linux-kernel - [PATCH] x86/sev: Check for MWAITX and MONITORX opcodes in the #VC handler

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date: Mon, 22 Apr 2024 08:39:21 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: <linux-kernel@...r.kernel.org>, <x86@...nel.org>
CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
	Michael Roth <michael.roth@....com>, Ashish Kalra <ashish.kalra@....com>,
	Joerg Roedel <jroedel@...e.de>, Adam Dunlap <acdunlap@...gle.com>, "Peter
 Gonda" <pgonda@...gle.com>
Subject: [PATCH] x86/sev: Check for MWAITX and MONITORX opcodes in the #VC handler

The MWAITX and MONITORX instructions generate the same #VC error code as
the MWAIT and MONITOR instructions, respectively. Update the #VC handler
opcode checking to also support the MWAITX and MONITORX opcodes.

Fixes: e3ef461af35a ("x86/sev: Harden #VC instruction emulation somewhat")
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kernel/sev-shared.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index 8b04958da5e7..b4f8fa0f722c 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -1203,12 +1203,14 @@ static enum es_result vc_check_opcode_bytes(struct es_em_ctxt *ctxt,
 		break;
 
 	case SVM_EXIT_MONITOR:
-		if (opcode == 0x010f && modrm == 0xc8)
+		/* MONITOR and MONITORX instructions generate the same error code */
+		if (opcode == 0x010f && (modrm == 0xc8 || modrm == 0xfa))
 			return ES_OK;
 		break;
 
 	case SVM_EXIT_MWAIT:
-		if (opcode == 0x010f && modrm == 0xc9)
+		/* MWAIT and MWAITX instructions generate the same error code */
+		if (opcode == 0x010f && (modrm == 0xc9 || modrm == 0xfb))
 			return ES_OK;
 		break;
 
-- 
2.43.2