linux-kernel - [PATCH 05/10] KVM: x86: nSVM: Cache g_pat in vmcb_save_area

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Message-ID: <20260113003016.3511895-6-jmattson@google.com>
Date: Mon, 12 Jan 2026 16:30:00 -0800
From: Jim Mattson <jmattson@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	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>, Shuah Khan <shuah@...nel.org>, Joerg Roedel <joro@...tes.org>, 
	Avi Kivity <avi@...hat.com>, Alexander Graf <agraf@...e.de>, 
	"Radim Krčmář" <rkrcmar@...hat.com>, David Hildenbrand <david@...nel.org>, Cathy Avery <cavery@...hat.com>, 
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-kselftest@...r.kernel.org
Cc: Jim Mattson <jmattson@...gle.com>
Subject: [PATCH 05/10] KVM: x86: nSVM: Cache g_pat in vmcb_save_area_cached

The g_pat field from the vmcb12 save state area must be validated. To
accommodate validation without TOCTTOU issues, add a g_pat field to
the vmcb_save_area_cached struct, and include it in the fields copied
by __nested_copy_vmcb_save_to_cache().

Fixes: 3d6368ef580a ("KVM: SVM: Add VMRUN handler")
Signed-off-by: Jim Mattson <jmattson@...gle.com>
---
 arch/x86/kvm/svm/nested.c | 2 ++
 arch/x86/kvm/svm/svm.h    | 1 +
 2 files changed, 3 insertions(+)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 9aec836ac04c..ad9272aae908 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -506,6 +506,8 @@ static void __nested_copy_vmcb_save_to_cache(struct vmcb_save_area_cached *to,
 
 	to->dr6 = from->dr6;
 	to->dr7 = from->dr7;
+
+	to->g_pat = from->g_pat;
 }
 
 void nested_copy_vmcb_save_to_cache(struct vcpu_svm *svm,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 7d28a739865f..39138378531e 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -145,6 +145,7 @@ struct vmcb_save_area_cached {
 	u64 cr0;
 	u64 dr7;
 	u64 dr6;
+	u64 g_pat;
 };
 
 struct vmcb_ctrl_area_cached {
-- 
2.52.0.457.g6b5491de43-goog