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authorLiran Alon <liran.alon@oracle.com>2019-03-25 21:09:17 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2019-04-16 15:37:34 +0200
commite51bfdb68725dc052d16241ace40ea3140f938aa (patch)
tree3413e07454f91e271d62cc6a71af4fe9ffc6f577 /arch/x86/kvm
parent672ff6cff80ca43bf3258410d2b887036969df5f (diff)
KVM: nVMX: Expose RDPMC-exiting only when guest supports PMU
Issue was discovered when running kvm-unit-tests on KVM running as L1 on top of Hyper-V. When vmx_instruction_intercept unit-test attempts to run RDPMC to test RDPMC-exiting, it is intercepted by L1 KVM which it's EXIT_REASON_RDPMC handler raise #GP because vCPU exposed by Hyper-V doesn't support PMU. Instead of unit-test expectation to be reflected with EXIT_REASON_RDPMC. The reason vmx_instruction_intercept unit-test attempts to run RDPMC even though Hyper-V doesn't support PMU is because L1 expose to L2 support for RDPMC-exiting. Which is reasonable to assume that is supported only in case CPU supports PMU to being with. Above issue can easily be simulated by modifying vmx_instruction_intercept config in x86/unittests.cfg to run QEMU with "-cpu host,+vmx,-pmu" and run unit-test. To handle issue, change KVM to expose RDPMC-exiting only when guest supports PMU. Reported-by: Saar Amar <saaramar@microsoft.com> Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com> Reviewed-by: Jim Mattson <jmattson@google.com> Signed-off-by: Liran Alon <liran.alon@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/vmx/vmx.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 88060a621db2..5866e9e9f1e0 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6856,6 +6856,30 @@ static void nested_vmx_entry_exit_ctls_update(struct kvm_vcpu *vcpu)
}
}
+static bool guest_cpuid_has_pmu(struct kvm_vcpu *vcpu)
+{
+ struct kvm_cpuid_entry2 *entry;
+ union cpuid10_eax eax;
+
+ entry = kvm_find_cpuid_entry(vcpu, 0xa, 0);
+ if (!entry)
+ return false;
+
+ eax.full = entry->eax;
+ return (eax.split.version_id > 0);
+}
+
+static void nested_vmx_procbased_ctls_update(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ bool pmu_enabled = guest_cpuid_has_pmu(vcpu);
+
+ if (pmu_enabled)
+ vmx->nested.msrs.procbased_ctls_high |= CPU_BASED_RDPMC_EXITING;
+ else
+ vmx->nested.msrs.procbased_ctls_high &= ~CPU_BASED_RDPMC_EXITING;
+}
+
static void update_intel_pt_cfg(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -6944,6 +6968,7 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
if (nested_vmx_allowed(vcpu)) {
nested_vmx_cr_fixed1_bits_update(vcpu);
nested_vmx_entry_exit_ctls_update(vcpu);
+ nested_vmx_procbased_ctls_update(vcpu);
}
if (boot_cpu_has(X86_FEATURE_INTEL_PT) &&