linux-kernel - [PATCH] x86/CPU/AMD: Clear virtualized VMLOAD/VMSAVE on Zen4 client

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Message-ID: <20241105160234.1300702-1-superm1@kernel.org>
Date: Tue,  5 Nov 2024 10:02:34 -0600
From: Mario Limonciello <superm1@...nel.org>
To: Borislav Petkov <bp@...en8.de>
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	"H . Peter Anvin" <hpa@...or.com>,
	Nikolay Borisov <nik.borisov@...e.com>,
	Tom Lendacky <thomas.lendacky@....com>,
	Brijesh Singh <brijesh.singh@....com>,
	linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	Mario Limonciello <mario.limonciello@....com>
Subject: [PATCH] x86/CPU/AMD: Clear virtualized VMLOAD/VMSAVE on Zen4 client

From: Mario Limonciello <mario.limonciello@....com>

A number of Zen4 client SoCs advertise the ability to use virtualized
VMLOAD/VMSAVE, but using these instructions is reported to be a cause
of a random host reboot.

These instructions aren't intended to be advertised on Zen4 client
so clear the capability.

Cc: stable@...r.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219009
Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
 arch/x86/kernel/cpu/amd.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 015971adadfc7..ecd42c2b3242e 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -924,6 +924,17 @@ static void init_amd_zen4(struct cpuinfo_x86 *c)
 {
 	if (!cpu_has(c, X86_FEATURE_HYPERVISOR))
 		msr_set_bit(MSR_ZEN4_BP_CFG, MSR_ZEN4_BP_CFG_SHARED_BTB_FIX_BIT);
+
+	/*
+	 * These Zen4 SoCs advertise support for virtualized VMLOAD/VMSAVE
+	 * in some BIOS versions but they can lead to random host reboots.
+	 */
+	switch (c->x86_model) {
+	case 0x18 ... 0x1f:
+	case 0x60 ... 0x7f:
+		clear_cpu_cap(c, X86_FEATURE_V_VMSAVE_VMLOAD);
+		break;
+	}
 }
 
 static void init_amd_zen5(struct cpuinfo_x86 *c)
-- 
2.43.0