/device_drivers/intel/e1000.rst b/Documentation/networking/device_drivers/intel/e1000.rst
index 956560b6e745..4aaae0f7d6ba 100644
--- a/Documentation/networking/device_drivers/intel/e1000.rst
+++ b/Documentation/networking/device_drivers/intel/e1000.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-===========================================================
-Linux* Base Driver for Intel(R) Ethernet Network Connection
-===========================================================
+==========================================================
+Linux Base Driver for Intel(R) Ethernet Network Connection
+==========================================================
 
 Intel Gigabit Linux driver.
 Copyright(c) 1999 - 2013 Intel Corporation.
@@ -438,10 +438,10 @@ ethtool
   The latest release of ethtool can be found from
   https://www.kernel.org/pub/software/network/ethtool/
 
-Enabling Wake on LAN* (WoL)
----------------------------
+Enabling Wake on LAN (WoL)
+--------------------------
 
-  WoL is configured through the ethtool* utility.
+  WoL is configured through the ethtool utility.
 
   WoL will be enabled on the system during the next shut down or reboot.
   For this driver version, in order to enable WoL, the e1000 driver must be
diff --git a/Documentation/networking/device_drivers/intel/e1000e.rst b/Documentation/networking/device_drivers/intel/e1000e.rst
index 01999f05509c..f49cd370e7bf 100644
--- a/Documentation/networking/device_drivers/intel/e1000e.rst
+++ b/Documentation/networking/device_drivers/intel/e1000e.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-======================================================
-Linux* Driver for Intel(R) Ethernet Network Connection
-======================================================
+=====================================================
+Linux Driver for Intel(R) Ethernet Network Connection
+=====================================================
 
 Intel Gigabit Linux driver.
 Copyright(c) 2008-2018 Intel Corporation.
@@ -338,7 +338,7 @@ and higher cannot be forced. Use the autonegotiation advertising setting to
 manually set devices for 1 Gbps and higher.
 
 Speed, duplex, and autonegotiation advertising are configured through the
-ethtool* utility.
+ethtool utility.
 
 Caution: Only experienced network administrators should force speed and duplex
 or change autonegotiation advertising manually. The settings at the switch must
@@ -351,9 +351,9 @@ will not attempt to auto-negotiate with its link partner since those adapters
 operate only in full duplex and only at their native speed.
 
 
-Enabling Wake on LAN* (WoL)
----------------------------
-WoL is configured through the ethtool* utility.
+Enabling Wake on LAN (WoL)
+--------------------------
+WoL is configured through the ethtool utility.
 
 WoL will be enabled on the system during the next shut down or reboot. For
 this driver version, in order to enable WoL, the e1000e driver must be loaded
diff --git a/Documentation/networking/device_drivers/intel/fm10k.rst b/Documentation/networking/device_drivers/intel/fm10k.rst
index ac3269e34f55..4d279e64e221 100644
--- a/Documentation/networking/device_drivers/intel/fm10k.rst
+++ b/Documentation/networking/device_drivers/intel/fm10k.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-==============================================================
-Linux* Base Driver for Intel(R) Ethernet Multi-host Controller
-==============================================================
+=============================================================
+Linux Base Driver for Intel(R) Ethernet Multi-host Controller
+=============================================================
 
 August 20, 2018
 Copyright(c) 2015-2018 Intel Corporation.
@@ -120,8 +120,8 @@ rx-flow-hash tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6 m|v|t|s|d|f|n|r
 Known Issues/Troubleshooting
 ============================
 
-Enabling SR-IOV in a 64-bit Microsoft* Windows Server* 2012/R2 guest OS under Linux KVM
----------------------------------------------------------------------------------------
+Enabling SR-IOV in a 64-bit Microsoft Windows Server 2012/R2 guest OS under Linux KVM
+-------------------------------------------------------------------------------------
 KVM Hypervisor/VMM supports direct assignment of a PCIe device to a VM. This
 includes traditional PCIe devices, as well as SR-IOV-capable devices based on
 the Intel Ethernet Controller XL710.
diff --git a/Documentation/networking/device_drivers/intel/i40e.rst b/Documentation/networking/device_drivers/intel/i40e.rst
index 848fd388fa6e..8a9b18573688 100644
--- a/Documentation/networking/device_drivers/intel/i40e.rst
+++ b/Documentation/networking/device_drivers/intel/i40e.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-==================================================================
-Linux* Base Driver for the Intel(R) Ethernet Controller 700 Series
-==================================================================
+=================================================================
+Linux Base Driver for the Intel(R) Ethernet Controller 700 Series
+=================================================================
 
