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 73DE9376BDE for ; Thu, 20 Nov 2025 15:51:42 +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=1763653902; cv=none; b=hTbeytBQHojOQEjywuOAK9lQB548DS2HlYRZQ2UCQS1WHEy37PGG/aSABjShDNzv8jp5hJiIiECa+unzeqpRUphpgP/fbdfUAKU9uKPKoQcVg2tcBewb+pomKPsXK70ZelcGkOCudm2vbpn8EXtzxkxm/UdzVDNY5vXJSBkoC1A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763653902; c=relaxed/simple; bh=G6m7yeA+Vu0waM0SYZG1uGcZNz5IwgJlAzCDTqpHrt0=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=QACR8752sktmG/zB+uRARILpHLBy7vfv9J0oTDHcXv5pT7CyKuc7TOnZ4Sar1kCF6JA41xUYQIuinHQHWOVBHzcbFNT1MUxyDw6bWuOvDmdOBcV4f4DvpxSFrwNMU8nNLK+i9geeq9E+uZCORyFZgS5cDdvoB+/sgPQDu+3GCGU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=TgqABaNn; 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="TgqABaNn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0DCEC4CEF1; Thu, 20 Nov 2025 15:51:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1763653902; bh=G6m7yeA+Vu0waM0SYZG1uGcZNz5IwgJlAzCDTqpHrt0=; h=Subject:To:Cc:From:Date:From; b=TgqABaNnHYwsDxRKUu1hlJUkO7e4nkia2JsKILLse6CnlnXH9OSSC91cGScgRT+rc waFm4uDv+U/Uvw9IwHu8BFWjBfIttMxBX2cK4hucql17uY0HH6Z7SIuSFmCUMd4OpU rgSBT+XEyWoms+CgKujnIxJx+JUHb4LVmLcg8DH8= Subject: FAILED: patch "[PATCH] KVM: VMX: Inject #UD if guest tries to execute SEAMCALL or" failed to apply to 5.15-stable tree To: seanjc@google.com,binbin.wu@linux.intel.com,dan.j.williams@intel.com,kai.huang@intel.com,rick.p.edgecombe@intel.com,xiaoyao.li@intel.com Cc: From: Date: Thu, 20 Nov 2025 16:51:31 +0100 Message-ID: <2025112031-cod-monsoon-9a49@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 9d7dfb95da2cb5c1287df2f3468bcb70d8b31087 # git commit -s git send-email --to '' --in-reply-to '2025112031-cod-monsoon-9a49@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 9d7dfb95da2cb5c1287df2f3468bcb70d8b31087 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 16 Oct 2025 11:21:47 -0700 Subject: [PATCH] KVM: VMX: Inject #UD if guest tries to execute SEAMCALL or TDCALL MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add VMX exit handlers for SEAMCALL and TDCALL to inject a #UD if a non-TD guest attempts to execute SEAMCALL or TDCALL. Neither SEAMCALL nor TDCALL is gated by any software enablement other than VMXON, and so will generate a VM-Exit instead of e.g. a native #UD when executed from the guest kernel. Note! No unprivileged DoS of the L1 kernel is possible as TDCALL and SEAMCALL #GP at CPL > 0, and the CPL check is performed prior to the VMX non-root (VM-Exit) check, i.e. userspace can't crash the VM. And for a nested guest, KVM forwards unknown exits to L1, i.e. an L2 kernel can crash itself, but not L1. Note #2! The Intel® Trust Domain CPU Architectural Extensions spec's pseudocode shows the CPL > 0 check for SEAMCALL coming _after_ the VM-Exit, but that appears to be a documentation bug (likely because the CPL > 0 check was incorrectly bundled with other lower-priority #GP checks). Testing on SPR and EMR shows that the CPL > 0 check is performed before the VMX non-root check, i.e. SEAMCALL #GPs when executed in usermode. Note #3! The aforementioned Trust Domain spec uses confusing pseudocode that says that SEAMCALL will #UD if executed "inSEAM", but "inSEAM" specifically means in SEAM Root Mode, i.e. in the TDX-Module. The long- form description explicitly states that SEAMCALL generates an exit when executed in "SEAM VMX non-root operation". But that's a moot point as the TDX-Module injects #UD if the guest attempts to execute SEAMCALL, as documented in the "Unconditionally Blocked Instructions" section of the TDX-Module base specification. Cc: stable@vger.kernel.org Cc: Kai Huang Cc: Xiaoyao Li Cc: Rick Edgecombe Cc: Dan Williams Cc: Binbin Wu Reviewed-by: Kai Huang Reviewed-by: Binbin Wu Reviewed-by: Xiaoyao Li Link: https://lore.kernel.org/r/20251016182148.69085-2-seanjc@google.com Signed-off-by: Sean Christopherson diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h index 9792e329343e..1baa86dfe029 100644 --- a/arch/x86/include/uapi/asm/vmx.h +++ b/arch/x86/include/uapi/asm/vmx.h @@ -93,6 +93,7 @@ #define EXIT_REASON_TPAUSE 68 #define EXIT_REASON_BUS_LOCK 74 #define EXIT_REASON_NOTIFY 75 +#define EXIT_REASON_SEAMCALL 76 #define EXIT_REASON_TDCALL 77 #define EXIT_REASON_MSR_READ_IMM 84 #define EXIT_REASON_MSR_WRITE_IMM 85 diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 76271962cb70..bcea087b642f 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -6728,6 +6728,14 @@ static bool nested_vmx_l1_wants_exit(struct kvm_vcpu *vcpu, case EXIT_REASON_NOTIFY: /* Notify VM exit is not exposed to L1 */ return false; + case EXIT_REASON_SEAMCALL: + case EXIT_REASON_TDCALL: + /* + * SEAMCALL and TDCALL unconditionally VM-Exit, but aren't + * virtualized by KVM for L1 hypervisors, i.e. L1 should + * never want or expect such an exit. + */ + return false; default: return true; } diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index f87c216d976d..91b6f2f3edc2 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6032,6 +6032,12 @@ static int handle_vmx_instruction(struct kvm_vcpu *vcpu) return 1; } +static int handle_tdx_instruction(struct kvm_vcpu *vcpu) +{ + kvm_queue_exception(vcpu, UD_VECTOR); + return 1; +} + #ifndef CONFIG_X86_SGX_KVM static int handle_encls(struct kvm_vcpu *vcpu) { @@ -6157,6 +6163,8 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = { [EXIT_REASON_ENCLS] = handle_encls, [EXIT_REASON_BUS_LOCK] = handle_bus_lock_vmexit, [EXIT_REASON_NOTIFY] = handle_notify, + [EXIT_REASON_SEAMCALL] = handle_tdx_instruction, + [EXIT_REASON_TDCALL] = handle_tdx_instruction, [EXIT_REASON_MSR_READ_IMM] = handle_rdmsr_imm, [EXIT_REASON_MSR_WRITE_IMM] = handle_wrmsr_imm, };