2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: "Roedel, Joerg" <[email protected]> commit d47cc0db8fd6011de2248df505fc34990b7451bf upstream. 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]> Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> Signed-off-by: Andi Kleen <[email protected]> --- arch/x86/kernel/cpu/amd.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) Index: linux-2.6.35.y/arch/x86/kernel/cpu/amd.c =================================================================== --- linux-2.6.35.y.orig/arch/x86/kernel/cpu/amd.c +++ linux-2.6.35.y/arch/x86/kernel/cpu/amd.c @@ -585,10 +585,13 @@ static void __cpuinit init_amd(struct cp * 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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