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git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc into kvm-master
PPC KVM fix for 5.5
- Fix a bug where we try to do an ultracall on a system without an
ultravisor.
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git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into kvm-master
KVM/arm fixes for .5.5, take #1
- Fix uninitialised sysreg accessor
- Fix handling of demand-paged device mappings
- Stop spamming the console on IMPDEF sysregs
- Relax mappings of writable memslots
- Assorted cleanups
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A device mapping is normally always mapped at Stage-2, since there
is very little gain in having it faulted in.
Nonetheless, it is possible to end-up in a situation where the device
mapping has been removed from Stage-2 (userspace munmaped the VFIO
region, and the MMU notifier did its job), but present in a userspace
mapping (userpace has mapped it back at the same address). In such
a situation, the device mapping will be demand-paged as the guest
performs memory accesses.
This requires to be careful when dealing with mapping size, cache
management, and to handle potential execution of a device mapping.
Reported-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20191211165651.7889-2-maz@kernel.org
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kvm_arch_prepare_memory_region
In kvm_arch_prepare_memory_region, arm kvm regards the memory region as
writable if the flag has no KVM_MEM_READONLY, and the vm is readonly if
!VM_WRITE.
But there is common usage for setting kvm memory region as follows:
e.g. qemu side (see the PROT_NONE flag)
1. mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
memory_region_init_ram_ptr()
2. re mmap the above area with read/write authority.
Such example is used in virtio-fs qemu codes which hasn't been upstreamed
[1]. But seems we can't forbid this example.
Without this patch, it will cause an EPERM during kvm_set_memory_region()
and cause qemu boot crash.
As told by Ard, "the underlying assumption is incorrect, i.e., that the
value of vm_flags at this point in time defines how the VMA is used
during its lifetime. There may be other cases where a VMA is created
with VM_READ vm_flags that are changed to VM_READ|VM_WRITE later, and
we are currently rejecting this use case as well."
[1] https://gitlab.com/virtio-fs/qemu/blob/5a356e/hw/virtio/vhost-user-fs.c#L488
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Jia He <justin.he@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Link: https://lore.kernel.org/r/20191206020802.196108-1-justin.he@arm.com
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kvm_vgic_create()
Use wrapper function lock_all_vcpus()/unlock_all_vcpus()
in kvm_vgic_create() to remove duplicated code dealing
with locking and unlocking all vcpus in a vm.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/1575081918-11401-1-git-send-email-linmiaohe@huawei.com
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__kvm_vgic_destroy()
In kvm_vgic_dist_init() called from kvm_vgic_map_resources(), if
dist->vgic_model is invalid, dist->spis will be freed without set
dist->spis = NULL. And in vgicv2 resources clean up path,
__kvm_vgic_destroy() will be called to free allocated resources.
And dist->spis will be freed again in clean up chain because we
forget to set dist->spis = NULL in kvm_vgic_dist_init() failed
path. So double free would happen.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/1574923128-19956-1-git-send-email-linmiaohe@huawei.com
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As arg dummy is not really needed, there's no need to pass
NULL when calling cpu_init_hyp_mode(). So clean it up.
Fixes: 67f691976662 ("arm64: kvm: allows kvm cpu hotplug")
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1574320559-5662-1-git-send-email-linmiaohe@huawei.com
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The jump label out_free_1 and out_free_2 deal with
the same stuff, so git rid of one and rename the
label out_free_0a to retain the label name order.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Conflicts:
arch/x86/kvm/vmx/vmx.c
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git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm updates for Linux 5.5:
- Allow non-ISV data aborts to be reported to userspace
- Allow injection of data aborts from userspace
- Expose stolen time to guests
- GICv4 performance improvements
- vgic ITS emulation fixes
- Simplify FWB handling
- Enable halt pool counters
- Make the emulated timer PREEMPT_RT compliant
Conflicts:
include/uapi/linux/kvm.h
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Fetching an index for any vcpu in kvm->vcpus array by traversing
the entire array everytime is costly.
This patch remembers the position of each vcpu in kvm->vcpus array
by storing it in vcpus_idx under kvm_vcpu structure.
