From nobody Sun Apr 5 21:16:10 2026 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A421A23C503 for ; Tue, 24 Feb 2026 00:55:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771894515; cv=none; b=hV07UYcX65yf4fMBzlrVgFvc2eACy1n4WCtwjyjt32azTodJ1TN7nASKh0TdqzsZDDKh2ErtSoKItcuqDpHgRdF+G7Ovl0OJpe+64J9MgNOrFf8RrKjTyVMyt6kKf6RaxshuEyXiF7IhJCQKyxRzz2G3RQUdB6M3ZSi7TD6xLfs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771894515; c=relaxed/simple; bh=U8dRdtvZcYyWcRaAsd+lFSbNG2mMRb2eHiWi+yh8UNs=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=jxdfMNDHss6fg0cRYA4OAOPtUlWvo08S7g2I8LhmMlC+nj4mVbQk7enJ/ihUIQCYlgxc8oRkmwkL3aw+POumvrdCEZpE3yMcItvDcaax87d+57FRINYpedT1JapItSDggwABsyvpMxZVQjkoeSq+9x3ViCl9mxrvuvfF1cGzpdw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jmattson.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=QNgZtgH7; arc=none smtp.client-ip=209.85.214.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jmattson.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="QNgZtgH7" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2a7d7b87977so51874935ad.0 for ; Mon, 23 Feb 2026 16:55:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1771894513; x=1772499313; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=kw54h9TT8085zuh20vf9SBkAnbrWrd9JjgAMyyfoHIE=; b=QNgZtgH7EkSsUYLrS4NcQGLDnYgYZcPKojIQlmta5GD8dlRC149fYW7zJaIVy5pQv2 IdeRRgvO0Kklu1nd1g4Eln3IvIVoqwfdg5k9LyIL1N6H3A1iQTQij36mJWW+BEqcSJto J0qP6NkJqBETtPxNZn9CyjxUvzJU39s6lB9sEFaD1mtPsoIpqgrKq/YegowwL0SK0oTS NUH53RuuTvIxAk9Od6nzwjqXxKjWHO+1dzVObYd/DSqEAKWh7LH0gL3FzbmlUn2ExCi3 pPLwA1vQPPnhETzmagrmDw4elMc22DkIl+++2Ohfz9CyPzMoyRFONEFkL4aIYBBcA+7/ BpQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771894513; x=1772499313; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=kw54h9TT8085zuh20vf9SBkAnbrWrd9JjgAMyyfoHIE=; b=pEZXDY3RR3qXkAdmIqf3em9iD61yge7Z0dMfzDVUeiPL28B+MXJ5WGBd1VdrLGapXb sqykK4Rxh/oRqr0LI/Vacn884kw0vdq+1bj86KRTGoXBR7l63fsoCCK2ROpOZKwZq5pI XwFeIy00XH07PWe8dW6xKNl1wOrFQ3aDbCTeuAsnE3zaVSzGfILsm15/dfDibcaht1Hk vvM4qggkosBnMZEoUxlygggG74GZ3wtShADANbOJxCCe/KyD18DL/b4JzX8cj9XYLfb4 yaOw+Yxyf9Urdy/OXXXB6XyjH8w2kVeuccCWGVwypZJ/bIsV6Rg3cuAMbrNcaGLsa849 Imfw== X-Forwarded-Encrypted: i=1; AJvYcCWYvmCctU2sEpXuxLgHKMwfyscSvlvguytD55cKBNQN1kZZZYx9ZAUoeQPA4dNw2gGu0so94PBOxlpA3+g=@vger.kernel.org X-Gm-Message-State: AOJu0Yyyn7TBjxVpjnMFboJDit4XE+63po1jdH1q1ALtGxVxISKFQNVP bTPMrotsAjiG4Qa3Y8vOjXImpTid1u7cKpcpvvZSZQQJpQt0Dk+Q74qbjh6BrQbS0D9YroJ//ha 9kWtOG5JU+O3P/g== X-Received: from pjbev14.prod.google.com ([2002:a17:90a:eace:b0:356:3104:ed7]) (user=jmattson job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:e544:b0:2ad:9421:6136 with SMTP id d9443c01a7336-2ad942166b9mr10617865ad.1.1771894512864; Mon, 23 Feb 2026 16:55:12 -0800 (PST) Date: Mon, 23 Feb 2026 16:54:41 -0800 In-Reply-To: <20260224005500.1471972-1-jmattson@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260224005500.1471972-1-jmattson@google.com> X-Mailer: git-send-email 2.53.0.371.g1d285c8824-goog Message-ID: <20260224005500.1471972-4-jmattson@google.com> Subject: [PATCH v5 03/10] KVM: x86: nSVM: Cache and validate vmcb12 g_pat From: Jim Mattson To: Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Shuah Khan , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Yosry Ahmed Cc: Jim Mattson Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Cache g_pat from vmcb12 in vmcb_save_area_cached to avoid TOCTTOU issues, and add a validity check so that when nested paging is enabled for vmcb12, an invalid g_pat at emulated VMRUN causes an immediate VMEXIT with exit code VMEXIT_INVALID, as specified in the APM, volume 2: "Nested Paging and VMRUN/VMEXIT." Fixes: 3d6368ef580a ("KVM: SVM: Add VMRUN handler") Signed-off-by: Jim Mattson --- arch/x86/kvm/svm/nested.c | 17 +++++++++++++---- arch/x86/kvm/svm/svm.h | 1 + 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index b72a1f3c4144..91b35adb83f8 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -426,7 +426,8 @@ static bool nested_vmcb_check_controls(struct kvm_vcpu = *vcpu, =20 /* Common checks that apply to both L1 and L2 state. */ static bool nested_vmcb_check_save(struct kvm_vcpu *vcpu, - struct vmcb_save_area_cached *save) + struct vmcb_save_area_cached *save, + bool check_gpat) { if (CC(!(save->efer & EFER_SVME))) return false; @@ -462,6 +463,9 @@ static bool nested_vmcb_check_save(struct kvm_vcpu *vcp= u, if (CC(!kvm_valid_efer(vcpu, save->efer))) return false; =20 + if (check_gpat && CC(!kvm_pat_valid(save->g_pat))) + return false; + return true; } =20 @@ -573,6 +577,7 @@ static void __nested_copy_vmcb_save_to_cache(struct vmc= b_save_area_cached *to, =20 to->rax =3D from->rax; to->cr2 =3D from->cr2; + to->g_pat =3D from->g_pat; =20 svm_copy_lbrs(to, from); } @@ -1036,7 +1041,8 @@ int enter_svm_guest_mode(struct kvm_vcpu *vcpu, u64 v= mcb12_gpa, bool from_vmrun) =20 enter_guest_mode(vcpu); =20 - if (!nested_vmcb_check_save(vcpu, &svm->nested.save) || + if (!nested_vmcb_check_save(vcpu, &svm->nested.save, + nested_npt_enabled(svm)) || !nested_vmcb_check_controls(vcpu, &svm->nested.ctl, svm->vmcb01.ptr->save.cr0)) return -EINVAL; @@ -2006,13 +2012,16 @@ static int svm_set_nested_state(struct kvm_vcpu *vc= pu, =20 /* * Validate host state saved from before VMRUN (see - * nested_svm_check_permissions). + * nested_svm_check_permissions). Note that the g_pat field is not + * validated, because (a) it may have been clobbered by SMM before + * KVM_GET_NESTED_STATE, and (b) it is not loaded at emulated + * #VMEXIT. */ __nested_copy_vmcb_save_to_cache(&save_cached, save); if (!(save->cr0 & X86_CR0_PG) || !(save->cr0 & X86_CR0_PE) || (save->rflags & X86_EFLAGS_VM) || - !nested_vmcb_check_save(vcpu, &save_cached)) + !nested_vmcb_check_save(vcpu, &save_cached, false)) goto out_free; =20 =20 diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 9850ed01e16e..a49c48459e0b 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -161,6 +161,7 @@ struct vmcb_save_area_cached { u64 isst_addr; u64 rax; u64 cr2; + u64 g_pat; u64 dbgctl; u64 br_from; u64 br_to; --=20 2.53.0.371.g1d285c8824-goog