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From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org
Cc: KVM list <kvm@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org, xen-devel <Xen-devel@lists.xen.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andy Lutomirski <luto@kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arjan van de Ven <arjan@linux.intel.com>,
	Ingo Molnar <mingo@kernel.org>
Subject: [PATCH v2 2/2] x86/msr: Set the return value to zero when native_rdmsr_safe fails
Date: Sun, 20 Sep 2015 17:02:56 -0700	[thread overview]
Message-ID: <b9a0176d31979e0bcd9fe324d7dcb6f0baac9177.1442793572.git.luto__38219.5020247765$1442793890$gmane$org@kernel.org> (raw)
In-Reply-To: <cover.1442793572.git.luto@kernel.org>
In-Reply-To: <cover.1442793572.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 77d8b284e4a7..9eda52205d42 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -73,7 +73,10 @@ 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)
-- 
2.4.3

  parent reply	other threads:[~2015-09-21  0:02 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <cover.1442793572.git.luto@kernel.org>
2015-09-21  0:02 ` [PATCH v2 1/2] x86/msr: Carry on after a non-"safe" MSR access fails without !panic_on_oops Andy Lutomirski
2015-09-21  0:02 ` Andy Lutomirski [this message]
     [not found] ` <130a3b7ef4788baae3a6fe71293ab17442bc9a0a.1442793572.git.luto@kernel.org>
2015-09-21  0:15   ` Linus Torvalds
     [not found]   ` <CA+55aFy4Chd-PJvxGne=TztPsvFqUG07Ht8mtc4+0oGNZNDOyw@mail.gmail.com>
2015-09-21  1:13     ` Andy Lutomirski
     [not found]     ` <CALCETrXqsKcqzfqMO2ctOJJ4X8Kb6vvoUpVDir9F2-a3XwK23w@mail.gmail.com>
2015-09-21  8:46       ` Ingo Molnar
     [not found]       ` <20150921084642.GA30984@gmail.com>
2015-09-21 12:27         ` Paolo Bonzini
2015-09-21 16:36         ` Linus Torvalds
     [not found]         ` <CA+55aFzKCi6pf0RP8HjDQYDsms6reB5AihuCAHEkVJtoOHk_Yw@mail.gmail.com>
2015-09-21 16:49           ` Arjan van de Ven
     [not found]           ` <56003506.1050100@linux.intel.com>
2015-09-21 17:27             ` Linus Torvalds
2015-09-21 17:43             ` Andy Lutomirski
     [not found]             ` <CALCETrUSEm_QLxGaBdmy3tQn=WnagvzTaYpy+i14sGUeaOUvTQ@mail.gmail.com>
2015-09-22  8:12               ` Paolo Bonzini
2015-09-21 18:16           ` Andy Lutomirski
     [not found]           ` <CALCETrUBcDxvtjKC-m97GPwCOHvcoDdGjnMJLukSue8ha55mng@mail.gmail.com>
2015-09-21 18:36             ` Borislav Petkov
2015-09-21 18:47             ` Linus Torvalds
2015-09-22  7:14           ` Ingo Molnar
2015-09-30 13:10           ` Peter Zijlstra
     [not found]           ` <20150930131002.GK2881@worktop.programming.kicks-ass.net>
2015-09-30 14:01             ` Ingo Molnar
     [not found]             ` <20150930140122.GB3285@gmail.com>
2015-09-30 18:04               ` Andy Lutomirski
     [not found]               ` <CALCETrVMV2_3ywQ_t+0rsqzxMm6D9PvDEmOdrie67rRzfj-W_Q@mail.gmail.com>
2015-10-01  7:15                 ` Ingo Molnar
     [not found]                 ` <20151001071505.GA21542@gmail.com>
2016-03-11 16:48                   ` Andy Lutomirski
     [not found]                   ` <CALCETrUFakwGL9zpj9TwKX9KbG9czq8fpEViU3nWaCvnpGurew@mail.gmail.com>
2016-03-12 16:02                     ` Ingo Molnar
2015-09-30 18:32           ` H. Peter Anvin

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