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The out_err label and var ret is unnecessary, clean them up.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add a comment explaining the rational behind having both
no_compat open and ioctl callbacks to fend off compat tasks.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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On a system without KVM_COMPAT, we prevent IOCTLs from being issued
by a compat task. Although this prevents most silly things from
happening, it can still confuse a 32bit userspace that is able
to open the kvm device (the qemu test suite seems to be pretty
mad with this behaviour).
Take a more radical approach and return a -ENODEV to the compat
task.
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Pull kvm fixes from Paolo Bonzini:
"Fix unwinding of KVM_CREATE_VM failure, VT-d posted interrupts,
DAX/ZONE_DEVICE, and module unload/reload"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved
KVM: VMX: Introduce pi_is_pir_empty() helper
KVM: VMX: Do not change PID.NDST when loading a blocked vCPU
KVM: VMX: Consider PID.PIR to determine if vCPU has pending interrupts
KVM: VMX: Fix comment to specify PID.ON instead of PIR.ON
KVM: X86: Fix initialization of MSR lists
KVM: fix placement of refcount initialization
KVM: Fix NULL-ptr deref after kvm_create_vm fails
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Explicitly exempt ZONE_DEVICE pages from kvm_is_reserved_pfn() and
instead manually handle ZONE_DEVICE on a case-by-case basis. For things
like page refcounts, KVM needs to treat ZONE_DEVICE pages like normal
pages, e.g. put pages grabbed via gup(). But for flows such as setting
A/D bits or shifting refcounts for transparent huge pages, KVM needs to
to avoid processing ZONE_DEVICE pages as the flows in question lack the
underlying machinery for proper handling of ZONE_DEVICE pages.
This fixes a hang reported by Adam Borowski[*] in dev_pagemap_cleanup()
when running a KVM guest backed with /dev/dax memory, as KVM straight up
doesn't put any references to ZONE_DEVICE pages acquired by gup().
Note, Dan Williams proposed an alternative solution of doing put_page()
on ZONE_DEVICE pages immediately after gup() in order to simplify the
auditing needed to ensure is_zone_device_page() is called if and only if
the backing device is pinned (via gup()). But that approach would break
kvm_vcpu_{un}map() as KVM requires the page to be pinned from map() 'til
unmap() when accessing guest memory, unlike KVM's secondary MMU, which
coordinates with mmu_notifier invalidations to avoid creating stale
page references, i.e. doesn't rely on pages being pinned.
[*] http://lkml.kernel.org/r/20190919115547.GA17963@angband.pl
Reported-by: Adam Borowski <kilobyte@angband.pl>
Analyzed-by: David Hildenbrand <david@redhat.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: stable@vger.kernel.org
Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Reported by syzkaller:
=============================
WARNING: suspicious RCU usage
-----------------------------
./include/linux/kvm_host.h:536 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
no locks held by repro_11/12688.
stack backtrace:
Call Trace:
dump_stack+0x7d/0xc5
lockdep_rcu_suspicious+0x123/0x170
kvm_dev_ioctl+0x9a9/0x1260 [kvm]
do_vfs_ioctl+0x1a1/0xfb0
ksys_ioctl+0x6d/0x80
__x64_sys_ioctl+0x73/0xb0
do_syscall_64+0x108/0xaa0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Commit a97b0e773e4 (kvm: call kvm_arch_destroy_vm if vm creation fails)
sets users_count to 1 before kvm_arch_init_vm(), however, if kvm_arch_init_vm()
fails, we need to decrease this count. By moving it earlier, we can push
the decrease to out_err_no_arch_destroy_vm without introducing yet another
error label.
syzkaller source: https://syzkaller.appspot.com/x/repro.c?x=15209b84e00000
Reported-by: syzbot+75475908cd0910f141ee@syzkaller.appspotmail.com
Fixes: a97b0e773e49 ("kvm: call kvm_arch_destroy_vm if vm creation fails")
Cc: Jim Mattson <jmattson@google.com>
Analyzed-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Reported by syzkaller:
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 14727 Comm: syz-executor.3 Not tainted 5.4.0-rc4+ #0
RIP: 0010:kvm_coalesced_mmio_init+0x5d/0x110 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:121
Call Trace:
kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:3446 [inline]
kvm_dev_ioctl+0x781/0x1490 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3494
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0x196/0x1150 fs/ioctl.c:696
ksys_ioctl+0x62/0x90 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:718
do_syscall_64+0xca/0x5d0 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Commit 9121923c457d ("kvm: Allocate memslots and buses before calling kvm_arch_init_vm")
moves memslots and buses allocations around, however, if kvm->srcu/irq_srcu fails
initialization, NULL will be returned instead of error code, NULL will not be intercepted
in kvm_dev_ioctl_create_vm() and be dereferenced by kvm_coalesced_mmio_init(), this patch
fixes it.
