From: Andy Lutomirski <luto@kernel.org>
To: X86 ML <x86@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
KVM list <kvm@vger.kernel.org>,
Arjan van de Ven <arjan@linux.intel.com>,
xen-devel <Xen-devel@lists.xen.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v3 5/5] x86/msr: Set the return value to zero when native_rdmsr_safe fails
Date: Fri, 11 Mar 2016 11:06:50 -0800 [thread overview]
Message-ID: <da2fb9b15bac0bd6a28676c51fb67966287b2490.1457723023.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1457723023.git.luto@kernel.org>
In-Reply-To: <cover.1457723023.git.luto@kernel.org>
This will cause unchecked native_rdmsr_safe failures to return
deterministic results.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/include/asm/msr.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 13da359881d7..e97e79f8a22b 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -109,7 +109,10 @@ static inline unsigned long long native_read_msr_safe(unsigned int msr,
asm volatile("2: rdmsr ; xor %[err],%[err]\n"
"1:\n\t"
".section .fixup,\"ax\"\n\t"
- "3: mov %[fault],%[err] ; jmp 1b\n\t"
+ "3: mov %[fault],%[err]\n\t"
+ "xorl %%eax, %%eax\n\t"
+ "xorl %%edx, %%edx\n\t"
+ "jmp 1b\n\t"
".previous\n\t"
_ASM_EXTABLE(2b, 3b)
: [err] "=r" (*err), EAX_EDX_RET(val, low, high)
--
2.5.0
prev parent reply other threads:[~2016-03-11 19:07 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-11 19:06 [PATCH v3 0/5] Improve non-"safe" MSR access failure handling Andy Lutomirski
2016-03-11 19:06 ` [PATCH v3 1/5] x86/paravirt: Add _safe to the read_msr and write_msr PV hooks Andy Lutomirski
2016-03-11 19:06 ` [PATCH v3 2/5] x86/msr: Carry on after a non-"safe" MSR access fails without !panic_on_oops Andy Lutomirski
2016-03-12 15:31 ` Ingo Molnar
2016-03-12 15:36 ` Ingo Molnar
2016-03-12 17:32 ` Andy Lutomirski
2016-03-11 19:06 ` [PATCH v3 3/5] x86/paravirt: Add paravirt_{read,write}_msr Andy Lutomirski
2016-03-14 14:02 ` Paolo Bonzini
2016-03-14 16:53 ` Andy Lutomirski
[not found] ` <CA+55aFzdUHUTomsMU7YAYgYkUQvNXHAiNX765wdSFqrKyoLKpQ@mail.gmail.com>
2016-03-14 17:02 ` Andy Lutomirski
2016-03-15 8:49 ` Paolo Bonzini
2016-03-15 8:56 ` Paolo Bonzini
2016-03-11 19:06 ` [PATCH v3 4/5] x86/paravirt: Make "unsafe" MSR accesses unsafe even if PARAVIRT=y Andy Lutomirski
2016-03-11 19:06 ` Andy Lutomirski [this message]
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