 Intel 40 Gigabit Linux driver.
 Copyright(c) 1999-2018 Intel Corporation.
@@ -384,7 +384,7 @@ NOTE: You cannot set the speed for devices based on the Intel(R) Ethernet
 Network Adapter XXV710 based devices.
 
 Speed, duplex, and autonegotiation advertising are configured through the
-ethtool* utility.
+ethtool utility.
 
 Caution: Only experienced network administrators should force speed and duplex
 or change autonegotiation advertising manually. The settings at the switch must
diff --git a/Documentation/networking/device_drivers/intel/iavf.rst b/Documentation/networking/device_drivers/intel/iavf.rst
index cfc08842e32c..84ac7e75f363 100644
--- a/Documentation/networking/device_drivers/intel/iavf.rst
+++ b/Documentation/networking/device_drivers/intel/iavf.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-==================================================================
-Linux* Base Driver for Intel(R) Ethernet Adaptive Virtual Function
-==================================================================
+=================================================================
+Linux Base Driver for Intel(R) Ethernet Adaptive Virtual Function
+=================================================================
 
 Intel Ethernet Adaptive Virtual Function Linux driver.
 Copyright(c) 2013-2018 Intel Corporation.
@@ -19,7 +19,7 @@ Contents
 Overview
 ========
 
-This file describes the iavf Linux* Base Driver. This driver was formerly
+This file describes the iavf Linux Base Driver. This driver was formerly
 called i40evf.
 
 The iavf driver supports the below mentioned virtual function devices and
diff --git a/Documentation/networking/device_drivers/intel/ice.rst b/Documentation/networking/device_drivers/intel/ice.rst
index c220aa2711c6..ee43ea57d443 100644
--- a/Documentation/networking/device_drivers/intel/ice.rst
+++ b/Documentation/networking/device_drivers/intel/ice.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-===================================================================
-Linux* Base Driver for the Intel(R) Ethernet Connection E800 Series
-===================================================================
+==================================================================
+Linux Base Driver for the Intel(R) Ethernet Connection E800 Series
+==================================================================
 
 Intel ice Linux driver.
 Copyright(c) 2018 Intel Corporation.
diff --git a/Documentation/networking/device_drivers/intel/igb.rst b/Documentation/networking/device_drivers/intel/igb.rst
index fc8cfaa5dcfa..87e560fe5eaa 100644
--- a/Documentation/networking/device_drivers/intel/igb.rst
+++ b/Documentation/networking/device_drivers/intel/igb.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-===========================================================
-Linux* Base Driver for Intel(R) Ethernet Network Connection
-===========================================================
+==========================================================
+Linux Base Driver for Intel(R) Ethernet Network Connection
+==========================================================
 
 Intel Gigabit Linux driver.
 Copyright(c) 1999-2018 Intel Corporation.
@@ -129,9 +129,9 @@ version is required for this functionality. Download it at:
 https://www.kernel.org/pub/software/network/ethtool/
 
 
-Enabling Wake on LAN* (WoL)
----------------------------
-WoL is configured through the ethtool* utility.
+Enabling Wake on LAN (WoL)
+--------------------------
+WoL is configured through the ethtool utility.
 