Moving the initialization is required anyway to avoid an incorrect synchronize_srcu that
was also reported by syzkaller:
wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136
__synchronize_srcu+0x197/0x250 kernel/rcu/srcutree.c:921
synchronize_srcu_expedited kernel/rcu/srcutree.c:946 [inline]
synchronize_srcu+0x239/0x3e8 kernel/rcu/srcutree.c:997
kvm_page_track_unregister_notifier+0xe7/0x130 arch/x86/kvm/page_track.c:212
kvm_mmu_uninit_vm+0x1e/0x30 arch/x86/kvm/mmu.c:5828
kvm_arch_destroy_vm+0x4a2/0x5f0 arch/x86/kvm/x86.c:9579
kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:702 [inline]
so do it.
Reported-by: syzbot+89a8060879fa0bd2db4f@syzkaller.appspotmail.com
Reported-by: syzbot+e27e7027eb2b80e44225@syzkaller.appspotmail.com
Fixes: 9121923c457d ("kvm: Allocate memslots and buses before calling kvm_arch_init_vm")
Cc: Jim Mattson <jmattson@google.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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injection
Just like we do for WFE trapping, it can be useful to turn off
WFI trapping when the physical CPU is not oversubscribed (that
is, the vcpu is the only runnable process on this CPU) *and*
that we're using direct injection of interrupts.
The conditions are reevaluated on each vcpu_load(), ensuring that
we don't switch to this mode on a busy system.
On a GICv4 system, this has the effect of reducing the generation
of doorbell interrupts to zero when the right conditions are
met, which is a huge improvement over the current situation
(where the doorbells are screaming if the CPU ever hits a
blocking WFI).
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Link: https://lore.kernel.org/r/20191107160412.30301-3-maz@kernel.org
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In order to find out whether a vcpu is likely to be the target of
VLPIs (and to further optimize the way we deal with those), let's
track the number of VLPIs a vcpu can receive.
This gets implemented with an atomic variable that gets incremented
or decremented on map, unmap and move of a VLPI.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Link: https://lore.kernel.org/r/20191107160412.30301-2-maz@kernel.org
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The timers are canceled from an preempt-notifier which is invoked with
disabled preemption which is not allowed on PREEMPT_RT.
The timer callback is short so in could be invoked in hard-IRQ context
on -RT.
Let the timer expire on hard-IRQ context even on -RT.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Julien Grall <julien.grall@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20191107095424.16647-1-bigeasy@linutronix.de
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The page table pages corresponding to broken down large pages are zapped in
FIFO order, so that the large page can potentially be recovered, if it is
not longer being used for execution. This removes the performance penalty
for walking deeper EPT page tables.
By default, one large page will last about one hour once the guest
reaches a steady state.
Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Add a function to create a kernel thread associated with a given VM. In
particular, it ensures that the worker thread inherits the priority and
cgroups of the calling thread.
Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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In kvm_create_vm(), if we've successfully called kvm_arch_init_vm(), but
then fail later in the function, we need to call kvm_arch_destroy_vm()
so that it can do any necessary cleanup (like freeing memory).
Fixes: 44a95dae1d229a ("KVM: x86: Detect and Initialize AVIC support")
Signed-off-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Junaid Shahid <junaids@google.com>
[Remove dependency on "kvm: Don't clear reference count on
kvm_create_vm() error path" which was not committed. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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It's possible that two LPIs locate in the same "byte_offset" but target
two different vcpus, where their pending status are indicated by two
different pending tables. In such a scenario, using last_byte_offset
optimization will lead KVM relying on the wrong pending table entry.
Let us use last_ptr instead, which can be treated as a byte index into
a pending table and also, can be vcpu specific.
