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| author | Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> | 2024-11-04 08:58:45 +0100 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-12-20 02:47:51 +0100 |
| commit | d81cadbe164265337f149cf31c9462d7217c1eed (patch) | |
| tree | 8cca796f9e3f45ba61973d5ea2a947eddaab5755 /arch/x86 | |
| parent | Merge tag 'vfs-6.13-rc1.fixes' of git://git.kernel.org/pub/scm/linux/kernel/g... (diff) | |
| download | linux-d81cadbe164265337f149cf31c9462d7217c1eed.tar.xz linux-d81cadbe164265337f149cf31c9462d7217c1eed.zip | |
KVM: SVM: Disable AVIC on SNP-enabled system without HvInUseWrAllowed feature
On SNP-enabled system, VMRUN marks AVIC Backing Page as in-use while
the guest is running for both secure and non-secure guest. Any hypervisor
write to the in-use vCPU's AVIC backing page (e.g. to inject an interrupt)
will generate unexpected #PF in the host.
Currently, attempt to run AVIC guest would result in the following error:
BUG: unable to handle page fault for address: ff3a442e549cc270
#PF: supervisor write access in kernel mode
#PF: error_code(0x80000003) - RMP violation
PGD b6ee01067 P4D b6ee02067 PUD 10096d063 PMD 11c540063 PTE 80000001149cc163
SEV-SNP: PFN 0x1149cc unassigned, dumping non-zero entries in 2M PFN region: [0x114800 - 0x114a00]
...
Newer AMD system is enhanced to allow hypervisor to modify the backing page
for non-secure guest on SNP-enabled system. This enhancement is available
when the CPUID Fn8000_001F_EAX bit 30 is set (HvInUseWrAllowed).
This table describes AVIC support matrix w.r.t. SNP enablement:
| Non-SNP system | SNP system
-----------------------------------------------------
Non-SNP guest | AVIC Activate | AVIC Activate iff
| | HvInuseWrAllowed=1
-----------------------------------------------------
SNP guest | N/A | Secure AVIC
Therefore, check and disable AVIC in kvm_amd driver when the feature is not
available on SNP-enabled system.
See the AMD64 Architecture Programmer’s Manual (APM) Volume 2 for detail.
(https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/
programmer-references/40332.pdf)
Fixes: 216d106c7ff7 ("x86/sev: Add SEV-SNP host initialization support")
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Link: https://lore.kernel.org/r/20241104075845.7583-1-suravee.suthikulpanit@amd.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/cpufeatures.h | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/svm/avic.c | 6 |
2 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 17b6590748c0..645aa360628d 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -452,6 +452,7 @@ #define X86_FEATURE_SME_COHERENT (19*32+10) /* AMD hardware-enforced cache coherency */ #define X86_FEATURE_DEBUG_SWAP (19*32+14) /* "debug_swap" AMD SEV-ES full debug state swap support */ #define X86_FEATURE_SVSM (19*32+28) /* "svsm" SVSM present */ +#define X86_FEATURE_HV_INUSE_WR_ALLOWED (19*32+30) /* Allow Write to in-use hypervisor-owned pages */ /* AMD-defined Extended Feature 2 EAX, CPUID level 0x80000021 (EAX), word 20 */ #define X86_FEATURE_NO_NESTED_DATA_BP (20*32+ 0) /* No Nested Data Breakpoints */ diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index 4b74ea91f4e6..65fd245a9953 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -1199,6 +1199,12 @@ bool avic_hardware_setup(void) return false; } + if (cc_platform_has(CC_ATTR_HOST_SEV_SNP) && + !boot_cpu_has(X86_FEATURE_HV_INUSE_WR_ALLOWED)) { + pr_warn("AVIC disabled: missing HvInUseWrAllowed on SNP-enabled system\n"); + return false; + } + if (boot_cpu_has(X86_FEATURE_AVIC)) { pr_info("AVIC enabled\n"); } else if (force_avic) { |