commit: d47cc0db8fd6011de2248df505fc34990b7451bf
From: "Roedel, Joerg" <[email protected]>
Date: Thu, 19 May 2011 11:13:39 +0200
Subject: [PATCH] x86, amd: Use _safe() msr access for GartTlbWlk disable code
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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 <[email protected]>
Signed-off-by: Joerg Roedel <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Maciej Rutecki <[email protected]>
Cc: Avi Kivity <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: <[email protected]> # .39.x
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/kernel/cpu/amd.c | 9 ++++++---
1 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 6f9d1f6..8f5cabb 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);
+ }
}
}
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