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authorGravatar Sean Christopherson <seanjc@google.com> 2024-01-09 15:02:27 -0800
committerGravatar Sean Christopherson <seanjc@google.com> 2024-01-30 15:28:02 -0800
commit7bb7fce13601d2e6818be500ef3ce0b60cd59603 (patch)
treea99e68a9dc68f53c8451e7499b024de64d4ce7ba /arch/x86/kvm/vmx
parentKVM: x86/pmu: Don't ignore bits 31:30 for RDPMC index on AMD (diff)
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KVM: x86/pmu: Prioritize VMX interception over #GP on RDPMC due to bad index
Apply the pre-intercepts RDPMC validity check only to AMD, and rename all relevant functions to make it as clear as possible that the check is not a standard PMC index check. On Intel, the basic rule is that only invalid opcodes and privilege/permission/mode checks have priority over VM-Exit, i.e. RDPMC with an invalid index should VM-Exit, not #GP. While the SDM doesn't explicitly call out RDPMC, it _does_ explicitly use RDMSR of a non-existent MSR as an example where VM-Exit has priority over #GP, and RDPMC is effectively just a variation of RDMSR. Manually testing on various Intel CPUs confirms this behavior, and the inverted priority was introduced for SVM compatibility, i.e. was not an intentional change for Intel PMUs. On AMD, *all* exceptions on RDPMC have priority over VM-Exit. Check for a NULL kvm_pmu_ops.check_rdpmc_early instead of using a RET0 static call so as to provide a convenient location to document the difference between Intel and AMD, and to again try to make it as obvious as possible that the early check is a one-off thing, not a generic "is this PMC valid?" helper. Fixes: 8061252ee0d2 ("KVM: SVM: Add intercept checks for remaining twobyte instructions") Cc: Jim Mattson <jmattson@google.com> Tested-by: Dapeng Mi <dapeng1.mi@linux.intel.com> Link: https://lore.kernel.org/r/20240109230250.424295-8-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm/vmx')
-rw-r--r--arch/x86/kvm/vmx/pmu_intel.c12
1 files changed, 0 insertions, 12 deletions
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index ec4feaef3d55..1b1f888ad32b 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -55,17 +55,6 @@ static struct kvm_pmc *intel_pmc_idx_to_pmc(struct kvm_pmu *pmu, int pmc_idx)
}
}
-static bool intel_is_valid_rdpmc_ecx(struct kvm_vcpu *vcpu, unsigned int idx)
-{
- struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
- bool fixed = idx & (1u << 30);
-
- idx &= ~(3u << 30);
-
- return fixed ? idx < pmu->nr_arch_fixed_counters
- : idx < pmu->nr_arch_gp_counters;
-}
-
static struct kvm_pmc *intel_rdpmc_ecx_to_pmc(struct kvm_vcpu *vcpu,
unsigned int idx, u64 *mask)
{
@@ -718,7 +707,6 @@ struct kvm_pmu_ops intel_pmu_ops __initdata = {
.pmc_idx_to_pmc = intel_pmc_idx_to_pmc,
.rdpmc_ecx_to_pmc = intel_rdpmc_ecx_to_pmc,
.msr_idx_to_pmc = intel_msr_idx_to_pmc,
- .is_valid_rdpmc_ecx = intel_is_valid_rdpmc_ecx,
.is_valid_msr = intel_is_valid_msr,
.get_msr = intel_pmu_get_msr,
.set_msr = intel_pmu_set_msr,