Fixes: 280771252c1b ("KVM: arm64: vgic-v3: KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES")
Cc: stable@vger.kernel.org
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20191029071919.177-4-yuzenghui@huawei.com
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Fix various comments, including wrong function names, grammar mistakes
and specification references.
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20191029071919.177-3-yuzenghui@huawei.com
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When the VHE code was reworked, a lot of the vgic stuff was moved around,
but the GICv4 residency code did stay untouched, meaning that we come
in and out of residency on each flush/sync, which is obviously suboptimal.
To address this, let's move things around a bit:
- Residency entry (flush) moves to vcpu_load
- Residency exit (sync) moves to vcpu_put
- On blocking (entry to WFI), we "put"
- On unblocking (exit from WFI), we "load"
Because these can nest (load/block/put/load/unblock/put, for example),
we now have per-VPE tracking of the residency state.
Additionally, vgic_v4_put gains a "need doorbell" parameter, which only
gets set to true when blocking because of a WFI. This allows a finer
control of the doorbell, which now also gets disabled as soon as
it gets signaled.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20191027144234.8395-2-maz@kernel.org
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This reorganization will allow us to call kvm_arch_destroy_vm in the
event that kvm_create_vm fails after calling kvm_arch_init_vm.
Suggested-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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kvmarm-master/next
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Add a new helper, kvm_put_kvm_no_destroy(), to handle putting a borrowed
reference[*] to the VM when installing a new file descriptor fails. KVM
expects the refcount to remain valid in this case, as the in-progress
ioctl() has an explicit reference to the VM. The primary motiviation
for the helper is to document that the 'kvm' pointer is still valid
after putting the borrowed reference, e.g. to document that doing
mutex(&kvm->lock) immediately after putting a ref to kvm isn't broken.
[*] When exposing a new object to userspace via a file descriptor, e.g.
a new vcpu, KVM grabs a reference to itself (the VM) prior to making
the object visible to userspace to avoid prematurely freeing the VM
in the scenario where userspace immediately closes file descriptor.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm fixes for 5.4, take #2
Special PMU edition:
- Fix cycle counter truncation
- Fix cycle counter overflow limit on pure 64bit system
- Allow chained events to be actually functional
- Correct sample period after overflow
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Don't waste cycles to shrink/grow vCPU halt_poll_ns if host
side polling is disabled.
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Allow user space to inform the KVM host where in the physical memory
map the paravirtualized time structures should be located.
User space can set an attribute on the VCPU providing the IPA base
address of the stolen time structure for that VCPU. This must be
repeated for every VCPU in the VM.
The address is given in terms of the physical address visible to
the guest and must be 64 byte aligned. The guest will discover the
address via a hypercall.
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Currently a kvm_device_ops structure cannot be const without triggering
compiler warnings. However the structure doesn't need to be written to
and, by marking it const, it can be read-only in memory. Add some more
const keywords to allow this.
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Implement the service call for configuring a shared structure between a
VCPU and the hypervisor in which the hypervisor can write the time
stolen from the VCPU's execution time by other tasks on the host.
User space allocates memory which is placed at an IPA also chosen by user
space. The hypervisor then updates the shared structure using
kvm_put_guest() to ensure single copy atomicity of the 64-bit value
reporting the stolen time in nanoseconds.
Whenever stolen time is enabled by the guest, the stolen time counter is
reset.
The stolen time itself is retrieved from the sched_info structure
maintained by the Linux scheduler code. We enable SCHEDSTATS when
selecting KVM Kconfig to ensure this value is meaningful.
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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This provides a mechanism for querying which paravirtualized time
features are available in this hypervisor.
Also add the header file which defines the ABI for the paravirtualized
time features we're about to add.
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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We currently intertwine the KVM PSCI implementation with the general
dispatch of hypercall handling, which makes perfect sense because PSCI
is the only category of hypercalls we support.
However, as we are about to support additional hypercalls, factor out
this functionality into a separate hypercall handler file.
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
[steven.price@arm.com: rebased]
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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In some scenarios, such as buggy guest or incorrect configuration of the
VMM and firmware description data, userspace will detect a memory access
to a portion of the IPA, which is not mapped to any MMIO region.
For this purpose, the appropriate action is to inject an external abort
to the guest. The kernel already has functionality to inject an
external abort, but we need to wire up a signal from user space that
lets user space tell the kernel to do this.
