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KVM: SVM: Recalc instructions intercepts when EFER.SVME is toggled

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The AMD APM states that VMRUN, VMLOAD, VMSAVE, CLGI, VMMCALL, and
INVLPGA instructions should generate a #UD when EFER.SVME is cleared.
Currently, when VMLOAD, VMSAVE, or CLGI are executed in L1 with
EFER.SVME cleared, no #UD is generated in certain cases. This is because
the intercepts for these instructions are cleared based on whether or
not vls or vgif is enabled. The #UD fails to be generated when the
intercepts are absent.

Fix the missing #UD generation by ensuring that all relevant
instructions have intercepts set when SVME.EFER is disabled.

VMMCALL is special because KVM's ABI is that VMCALL/VMMCALL are always
supported for L1 and never fault.

Signed-off-by: Kevin Cheng <chengkev@google.com>
[sean: isolate Intel CPU "compatibility" in EFER.SVME=1 path]
Reviewed-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260304003010.1108257-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Kevin Cheng 2026-03-03 16:30:10 -08:00 committed by Sean Christopherson
parent 69f779f79e
commit 460c7eb2e7
1 changed files with 23 additions and 12 deletions
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35
arch/x86/kvm/svm/svm.c
View File

@ -245,6 +245,8 @@ int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
if (svm_gp_erratum_intercept && !sev_guest(vcpu->kvm))
set_exception_intercept(svm, GP_VECTOR);
}
kvm_make_request(KVM_REQ_RECALC_INTERCEPTS, vcpu);
}
svm->vmcb->save.efer = efer | EFER_SVME;
@ -1032,27 +1034,31 @@ static void svm_recalc_instruction_intercepts(struct kvm_vcpu *vcpu)
}
/*
* No need to toggle VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK here, it is
* always set if vls is enabled. If the intercepts are set, the bit is
* meaningless anyway.
* Intercept instructions that #UD if EFER.SVME=0, as SVME must be set
* even when running the guest, i.e. hardware will only ever see
* EFER.SVME=1.
*
* No need to toggle any of the vgif/vls/etc. enable bits here, as they
* are set when the VMCB is initialized and never cleared (if the
* relevant intercepts are set, the enablements are meaningless anyway).
*/
if (guest_cpuid_is_intel_compatible(vcpu)) {
if (!(vcpu->arch.efer & EFER_SVME)) {
svm_set_intercept(svm, INTERCEPT_VMLOAD);
svm_set_intercept(svm, INTERCEPT_VMSAVE);
svm_set_intercept(svm, INTERCEPT_CLGI);
svm_set_intercept(svm, INTERCEPT_STGI);
} else {
/*
* If hardware supports Virtual VMLOAD VMSAVE then enable it
* in VMCB and clear intercepts to avoid #VMEXIT.
*/
if (vls) {
if (guest_cpuid_is_intel_compatible(vcpu)) {
svm_set_intercept(svm, INTERCEPT_VMLOAD);
svm_set_intercept(svm, INTERCEPT_VMSAVE);
} else if (vls) {
svm_clr_intercept(svm, INTERCEPT_VMLOAD);
svm_clr_intercept(svm, INTERCEPT_VMSAVE);
}
}
if (vgif) {
svm_clr_intercept(svm, INTERCEPT_STGI);
svm_clr_intercept(svm, INTERCEPT_CLGI);
/*
* Process pending events when clearing STGI/CLGI intercepts if
@ -1060,8 +1066,13 @@ static void svm_recalc_instruction_intercepts(struct kvm_vcpu *vcpu)
* that KVM re-evaluates if the intercept needs to be set again
* to track when GIF is re-enabled (e.g. for NMI injection).
*/
if (svm_has_pending_gif_event(svm))
kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
if (vgif) {
svm_clr_intercept(svm, INTERCEPT_CLGI);
svm_clr_intercept(svm, INTERCEPT_STGI);
if (svm_has_pending_gif_event(svm))
kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
}
}
if (kvm_need_rdpmc_intercept(vcpu))