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KVM: nSVM: Don't sync vmcb02 V_IRQ back to vmcb12 if KVM (L0) is intercepting VINTR

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Don't sync vmcb02 V_IRQ back to vmcb12 if KVM (L0) is intercepting
virtual interrupts in order to request an interrupt window, as KVM
has usurped vmcb02's int_ctl.  If an interrupt window opens before
the next VM-Exit, svm_clear_vintr() will restore vmcb12's int_ctl.
If no window opens, V_IRQ will be correctly preserved in vmcb12's
int_ctl (because it was never recognized while L2 was running).

Suggested-by: Sean Christopherson <seanjc@google.com>
Link: https://lkml.kernel.org/r/Y9hybI65So5X2LFg%40google.com
Signed-off-by: Santosh Shukla <Santosh.Shukla@amd.com>
Link: https://lore.kernel.org/r/20230227084016.3368-2-santosh.shukla@amd.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Santosh Shukla
2023-02-27 14:10:06 +05:30
committed by Sean Christopherson
parent d8708b80fa
commit 5faaffab5b
1 changed files with 10 additions and 11 deletions
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21
arch/x86/kvm/svm/nested.c
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@@ -416,18 +416,17 @@ void nested_sync_control_from_vmcb02(struct vcpu_svm *svm)
/* Only a few fields of int_ctl are written by the processor. */
mask = V_IRQ_MASK | V_TPR_MASK;
if (!(svm->nested.ctl.int_ctl & V_INTR_MASKING_MASK) &&
svm_is_intercept(svm, INTERCEPT_VINTR)) {
/*
* In order to request an interrupt window, L0 is usurping
* svm->vmcb->control.int_ctl and possibly setting V_IRQ
* even if it was clear in L1's VMCB. Restoring it would be
* wrong. However, in this case V_IRQ will remain true until
* interrupt_window_interception calls svm_clear_vintr and
* restores int_ctl. We can just leave it aside.
*/
/*
* Don't sync vmcb02 V_IRQ back to vmcb12 if KVM (L0) is intercepting
* virtual interrupts in order to request an interrupt window, as KVM
* has usurped vmcb02's int_ctl. If an interrupt window opens before
* the next VM-Exit, svm_clear_vintr() will restore vmcb12's int_ctl.
* If no window opens, V_IRQ will be correctly preserved in vmcb12's
* int_ctl (because it was never recognized while L2 was running).
*/
if (svm_is_intercept(svm, INTERCEPT_VINTR) &&
!test_bit(INTERCEPT_VINTR, (unsigned long *)svm->nested.ctl.intercepts))
mask &= ~V_IRQ_MASK;
}
if (nested_vgif_enabled(svm))
mask |= V_GIF_MASK;