linux-kernel - [PATCH v2 02/11] KVM: nSVM: clean up the copying of V

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Message-Id: <20221129193717.513824-3-mlevitsk@redhat.com>
Date:   Tue, 29 Nov 2022 21:37:08 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Sandipan Das <sandipan.das@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
        Jiaxi Chen <jiaxi.chen@...ux.intel.com>,
        Babu Moger <babu.moger@....com>, linux-kernel@...r.kernel.org,
        Jing Liu <jing2.liu@...el.com>,
        Wyes Karny <wyes.karny@....com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v2 02/11] KVM: nSVM: clean up the copying of V_INTR bits from vmcb02 to vmcb12

the V_IRQ and v_TPR bits don't exist when virtual interrupt
masking is not enabled, therefore the KVM should not copy these
bits regardless of V_IRQ intercept.

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/svm/nested.c | 23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 37af0338da7c32..aad3145b2f62fe 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -412,24 +412,17 @@ void nested_copy_vmcb_save_to_cache(struct vcpu_svm *svm,
  */
 void nested_sync_control_from_vmcb02(struct vcpu_svm *svm)
 {
-	u32 mask;
+	u32 mask = 0;
 	svm->nested.ctl.event_inj      = svm->vmcb->control.event_inj;
 	svm->nested.ctl.event_inj_err  = svm->vmcb->control.event_inj_err;
 
-	/* 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.
-		 */
-		mask &= ~V_IRQ_MASK;
-	}
+	/*
+	 * Only a few fields of int_ctl are written by the processor.
+	 * Copy back only the bits that are passed through to the L2.
+	 */
+
+	if (svm->nested.ctl.int_ctl & V_INTR_MASKING_MASK)
+		mask = V_IRQ_MASK | V_TPR_MASK;
 
 	if (nested_vgif_enabled(svm))
 		mask |= V_GIF_MASK;
-- 
2.26.3