 WoL will be enabled on the system during the next shut down or reboot. For
 this driver version, in order to enable WoL, the igb driver must be loaded
diff --git a/Documentation/networking/device_drivers/intel/igbvf.rst b/Documentation/networking/device_drivers/intel/igbvf.rst
index 9cddabe8108e..557fc020ef31 100644
--- a/Documentation/networking/device_drivers/intel/igbvf.rst
+++ b/Documentation/networking/device_drivers/intel/igbvf.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-============================================================
-Linux* Base Virtual Function Driver for Intel(R) 1G Ethernet
-============================================================
+===========================================================
+Linux Base Virtual Function Driver for Intel(R) 1G Ethernet
+===========================================================
 
 Intel Gigabit Virtual Function Linux driver.
 Copyright(c) 1999-2018 Intel Corporation.
diff --git a/Documentation/networking/device_drivers/intel/ixgbe.rst b/Documentation/networking/device_drivers/intel/ixgbe.rst
index c7d25483fedb..f1d5233e5e51 100644
--- a/Documentation/networking/device_drivers/intel/ixgbe.rst
+++ b/Documentation/networking/device_drivers/intel/ixgbe.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-=============================================================================
-Linux* Base Driver for the Intel(R) Ethernet 10 Gigabit PCI Express Adapters
-=============================================================================
+===========================================================================
+Linux Base Driver for the Intel(R) Ethernet 10 Gigabit PCI Express Adapters
+===========================================================================
 
 Intel 10 Gigabit Linux driver.
 Copyright(c) 1999-2018 Intel Corporation.
@@ -519,8 +519,8 @@ The offload is also supported for ixgbe's VFs, but the VF must be set as
 Known Issues/Troubleshooting
 ============================
 
-Enabling SR-IOV in a 64-bit Microsoft* Windows Server* 2012/R2 guest OS
------------------------------------------------------------------------
+Enabling SR-IOV in a 64-bit Microsoft Windows Server 2012/R2 guest OS
+---------------------------------------------------------------------
 Linux KVM Hypervisor/VMM supports direct assignment of a PCIe device to a VM.
 This includes traditional PCIe devices, as well as SR-IOV-capable devices based
 on the Intel Ethernet Controller XL710.
diff --git a/Documentation/networking/device_drivers/intel/ixgbevf.rst b/Documentation/networking/device_drivers/intel/ixgbevf.rst
index 5d4977360157..76bbde736f21 100644
--- a/Documentation/networking/device_drivers/intel/ixgbevf.rst
+++ b/Documentation/networking/device_drivers/intel/ixgbevf.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-=============================================================
-Linux* Base Virtual Function Driver for Intel(R) 10G Ethernet
-=============================================================
+============================================================
+Linux Base Virtual Function Driver for Intel(R) 10G Ethernet
+============================================================
 
 Intel 10 Gigabit Virtual Function Linux driver.
 Copyright(c) 1999-2018 Intel Corporation.
diff --git a/Documentation/networking/device_drivers/pensando/ionic.rst b/Documentation/networking/device_drivers/pensando/ionic.rst
index 13935896bee6..c17d680cf334 100644
--- a/Documentation/networking/device_drivers/pensando/ionic.rst
+++ b/Documentation/networking/device_drivers/pensando/ionic.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-==========================================================
-Linux* Driver for the Pensando(R) Ethernet adapter family
-==========================================================
+========================================================
+Linux Driver for the Pensando(R) Ethernet adapter family
+========================================================
 
 Pensando Linux Ethernet driver.
 Copyright(c) 2019 Pensando Systems, Inc
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 49e95f438ed7..8d4ad1d1ae26 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -207,8 +207,8 @@ TCP variables:
 
 somaxconn - INTEGER
 	Limit of socket listen() backlog, known in userspace as SOMAXCONN.
-	Defaults to 128.  See also tcp_max_syn_backlog for additional tuning
-	for TCP sockets.
+	Defaults to 4096. (Was 128 before linux-5.4)
+	See also tcp_max_syn_backlog for additional tuning for TCP sockets.
 
 tcp_abort_on_overflow - BOOLEAN
 	If listening service is too slow to accept new connections,
@@ -408,11 +408,14 @@ tcp_max_orphans - INTEGER
 	up to ~64K of unswappable memory.
 
