linux-kernel - [PATCH 2/2] KVM: X86: Fix the comments in prepare_vmcs02

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Date:   Fri, 15 Jul 2022 19:42:11 +0800
From:   Yu Zhang <yu.c.zhang@...ux.intel.com>
To:     pbonzini@...hat.com, seanjc@...gle.com, vkuznets@...hat.com,
        jmattson@...gle.com, joro@...tes.org, wanpengli@...cent.com,
        kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] KVM: X86: Fix the comments in prepare_vmcs02_rare()

Although EB.PF in vmcs02 is still set by simply "or"ing the EB of
vmcs01 and vmcs12, the explanation is obsolete. "enable_ept" being
set is not the only reason for L0 to clear its EB.PF.

Signed-off-by: Yu Zhang <yu.c.zhang@...ux.intel.com>
---
 arch/x86/kvm/vmx/nested.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 778f82015f03..634a7d218048 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2451,10 +2451,10 @@ static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 	 * is not easy (if at all possible?) to merge L0 and L1's desires, we
 	 * simply ask to exit on each and every L2 page fault. This is done by
 	 * setting MASK=MATCH=0 and (see below) EB.PF=1.
-	 * Note that below we don't need special code to set EB.PF beyond the
-	 * "or"ing of the EB of vmcs01 and vmcs12, because when enable_ept,
-	 * vmcs01's EB.PF is 0 so the "or" will take vmcs12's value, and when
-	 * !enable_ept, EB.PF is 1, so the "or" will always be 1.
+	 * Note that EB.PF is set by "or"ing of the EB of vmcs01 and vmcs12,
+	 * because when L0 has no desire to intercept #PF, vmcs01's EB.PF is 0
+	 * so the "or" will take vmcs12's value, otherwise EB.PF is 1, so the
+	 * "or" will always be 1.
 	 */
 	if (vmx_need_pf_intercept(&vmx->vcpu)) {
 		/*
-- 
2.25.1