linux-kernel - [PATCH 3/7] x86/sev: Require the RMPREAD instruction after Fam19h

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

Date: Mon, 24 Jun 2024 09:37:07 -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>
Subject: [PATCH 3/7] x86/sev: Require the RMPREAD instruction after Fam19h

Limit usage of the non-architectural RMP format to Fam19h processors.
The RMPREAD instruction, with its architecture defined output, is
available, and should be used, for RMP access beyond Fam19h.

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kernel/cpu/amd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index be5889bded49..0b39249640ee 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -358,7 +358,8 @@ static void bsp_determine_snp(struct cpuinfo_x86 *c)
 		 * for which the RMP table entry format is currently defined for.
 		 */
 		if (!cpu_has(c, X86_FEATURE_HYPERVISOR) &&
-		    c->x86 >= 0x19 && snp_probe_rmptable_info()) {
+		    (c->x86 == 0x19 || cpu_feature_enabled(X86_FEATURE_RMPREAD)) &&
+		    snp_probe_rmptable_info()) {
 			cc_platform_set(CC_ATTR_HOST_SEV_SNP);
 		} else {
 			setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
-- 
2.43.2