From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Lutomirski 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 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: In-Reply-To: References: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: x86@kernel.org Cc: KVM list , Peter Zijlstra , Linus Torvalds , linux-kernel@vger.kernel.org, xen-devel , Thomas Gleixner , Andy Lutomirski , Paolo Bonzini , Andrew Morton , Arjan van de Ven , Ingo Molnar List-Id: xen-devel@lists.xenproject.org This will cause unchecked native_rdmsr_safe failures to return deterministic results. Signed-off-by: Andy Lutomirski --- 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