linux-kernel - [PATCH 16/28] KVM: nSVM: restore clobbered INT

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Message-Id: <20200526172308.111575-17-pbonzini@redhat.com>
Date:   Tue, 26 May 2020 13:22:56 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     vkuznets@...hat.com, mlevitsk@...hat.com,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jim Mattson <jmattson@...gle.com>
Subject: [PATCH 16/28] KVM: nSVM: restore clobbered INT_CTL fields after clearing VINTR

Restore the INT_CTL value from the guest's VMCB once we've stopped using
it, so that virtual interrupts can be injected as requested by L1.
V_TPR is up-to-date however, and it can change if the guest writes to CR8,
so keep it.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/svm/svm.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 77d3f441cd87..c213011a82e3 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1365,9 +1365,17 @@ static void svm_set_vintr(struct vcpu_svm *svm)
 
 static void svm_clear_vintr(struct vcpu_svm *svm)
 {
+	const u32 mask = V_TPR_MASK | V_GIF_ENABLE_MASK | V_GIF_MASK | V_INTR_MASKING_MASK;
 	clr_intercept(svm, INTERCEPT_VINTR);
 
-	svm->vmcb->control.int_ctl &= ~V_IRQ_MASK;
+	/* Drop int_ctl fields related to VINTR injection.  */
+	svm->vmcb->control.int_ctl &= mask;
+	if (is_guest_mode(&svm->vcpu)) {
+		WARN_ON((svm->vmcb->control.int_ctl & V_TPR_MASK) !=
+			(svm->nested.ctl.int_ctl & V_TPR_MASK));
+		svm->vmcb->control.int_ctl |= svm->nested.ctl.int_ctl & ~mask;
+	}
+
 	mark_dirty(svm->vmcb, VMCB_INTR);
 }
 
-- 
2.26.2