Intercept RDTSCP to inject #UD if RDTSC is disabled in the guest.
Note, SVM does not support intercepting RDPID. Unlike VMX's
ENABLE_RDTSCP control, RDTSCP interception does not apply to RDPID. This
is a benign virtualization hole as the host kernel (incorrectly) sets
MSR_TSC_AUX if RDTSCP is supported, and KVM loads the guest's MSR_TSC_AUX
into hardware if RDTSCP is supported in the host, i.e. KVM will not leak
the host's MSR_TSC_AUX to the guest.
But, when the kernel bug is fixed, KVM will start leaking the host's
MSR_TSC_AUX if RDPID is supported in hardware, but RDTSCP isn't available
for whatever reason. This leak will be remedied in a future commit.
Fixes: 46896c73c1a4 ("KVM: svm: add support for RDTSCP")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/svm/svm.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index a7271f31df47..8f2b184270c0 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1100,7 +1100,9 @@ static u64 svm_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
return svm->vmcb->control.tsc_offset;
}
-static void svm_check_invpcid(struct vcpu_svm *svm)
+/* Evaluate instruction intercepts that depend on guest CPUID features. */
+static void svm_recalc_instruction_intercepts(struct kvm_vcpu *vcpu,
+ struct vcpu_svm *svm)
{
/*
* Intercept INVPCID if shadow paging is enabled to sync/free shadow
@@ -1113,6 +1115,13 @@ static void svm_check_invpcid(struct vcpu_svm *svm)
else
svm_clr_intercept(svm, INTERCEPT_INVPCID);
}
+
+ if (kvm_cpu_cap_has(X86_FEATURE_RDTSCP)) {
+ if (guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
+ svm_clr_intercept(svm, INTERCEPT_RDTSCP);
+ else
+ svm_set_intercept(svm, INTERCEPT_RDTSCP);
+ }
}
static void init_vmcb(struct kvm_vcpu *vcpu)
@@ -1248,7 +1257,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
svm_clr_intercept(svm, INTERCEPT_PAUSE);
}
- svm_check_invpcid(svm);
+ svm_recalc_instruction_intercepts(vcpu, svm);
/*
* If the host supports V_SPEC_CTRL then disable the interception
@@ -3084,6 +3093,7 @@ static int (*const svm_exit_handlers[])(struct kvm_vcpu *vcpu) = {
[SVM_EXIT_STGI] = stgi_interception,
[SVM_EXIT_CLGI] = clgi_interception,
[SVM_EXIT_SKINIT] = skinit_interception,
+ [SVM_EXIT_RDTSCP] = kvm_handle_invalid_op,
[SVM_EXIT_WBINVD] = kvm_emulate_wbinvd,
[SVM_EXIT_MONITOR] = kvm_emulate_monitor,
[SVM_EXIT_MWAIT] = kvm_emulate_mwait,
@@ -4007,8 +4017,7 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
svm->nrips_enabled = kvm_cpu_cap_has(X86_FEATURE_NRIPS) &&
guest_cpuid_has(vcpu, X86_FEATURE_NRIPS);
- /* Check again if INVPCID interception if required */
- svm_check_invpcid(svm);
+ svm_recalc_instruction_intercepts(vcpu, svm);
/* For sev guests, the memory encryption bit is not reserved in CR3. */
if (sev_guest(vcpu->kvm)) {
--
2.31.1.527.g47e6f16901-goog
