From mboxrd@z Thu Jan 1 00:00:00 1970 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 44117337111 for ; Thu, 12 Feb 2026 15:59:16 +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=1770911957; cv=none; b=sc3LksAA6IG+mPlZVydiiFAQFO5nLRr0w8Ex7a3Hs5zPBxJE6s28c0xlqVjKxboCgsTSUrhRsO2kRe4EMYvmOqLbMveQLlt7T1w5DIBWDMJ+vX6zoOJ/uv/wYCkBrIRdAWaaUCmEDdTHkC11I0r/xHMOk7np8VXlArYRPKu3M5w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770911957; c=relaxed/simple; bh=0pkG637PPrMnHAp36dNXBDpeM+jikBZBFutLvS3Rhns=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Rk5lyp5tHDNKDbegBIaFGtAyXIJjiFog1nUI7Zan+6slDrpkWXF7l86648Ul3S/1UhD7x/kSU5DIiEOqiVDMQe+rFM7LfhavxW/VnpbXoAM4VBCX0LGnCk4HFkjqOHPONyYAPmTOoQRS4sDPE+QDLdO7kSGFB1wfHvcrhd1Sq5I= 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=fl/VG49g; 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="fl/VG49g" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2aae0d40a47so446555ad.2 for ; Thu, 12 Feb 2026 07:59:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1770911956; x=1771516756; 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=Zf8WWkIBl7yhW0Oc6MyZTF76PTkFmwYWfgFxHjbq7+4=; b=fl/VG49gVN/F8pdVQNA06z9p8j+5wbrNAWug/wXdtGfScySTyqVCcSrRO4fzTt70B1 n9fnId1lscpIn+0LlqtumdZ6gyslwpfX1x9wXMeeVpBe80yA90PEsMaRp1X5O3UdhPMj wiP4cK+3A0Q3M5seoGXc2BGCMbwEY+EUdRjYXflIAZdVayzrMAl1fLX9mdWd6d2wTDr/ 8QecPr14ztkTUu3REcITEQjP2EeOEB89XFPYRenDLgi70YM9tjFQtSBfdeHRtAuJ+nuH hXQNEvE7CZryMBTOz3/H6+Xcl6QsccW839SUEJ+OuQxhMpC9nS0xh+48yJHMB9zsERS4 x81Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770911956; x=1771516756; 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=Zf8WWkIBl7yhW0Oc6MyZTF76PTkFmwYWfgFxHjbq7+4=; b=o8/SoV/fPkbbcE3ZZPcU9GOUiZeJTyxaXH8FnfhP4vJBiQThdaURioqQ4+nPcdePOw OtokIdG37KB4SZWKc6LyZ9PmCVIhBJxieUK0BWeAKjV0ObhLXj9jbWquR6027npvnISb +EYVt8FcxGZrmu2rO8XZg1V4zmxLgRLxtZGx5IFoQ/HSjK4aBpej+C3f/7OOPo9U3yNa h5xu2GKmTnwsCJIplW8i+8mCK9yLiVv/8LOitAdvCT3P9t283j73jq38dSJ5czvqwkC2 DzwTlmQMAHq+IYfGBj1+YUp0vONC8r0G6YN2cM7yXJ1kDUFv3i82Bgwhy3dJ1reMw9Yg UMQw== X-Forwarded-Encrypted: i=1; AJvYcCUGkOQCaT/VmiQiV4dex+GFf/K7vfSEjAd24fhxrGbmmI6T0LOTUqE5TMLuUCWdIlrDfTPdn3Iq5mit9JDDb8Q=@vger.kernel.org X-Gm-Message-State: AOJu0YyZx6rmQf7qtG0dGdKkuZOsK8UbEvF3roqautxec0iR50Jnupr0 EhkCm9o3kiG2ho6AfjWeu4/50thQk06l9Bm4Vr/pq6YeqCH344m9OYodtDrunF60KnP+Y4PJuxM ALZlJmK3Yq6INMg== X-Received: from plbkh12.prod.google.com ([2002:a17:903:64c:b0:2aa:d3c5:610d]) (user=jmattson job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:98b:b0:295:62d:5004 with SMTP id d9443c01a7336-2ab399dd629mr35532595ad.26.1770911955652; Thu, 12 Feb 2026 07:59:15 -0800 (PST) Date: Thu, 12 Feb 2026 07:58:50 -0800 In-Reply-To: <20260212155905.3448571-1-jmattson@google.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260212155905.3448571-1-jmattson@google.com> X-Mailer: git-send-email 2.53.0.239.g8d8fc8a987-goog Message-ID: <20260212155905.3448571-3-jmattson@google.com> Subject: [PATCH v4 2/8] 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-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, /* 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 *vcpu, if (CC(!kvm_valid_efer(vcpu, save->efer))) return false; + if (check_gpat && CC(!kvm_pat_valid(save->g_pat))) + return false; + return true; } @@ -573,6 +577,7 @@ static void __nested_copy_vmcb_save_to_cache(struct vmcb_save_area_cached *to, to->rax = from->rax; to->cr2 = from->cr2; + to->g_pat = from->g_pat; svm_copy_lbrs(to, from); } @@ -1036,7 +1041,8 @@ int enter_svm_guest_mode(struct kvm_vcpu *vcpu, u64 vmcb12_gpa, bool from_vmrun) enter_guest_mode(vcpu); - 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 *vcpu, /* * 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; 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; -- 2.53.0.239.g8d8fc8a987-goog