From mboxrd@z Thu Jan 1 00:00:00 1970 From: tip-bot for Andy Lutomirski Subject: [tip:x86/asm] x86/msr: Set the return value to zero when native_rdmsr_safe() fails Date: Wed, 13 Apr 2016 04:46:29 -0700 Message-ID: References: <515fb611449a755312a476cfe11675906e7ddf6c.1459605520.git.luto@kernel.org> Reply-To: torvalds@linux-foundation.org, pbonzini@redhat.com, bp@alien8.de, Xen-devel@lists.xen.org, luto@kernel.org, boris.ostrovsky@oracle.com, arjan@linux.intel.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mingo@kernel.org, kvm@vger.kernel.org, peterz@infradead.org, hpa@zytor.com, tglx@linutronix.de Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: tglx@linutronix.de, hpa@zytor.com, mingo@kernel.org, akpm@linux-foundation.org, kvm@vger.kernel.org, peterz@infradead.org, linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, arjan@linux.intel.com, luto@kernel.org, bp@alien8.de, Xen-devel@lists.xen.org, torvalds@linux-foundation.org, pbonzini@redhat.com To: linux-tip-commits@vger.kernel.org Return-path: In-Reply-To: <515fb611449a755312a476cfe11675906e7ddf6c.1459605520.git.luto@kernel.org> Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Commit-ID: b828b79fcced0e66492590707649dbfaea6435e6 Gitweb: http://git.kernel.org/tip/b828b79fcced0e66492590707649dbfaea6435e6 Author: Andy Lutomirski AuthorDate: Sat, 2 Apr 2016 07:01:40 -0700 Committer: Ingo Molnar CommitDate: Wed, 13 Apr 2016 11:37:46 +0200 x86/msr: Set the return value to zero when native_rdmsr_safe() fails This will cause unchecked native_rdmsr_safe() failures to return deterministic results. Tested-by: Boris Ostrovsky Signed-off-by: Andy Lutomirski Acked-by: Linus Torvalds Cc: Andrew Morton Cc: Arjan van de Ven Cc: Borislav Petkov Cc: KVM list Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: xen-devel Link: http://lkml.kernel.org/r/515fb611449a755312a476cfe11675906e7ddf6c.1459605520.git.luto@kernel.org Signed-off-by: Ingo Molnar --- 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 00050c0..7dc1d8f 100644 --- a/arch/x86/include/asm/msr.h +++ b/arch/x86/include/asm/msr.h @@ -101,7 +101,10 @@ 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)