 tcp_max_syn_backlog - INTEGER
-	Maximal number of remembered connection requests, which have not
-	received an acknowledgment from connecting client.
+	Maximal number of remembered connection requests (SYN_RECV),
+	which have not received an acknowledgment from connecting client.
+	This is a per-listener limit.
 	The minimal value is 128 for low memory machines, and it will
 	increase in proportion to the memory of machine.
 	If server suffers from overload, try increasing this number.
+	Remember to also check /proc/sys/net/core/somaxconn
+	A SYN_RECV request socket consumes about 304 bytes of memory.
 
 tcp_max_tw_buckets - INTEGER
 	Maximal number of timewait sockets held by system simultaneously.
diff --git a/Documentation/networking/tls-offload.rst b/Documentation/networking/tls-offload.rst
index 0dd3f748239f..f914e81fd3a6 100644
--- a/Documentation/networking/tls-offload.rst
+++ b/Documentation/networking/tls-offload.rst
@@ -436,6 +436,10 @@ by the driver:
    encryption.
  * ``tx_tls_ooo`` - number of TX packets which were part of a TLS stream
    but did not arrive in the expected order.
+ * ``tx_tls_skip_no_sync_data`` - number of TX packets which were part of
+   a TLS stream and arrived out-of-order, but skipped the HW offload routine
+   and went to the regular transmit flow as they were retransmissions of the
+   connection handshake.
  * ``tx_tls_drop_no_sync_data`` - number of TX packets which were part of
    a TLS stream dropped, because they arrived out of order and associated
    record could not be found.
diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst
index af64c4bb4447..a8de2fbc1caa 100644
--- a/Documentation/x86/index.rst
+++ b/Documentation/x86/index.rst
@@ -27,6 +27,7 @@ x86-specific Documentation
    mds
    microcode
    resctrl_ui
+   tsx_async_abort
    usb-legacy-support
    i386/index
    x86_64/index
diff --git a/Documentation/x86/tsx_async_abort.rst b/Documentation/x86/tsx_async_abort.rst
new file mode 100644
index 000000000000..583ddc185ba2
--- /dev/null
+++ b/Documentation/x86/tsx_async_abort.rst
@@ -0,0 +1,117 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+TSX Async Abort (TAA) mitigation
+================================
+
+.. _tsx_async_abort:
+
+Overview
+--------
+
+TSX Async Abort (TAA) is a side channel attack on internal buffers in some
+Intel processors similar to Microachitectural Data Sampling (MDS).  In this
+case certain loads may speculatively pass invalid data to dependent operations
+when an asynchronous abort condition is pending in a Transactional
+Synchronization Extensions (TSX) transaction.  This includes loads with no
+fault or assist condition. Such loads may speculatively expose stale data from
+the same uarch data structures as in MDS, with same scope of exposure i.e.
+same-thread and cross-thread. This issue affects all current processors that
+support TSX.
+
+Mitigation strategy
+-------------------
+
+a) TSX disable - one of the mitigations is to disable TSX. A new MSR
+IA32_TSX_CTRL will be available in future and current processors after
+microcode update which can be used to disable TSX. In addition, it
+controls the enumeration of the TSX feature bits (RTM and HLE) in CPUID.
+
+b) Clear CPU buffers - similar to MDS, clearing the CPU buffers mitigates this
+vulnerability. More details on this approach can be found in
+:ref:`Documentation/admin-guide/hw-vuln/mds.rst <mds>`.
+
+Kernel internal mitigation modes
+--------------------------------
+
+ =============    ============================================================
+ off              Mitigation is disabled. Either the CPU is not affected or
+                  tsx_async_abort=off is supplied on the kernel command line.
+
+ tsx disabled     Mitigation is enabled. TSX feature is disabled by default at
+                  bootup on processors that support TSX control.
+
+ verw             Mitigation is enabled. CPU is affected and MD_CLEAR is
+                  advertised in CPUID.
+
+ ucode needed     Mitigation is enabled. CPU is affected and MD_CLEAR is not
+                  advertised in CPUID. That is mainly for virtualization
+                  scenarios where the host has the updated microcode but the
+                  hypervisor does not expose MD_CLEAR in CPUID. It's a best
+                  effort approach without guarantee.
+ =============    ============================================================
+
+If the CPU is affected and the "tsx_async_abort" kernel command line parameter is
+not provided then the kernel selects an appropriate mitigation depending on the