It turns out, we already have the set event functionality which we can
perfectly reuse for this.
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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For a long time, if a guest accessed memory outside of a memslot using
any of the load/store instructions in the architecture which doesn't
supply decoding information in the ESR_EL2 (the ISV bit is not set), the
kernel would print the following message and terminate the VM as a
result of returning -ENOSYS to userspace:
load/store instruction decoding not implemented
The reason behind this message is that KVM assumes that all accesses
outside a memslot is an MMIO access which should be handled by
userspace, and we originally expected to eventually implement some sort
of decoding of load/store instructions where the ISV bit was not set.
However, it turns out that many of the instructions which don't provide
decoding information on abort are not safe to use for MMIO accesses, and
the remaining few that would potentially make sense to use on MMIO
accesses, such as those with register writeback, are not used in
practice. It also turns out that fetching an instruction from guest
memory can be a pretty horrible affair, involving stopping all CPUs on
SMP systems, handling multiple corner cases of address translation in
software, and more. It doesn't appear likely that we'll ever implement
this in the kernel.
What is much more common is that a user has misconfigured his/her guest
and is actually not accessing an MMIO region, but just hitting some
random hole in the IPA space. In this scenario, the error message above
is almost misleading and has led to a great deal of confusion over the
years.
It is, nevertheless, ABI to userspace, and we therefore need to
introduce a new capability that userspace explicitly enables to change
behavior.
This patch introduces KVM_CAP_ARM_NISV_TO_USER (NISV meaning Non-ISV)
which does exactly that, and introduces a new exit reason to report the
event to userspace. User space can then emulate an exception to the
guest, restart the guest, suspend the guest, or take any other
appropriate action as per the policy of the running system.
Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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The PMU emulation code uses the perf event sample period to trigger
the overflow detection. This works fine for the *first* overflow
handling, but results in a huge number of interrupts on the host,
unrelated to the number of interrupts handled in the guest (a x20
factor is pretty common for the cycle counter). On a slow system
(such as a SW model), this can result in the guest only making
forward progress at a glacial pace.
It turns out that the clue is in the name. The sample period is
exactly that: a period. And once the an overflow has occured,
the following period should be the full width of the associated
counter, instead of whatever the guest had initially programed.
Reset the sample period to the architected value in the overflow
handler, which now results in a number of host interrupts that is
much closer to the number of interrupts in the guest.
Fixes: b02386eb7dac ("arm64: KVM: Add PMU overflow interrupt routing")
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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The current convention for KVM to request a chained event from the
host PMU is to set bit[0] in attr.config1 (PERF_ATTR_CFG1_KVM_PMU_CHAINED).
But as it turns out, this bit gets set *after* we create the kernel
event that backs our virtual counter, meaning that we never get
a 64bit counter.
Moving the setting to an earlier point solves the problem.
Fixes: 80f393a23be6 ("KVM: arm/arm64: Support chained PMU counters")
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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When a counter is disabled, its value is sampled before the event
is being disabled, and the value written back in the shadow register.
In that process, the value gets truncated to 32bit, which is adequate
for any counter but the cycle counter (defined as a 64bit counter).
This obviously results in a corrupted counter, and things like
"perf record -e cycles" not working at all when run in a guest...
A similar, but less critical bug exists in kvm_pmu_get_counter_value.
Make the truncation conditional on the counter not being the cycle
counter, which results in a minor code reorganisation.
Fixes: 80f393a23be6 ("KVM: arm/arm64: Support chained PMU counters")
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Reported-by: Julien Thierry <julien.thierry.kdev@gmail.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm fixes for 5.4, take #1
- Remove the now obsolete hyp_alternate_select construct
- Fix the TRACE_INCLUDE_PATH macro in the vgic code
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The largepages debugfs entry is incremented/decremented as shadow
pages are created or destroyed. Clearing it will result in an
underflow, which is harmless to KVM but ugly (and could be
misinterpreted by tools that use debugfs information), so make
this particular statistic read-only.
