From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DFCFC303A07; Tue, 31 Mar 2026 17:06:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774976773; cv=none; b=dPqJsIue50Y1KYXuPQumYVar00qBTXygEd48n6eCj6Co1nLbC0exfRPAKaIpzQld/suxtKEZ5RplUi+jS5nXl84nctGF3dlfMhBDHWj9aI9ngDhJK8EydYAwtP7+FIAGjciYHj5IfvVswbRVkW2ykeuYEjen5+FV9O/taAIDuyo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774976773; c=relaxed/simple; bh=DG+Tq7TXBDLni+0NPm1kb08gc8zWFHlK95QCba7HkDc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Z3vtFo+ZKS8FT7ooTugzkUciPp4k7CnvmDMJCLPGQVjesgYuuvesAX84Riy1Xkz7QaaqFnPCmppgpKnXG49s5ZdUV0rrRcqgoNfcYIiJttQYpWPPKDXOuKd9DCvMMhS5nee3n0Kxs6Sg/ZRhcUxZ4bryXHYl/t5LJmKimGWTDCU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CDrvcq0n; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CDrvcq0n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73366C19423; Tue, 31 Mar 2026 17:06:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774976773; bh=DG+Tq7TXBDLni+0NPm1kb08gc8zWFHlK95QCba7HkDc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CDrvcq0n9hUROnecbvGPwSLlUqXB8ujY2+xZA5mCN60mAuiUPEwag21zh3GndHvIB LxqyAms9dnkEpqslkbTK+ytKQ874kfovbuzSyZPmHEL2/45KBLPv8xU+v6G2YhJtTM LDjEkexnG0Kf95RQch1yAx6N8aXS+PKHcvFdIwpY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alexander Bulekov , Fred Griffoul , Sean Christopherson Subject: [PATCH 6.18 222/309] KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE Date: Tue, 31 Mar 2026 18:22:05 +0200 Message-ID: <20260331161801.617771557@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260331161753.468533260@linuxfoundation.org> References: <20260331161753.468533260@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sean Christopherson commit aad885e774966e97b675dfe928da164214a71605 upstream. When installing an emulated MMIO SPTE, do so *after* dropping/zapping the existing SPTE (if it's shadow-present). While commit a54aa15c6bda3 was right about it being impossible to convert a shadow-present SPTE to an MMIO SPTE due to a _guest_ write, it failed to account for writes to guest memory that are outside the scope of KVM. E.g. if host userspace modifies a shadowed gPTE to switch from a memslot to emulted MMIO and then the guest hits a relevant page fault, KVM will install the MMIO SPTE without first zapping the shadow-present SPTE. ------------[ cut here ]------------ is_shadow_present_pte(*sptep) WARNING: arch/x86/kvm/mmu/mmu.c:484 at mark_mmio_spte+0xb2/0xc0 [kvm], CPU#0: vmx_ept_stale_r/4292 Modules linked in: kvm_intel kvm irqbypass CPU: 0 UID: 1000 PID: 4292 Comm: vmx_ept_stale_r Not tainted 7.0.0-rc2-eafebd2d2ab0-sink-vm #319 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:mark_mmio_spte+0xb2/0xc0 [kvm] Call Trace: mmu_set_spte+0x237/0x440 [kvm] ept_page_fault+0x535/0x7f0 [kvm] kvm_mmu_do_page_fault+0xee/0x1f0 [kvm] kvm_mmu_page_fault+0x8d/0x620 [kvm] vmx_handle_exit+0x18c/0x5a0 [kvm_intel] kvm_arch_vcpu_ioctl_run+0xc55/0x1c20 [kvm] kvm_vcpu_ioctl+0x2d5/0x980 [kvm] __x64_sys_ioctl+0x8a/0xd0 do_syscall_64+0xb5/0x730 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x47fa3f ---[ end trace 0000000000000000 ]--- Reported-by: Alexander Bulekov Debugged-by: Alexander Bulekov Suggested-by: Fred Griffoul Fixes: a54aa15c6bda3 ("KVM: x86/mmu: Handle MMIO SPTEs directly in mmu_set_spte()") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/mmu/mmu.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3044,12 +3044,6 @@ static int mmu_set_spte(struct kvm_vcpu bool prefetch = !fault || fault->prefetch; bool write_fault = fault && fault->write; - if (unlikely(is_noslot_pfn(pfn))) { - vcpu->stat.pf_mmio_spte_created++; - mark_mmio_spte(vcpu, sptep, gfn, pte_access); - return RET_PF_EMULATE; - } - if (is_shadow_present_pte(*sptep)) { if (prefetch && is_last_spte(*sptep, level) && pfn == spte_to_pfn(*sptep)) @@ -3073,6 +3067,14 @@ static int mmu_set_spte(struct kvm_vcpu was_rmapped = 1; } + if (unlikely(is_noslot_pfn(pfn))) { + vcpu->stat.pf_mmio_spte_created++; + mark_mmio_spte(vcpu, sptep, gfn, pte_access); + if (flush) + kvm_flush_remote_tlbs_gfn(vcpu->kvm, gfn, level); + return RET_PF_EMULATE; + } + wrprot = make_spte(vcpu, sp, slot, pte_access, gfn, pfn, *sptep, prefetch, false, host_writable, &spte);