+status of RTM and MD_CLEAR CPUID bits.
+
+Below tables indicate the impact of tsx=on|off|auto cmdline options on state of
+TAA mitigation, VERW behavior and TSX feature for various combinations of
+MSR_IA32_ARCH_CAPABILITIES bits.
+
+1. "tsx=off"
+
+=========  =========  ============  ============  ==============  ===================  ======================
+MSR_IA32_ARCH_CAPABILITIES bits     Result with cmdline tsx=off
+----------------------------------  -------------------------------------------------------------------------
+TAA_NO     MDS_NO     TSX_CTRL_MSR  TSX state     VERW can clear  TAA mitigation       TAA mitigation
+                                    after bootup  CPU buffers     tsx_async_abort=off  tsx_async_abort=full
+=========  =========  ============  ============  ==============  ===================  ======================
+    0          0           0         HW default         Yes           Same as MDS           Same as MDS
+    0          0           1        Invalid case   Invalid case       Invalid case          Invalid case
+    0          1           0         HW default         No         Need ucode update     Need ucode update
+    0          1           1          Disabled          Yes           TSX disabled          TSX disabled
+    1          X           1          Disabled           X             None needed           None needed
+=========  =========  ============  ============  ==============  ===================  ======================
+
+2. "tsx=on"
+
+=========  =========  ============  ============  ==============  ===================  ======================
+MSR_IA32_ARCH_CAPABILITIES bits     Result with cmdline tsx=on
+----------------------------------  -------------------------------------------------------------------------
+TAA_NO     MDS_NO     TSX_CTRL_MSR  TSX state     VERW can clear  TAA mitigation       TAA mitigation
+                                    after bootup  CPU buffers     tsx_async_abort=off  tsx_async_abort=full
+=========  =========  ============  ============  ==============  ===================  ======================
+    0          0           0         HW default        Yes            Same as MDS          Same as MDS
+    0          0           1        Invalid case   Invalid case       Invalid case         Invalid case
+    0          1           0         HW default        No          Need ucode update     Need ucode update
+    0          1           1          Enabled          Yes               None              Same as MDS
+    1          X           1          Enabled          X              None needed          None needed
+=========  =========  ============  ============  ==============  ===================  ======================
+
+3. "tsx=auto"
+
+=========  =========  ============  ============  ==============  ===================  ======================
+MSR_IA32_ARCH_CAPABILITIES bits     Result with cmdline tsx=auto
+----------------------------------  -------------------------------------------------------------------------
+TAA_NO     MDS_NO     TSX_CTRL_MSR  TSX state     VERW can clear  TAA mitigation       TAA mitigation
+                                    after bootup  CPU buffers     tsx_async_abort=off  tsx_async_abort=full
+=========  =========  ============  ============  ==============  ===================  ======================
+    0          0           0         HW default    Yes                Same as MDS           Same as MDS
+    0          0           1        Invalid case  Invalid case        Invalid case          Invalid case
+    0          1           0         HW default    No              Need ucode update     Need ucode update
+    0          1           1          Disabled      Yes               TSX disabled          TSX disabled
+    1          X           1          Enabled       X                 None needed           None needed
+=========  =========  ============  ============  ==============  ===================  ======================
+
+In the tables, TSX_CTRL_MSR is a new bit in MSR_IA32_ARCH_CAPABILITIES that
+indicates whether MSR_IA32_TSX_CTRL is supported.
+
+There are two control bits in IA32_TSX_CTRL MSR:
+
+      Bit 0: When set it disables the Restricted Transactional Memory (RTM)
+             sub-feature of TSX (will force all transactions to abort on the
+             XBEGIN instruction).
+
+      Bit 1: When set it disables the enumeration of the RTM and HLE feature
+             (i.e. it will make CPUID(EAX=7).EBX{bit4} and
+             CPUID(EAX=7).EBX{bit11} read as 0).