Cc: kvm-ppc@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Pull KVM updates from Paolo Bonzini:
"s390:
- ioctl hardening
- selftests
ARM:
- ITS translation cache
- support for 512 vCPUs
- various cleanups and bugfixes
PPC:
- various minor fixes and preparation
x86:
- bugfixes all over the place (posted interrupts, SVM, emulation
corner cases, blocked INIT)
- some IPI optimizations"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (75 commits)
KVM: X86: Use IPI shorthands in kvm guest when support
KVM: x86: Fix INIT signal handling in various CPU states
KVM: VMX: Introduce exit reason for receiving INIT signal on guest-mode
KVM: VMX: Stop the preemption timer during vCPU reset
KVM: LAPIC: Micro optimize IPI latency
kvm: Nested KVM MMUs need PAE root too
KVM: x86: set ctxt->have_exception in x86_decode_insn()
KVM: x86: always stop emulation on page fault
KVM: nVMX: trace nested VM-Enter failures detected by H/W
KVM: nVMX: add tracepoint for failed nested VM-Enter
x86: KVM: svm: Fix a check in nested_svm_vmrun()
KVM: x86: Return to userspace with internal error on unexpected exit reason
KVM: x86: Add kvm_emulate_{rd,wr}msr() to consolidate VXM/SVM code
KVM: x86: Refactor up kvm_{g,s}et_msr() to simplify callers
doc: kvm: Fix return description of KVM_SET_MSRS
KVM: X86: Tune PLE Window tracepoint
KVM: VMX: Change ple_window type to unsigned int
KVM: X86: Remove tailing newline for tracepoints
KVM: X86: Trace vcpu_id for vmexit
KVM: x86: Manually calculate reserved bits when loading PDPTRS
...
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The first/last indexes are typically shared with a user app.
The app can change the 'last' index that the kernel uses
to store the next result. This change sanity checks the index
before using it for writing to a potentially arbitrary address.
This fixes CVE-2019-14821.
Cc: stable@vger.kernel.org
Fixes: 5f94c1741bdc ("KVM: Add coalesced MMIO support (common part)")
Signed-off-by: Matt Delco <delco@chromium.org>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reported-by: syzbot+983c866c3dd6efa3662a@syzkaller.appspotmail.com
[Use READ_ONCE. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Commit 49dfe94fe5ad ("KVM: arm/arm64: Fix TRACE_INCLUDE_PATH") fixes
TRACE_INCLUDE_PATH to the correct relative path to the define_trace.h
and explains why did the old one work.
The same fix should be applied to virt/kvm/arm/vgic/trace.h.
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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While parts of the VGIC support a large number of vcpus (we
bravely allow up to 512), other parts are more limited.
One of these limits is visible in the KVM_IRQ_LINE ioctl, which
only allows 256 vcpus to be signalled when using the CPU or PPI
types. Unfortunately, we've cornered ourselves badly by allocating
all the bits in the irq field.
Since the irq_type subfield (8 bit wide) is currently only taking
the values 0, 1 and 2 (and we have been careful not to allow anything
else), let's reduce this field to only 4 bits, and allocate the
remaining 4 bits to a vcpu2_index, which acts as a multiplier:
vcpu_id = 256 * vcpu2_index + vcpu_index
With that, and a new capability (KVM_CAP_ARM_IRQ_LINE_LAYOUT_2)
allowing this to be discovered, it becomes possible to inject
PPIs to up to 4096 vcpus. But please just don't.
Whilst we're there, add a clarification about the use of KVM_IRQ_LINE
on arm, which is not completely conditionned by KVM_CAP_IRQCHIP.
Reported-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Will Deacon:
"Hot on the heels of our last set of fixes are a few more for -rc7.
Two of them are fixing issues with our virtual interrupt controller
implementation in KVM/arm, while the other is a longstanding but
straightforward kallsyms fix which was been acked by Masami and
resolves an initialisation failure in kprobes observed on arm64.
- Fix GICv2 emulation bug (KVM)
- Fix deadlock in virtual GIC interrupt injection code (KVM)
- Fix kprobes blacklist init failure due to broken kallsyms lookup"
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
KVM: arm/arm64: vgic-v2: Handle SGI bits in GICD_I{S,C}PENDR0 as WI
KVM: arm/arm64: vgic: Fix potential deadlock when ap_list is long
kallsyms: Don't let kallsyms_lookup_size_offset() fail on retrieving the first symbol
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