Merge branch 'sev-v9-p2' of https://github.com/codomania/kvm

This part of Secure Encrypted Virtualization (SEV) patch series focuses on KVM
changes required to create and manage SEV guests.

SEV is an extension to the AMD-V architecture which supports running encrypted
virtual machine (VMs) under the control of a hypervisor. Encrypted VMs have their
pages (code and data) secured such that only the guest itself has access to
unencrypted version. Each encrypted VM is associated with a unique encryption key;
if its data is accessed to a different entity using a different key the encrypted
guest's data will be incorrectly decrypted, leading to unintelligible data.
This security model ensures that hypervisor will no longer able to inspect or
alter any guest code or data.

The key management of this feature is handled by a separate processor known as
the AMD Secure Processor (AMD-SP) which is present on AMD SOCs. The SEV Key
Management Specification (see below) provides a set of commands which can be
used by hypervisor to load virtual machine keys through the AMD-SP driver.

The patch series adds a new ioctl in KVM driver (KVM_MEMORY_ENCRYPT_OP). The
ioctl will be used by qemu to issue SEV guest-specific commands defined in Key
Management Specification.

The following links provide additional details:

AMD Memory Encryption white paper:
http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2013/12/AMD_Memory_Encryption_Whitepaper_v7-Public.pdf

AMD64 Architecture Programmer's Manual:
    http://support.amd.com/TechDocs/24593.pdf
    SME is section 7.10
    SEV is section 15.34

SEV Key Management:
http://support.amd.com/TechDocs/55766_SEV-KM API_Specification.pdf

KVM Forum Presentation:
http://www.linux-kvm.org/images/7/74/02x08A-Thomas_Lendacky-AMDs_Virtualizatoin_Memory_Encryption_Technology.pdf

SEV Guest BIOS support:
  SEV support has been add to EDKII/OVMF BIOS
  https://github.com/tianocore/edk2

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 46 insertions, 20 deletions

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index bcb75dc97d44..df8a2418aadf 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -556,6 +556,51 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 	}
 }
 
+static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
+{
+	u64 msr;
+
+	/*
+	 * BIOS support is required for SME and SEV.
+	 *   For SME: If BIOS has enabled SME then adjust x86_phys_bits by
+	 *	      the SME physical address space reduction value.
+	 *	      If BIOS has not enabled SME then don't advertise the
+	 *	      SME feature (set in scattered.c).
+	 *   For SEV: If BIOS has not enabled SEV then don't advertise the
+	 *            SEV feature (set in scattered.c).
+	 *
+	 *   In all cases, since support for SME and SEV requires long mode,
+	 *   don't advertise the feature under CONFIG_X86_32.
+	 */
+	if (cpu_has(c, X86_FEATURE_SME) || cpu_has(c, X86_FEATURE_SEV)) {
+		/* Check if memory encryption is enabled */
+		rdmsrl(MSR_K8_SYSCFG, msr);
+		if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
+			goto clear_all;
+
+		/*
+		 * Always adjust physical address bits. Even though this
+		 * will be a value above 32-bits this is still done for
+		 * CONFIG_X86_32 so that accurate values are reported.
+		 */
+		c->x86_phys_bits -= (cpuid_ebx(0x8000001f) >> 6) & 0x3f;
+
+		if (IS_ENABLED(CONFIG_X86_32))
+			goto clear_all;
+
+		rdmsrl(MSR_K7_HWCR, msr);
+		if (!(msr & MSR_K7_HWCR_SMMLOCK))
+			goto clear_sev;
+
+		return;
+
+clear_all:
+		clear_cpu_cap(c, X86_FEATURE_SME);
+clear_sev:
+		clear_cpu_cap(c, X86_FEATURE_SEV);
+	}
+}
+
 static void early_init_amd(struct cpuinfo_x86 *c)
 {
 	u32 dummy;
@@ -627,26 +672,7 @@ static void early_init_amd(struct cpuinfo_x86 *c)
 	if (cpu_has_amd_erratum(c, amd_erratum_400))
 		set_cpu_bug(c, X86_BUG_AMD_E400);
 
-	/*
-	 * BIOS support is required for SME. If BIOS has enabled SME then
-	 * adjust x86_phys_bits by the SME physical address space reduction
-	 * value. If BIOS has not enabled SME then don't advertise the
-	 * feature (set in scattered.c). Also, since the SME support requires
-	 * long mode, don't advertise the feature under CONFIG_X86_32.
-	 */
-	if (cpu_has(c, X86_FEATURE_SME)) {
-		u64 msr;
-
-		/* Check if SME is enabled */
-		rdmsrl(MSR_K8_SYSCFG, msr);
-		if (msr & MSR_K8_SYSCFG_MEM_ENCRYPT) {
-			c->x86_phys_bits -= (cpuid_ebx(0x8000001f) >> 6) & 0x3f;
-			if (IS_ENABLED(CONFIG_X86_32))
-				clear_cpu_cap(c, X86_FEATURE_SME);
-		} else {
-			clear_cpu_cap(c, X86_FEATURE_SME);
-		}
-	}
+	early_detect_mem_encrypt(c);
 }
 
 static void init_amd_k8(struct cpuinfo_x86 *c)