From d47cc0db8fd6011de2248df505fc34990b7451bf Mon Sep 17 00:00:00 2001 From: "Roedel, Joerg" Date: Thu, 19 May 2011 11:13:39 +0200 Subject: [PATCH] x86, amd: Use _safe() msr access for GartTlbWlk disable code MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The workaround for Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=33012 introduced a read and a write to the MC4 mask msr. Unfortunatly this MSR is not emulated by the KVM hypervisor so that the kernel will get a #GP and crashes when applying this workaround when running inside KVM. This issue was reported as: https://bugzilla.kernel.org/show_bug.cgi?id=35132 and is fixed with this patch. The change just let the kernel ignore any #GP it gets while accessing this MSR by using the _safe msr access methods. Reported-by: Török Edwin Signed-off-by: Joerg Roedel Cc: Rafael J. Wysocki Cc: Maciej Rutecki Cc: Avi Kivity Cc: Andrew Morton Cc: # .39.x Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/amd.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 6f9d1f6..8f5cabb3 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -629,10 +629,13 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c) * Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=33012 */ u64 mask; + int err; - rdmsrl(MSR_AMD64_MCx_MASK(4), mask); - mask |= (1 << 10); - wrmsrl(MSR_AMD64_MCx_MASK(4), mask); + err = rdmsrl_safe(MSR_AMD64_MCx_MASK(4), &mask); + if (err == 0) { + mask |= (1 << 10); + checking_wrmsrl(MSR_AMD64_MCx_MASK(4), mask); + } } } -- 2.7.4