From: Rudolf Marek <r.marek@assembler.cz>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org
Cc: andy Lutomirski <luto@amacapital.net>,
Borislav Petkov <bp@suse.de>, lkml <linux-kernel@vger.kernel.org>
Subject: [PATCH] x86: make X86_BUG_FXSAVE_LEAK detectable in CPUID on AMD
Date: Tue, 28 Nov 2017 22:01:06 +0100
Message-ID: <bdcebe90-62c5-1f05-083c-eba7f08b2540@assembler.cz> (raw)
In-Reply-To: <20171119103001.ncjck5wbzaqyqewo@pd.tnic>
The latest AMD AMD64 Architecture Programmer's Manual
adds a CPUID feature XSaveErPtr (CPUID_Fn80000008_EBX[2]).
If this feature is set, the FXSAVE, XSAVE, FXSAVEOPT, XSAVEC, XSAVES
/ FXRSTOR, XRSTOR, XRSTORS always save/restore error pointers,
thus making the X86_BUG_FXSAVE_LEAK workaround obsolete on such CPUs.
Signed-Off-By: Rudolf Marek <r.marek@assembler.cz>
Reviewed-and-tested-by: Borislav Petkov <bp@suse.de>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/kernel/cpu/amd.c | 7 +++++--
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index c0b0e9e..800104c 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -266,6 +266,7 @@
/* AMD-defined CPU features, CPUID level 0x80000008 (EBX), word 13 */
#define X86_FEATURE_CLZERO (13*32+ 0) /* CLZERO instruction */
#define X86_FEATURE_IRPERF (13*32+ 1) /* Instructions Retired Count */
+#define X86_FEATURE_XSAVEERPTR (13*32+ 2) /* Always save/restore FP error pointers */
/* Thermal and Power Management Leaf, CPUID level 0x00000006 (EAX), word 14 */
#define X86_FEATURE_DTHERM (14*32+ 0) /* Digital Thermal Sensor */
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index d58184b..bcb75dc 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -804,8 +804,11 @@ static void init_amd(struct cpuinfo_x86 *c)
case 0x17: init_amd_zn(c); break;
}
- /* Enable workaround for FXSAVE leak */
- if (c->x86 >= 6)
+ /*
+ * Enable workaround for FXSAVE leak on CPUs
+ * without a XSaveErPtr feature
+ */
+ if ((c->x86 >= 6) && (!cpu_has(c, X86_FEATURE_XSAVEERPTR)))
set_cpu_bug(c, X86_BUG_FXSAVE_LEAK);
cpu_detect_cache_sizes(c);
--
2.7.4
next parent reply index
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <558a0f66-002b-7365-9988-9877b95a2c31@assembler.cz>
[not found] ` <20171118180538.e7b5l4r2j5l5esjd@pd.tnic>
[not found] ` <4813068b-f669-5239-f3a4-6e57af77be4c@assembler.cz>
[not found] ` <20171119103001.ncjck5wbzaqyqewo@pd.tnic>
2017-11-28 21:01 ` Rudolf Marek [this message]
2017-11-29 9:34 ` [tip:x86/urgent] x86: Make " tip-bot for Rudolf Marek
2017-12-06 11:34 ` [tip:x86/urgent] x86/cpufeatures: " tip-bot for Rudolf Marek
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