From: Jim Mattson <jmattson@google.com>
Date: Sun, 13 May 2018 21:33:57 +0000 (-0400)
Subject: x86/cpu: Make alternative_msr_write work for 32-bit code
X-Git-Tag: Ubuntu-4.13.0-45.50~25
X-Git-Url: https://git.proxmox.com/?p=mirror_ubuntu-artful-kernel.git;a=commitdiff_plain;h=9fb38c68eefba014374acdc9fb3f171b69559cfa

x86/cpu: Make alternative_msr_write work for 32-bit code

Cast val and (val >> 32) to (u32), so that they fit in a
general-purpose register in both 32-bit and 64-bit code.

[ tglx: Made it u32 instead of uintptr_t ]

Fixes: c65732e4f721 ("x86/cpu: Restore CPUID_8000_0008_EBX reload")
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>

CVE-2018-3639 (x86)

(cherry-picked from commit 5f2b745f5e1304f438f9b2cd03ebc8120b6e0d3b)
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 5ce68e3e5bc9..ef7d5bf5d079 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -189,8 +189,8 @@ void alternative_msr_write(unsigned int msr, u64 val, unsigned int feature)
 {
 	asm volatile(ALTERNATIVE("", "wrmsr", %c[feature])
 		: : "c" (msr),
-		    "a" (val),
-		    "d" (val >> 32),
+		    "a" ((u32)val),
+		    "d" ((u32)(val >> 32)),
 		    [feature] "i" (feature)
 		: "memory");
 }