linux-kernel - [PATCH] x86: kvm: Restrict X86_FEATURE_VMMCALL to x86

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Date:   Mon, 30 Jul 2018 15:40:59 -0400
From:   Matthew Whitehead <tedheadster@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Matthew Whitehead <tedheadster@...il.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH] x86: kvm: Restrict X86_FEATURE_VMMCALL to x86_64 platform

early_init_amd() is called on all AMD processors, both 64 and 32 bit.
Presently 32 bit processors get the X86_FEATURE_VMMCALL feature set, which
they do not support. Add conditionals to restrict it to 64 bit processors.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Matthew Whitehead <tedheadster@...il.com>
---
 arch/x86/kernel/cpu/amd.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 38915fbfae73..df06919324cd 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -662,12 +662,14 @@ static void early_init_amd(struct cpuinfo_x86 *c)
 	}
 #endif
 
+#ifdef CONFIG_X86_64
 	/*
 	 * This is only needed to tell the kernel whether to use VMCALL
 	 * and VMMCALL.  VMMCALL is never executed except under virt, so
 	 * we can set it unconditionally.
 	 */
 	set_cpu_cap(c, X86_FEATURE_VMMCALL);
+#endif
 
 	/* F16h erratum 793, CVE-2013-6885 */
 	if (c->x86 == 0x16 && c->x86_model <= 0xf)
-- 
2.16.1