linux-kernel - [PATCH 3/3] KVM: VMX: Mark VCPU_EXREG_CR3 dirty when !CR0_PG -> CR0

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Message-Id: <20211216021938.11752-4-jiangshanlai@gmail.com>
Date:   Thu, 16 Dec 2021 10:19:38 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Cc:     Lai Jiangshan <laijs@...ux.alibaba.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH 3/3] KVM: VMX: Mark VCPU_EXREG_CR3 dirty when !CR0_PG -> CR0_PG if EPT + !URG

From: Lai Jiangshan <laijs@...ux.alibaba.com>

When !CR0_PG -> CR0_PG, vcpu->arch.cr3 becomes active, but GUEST_CR3 is
still vmx->ept_identity_map_addr if EPT + !URG.  So VCPU_EXREG_CR3 is
considered to be dirty and GUEST_CR3 needs to be updated in this case.

Reported-by: Maxim Levitsky <mlevitsk@...hat.com>
Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 arch/x86/kvm/vmx/vmx.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 5f281f5ee961..e2d535fe0387 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3066,6 +3066,13 @@ void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
 		/* Note, vmx_set_cr4() consumes the new vcpu->arch.cr0. */
 		if ((old_cr0_pg ^ cr0) & X86_CR0_PG)
 			vmx_set_cr4(vcpu, kvm_read_cr4(vcpu));
+
+		/*
+		 * When !CR0_PG -> CR0_PG, vcpu->arch.cr3 becomes active, but
+		 * GUEST_CR3 is still vmx->ept_identity_map_addr if EPT + !URG.
+		 */
+		if (!(old_cr0_pg & X86_CR0_PG) && (cr0 & X86_CR0_PG))
+			kvm_register_mark_dirty(vcpu, VCPU_EXREG_CR3);
 	}
 
 	/* depends on vcpu->arch.cr0 to be set to a new value */
-- 
2.19.1.6.gb485710b