[PATCH 3.13 028/103] Revert "KVM: x86: Increase the number of fixed MTRR regs to 10"

Kamal Mostafa kamal at canonical.com
Tue Sep 30 21:30:33 UTC 2014 -stable review patch.  If anyone has any objections, please let me know.


From: Paolo Bonzini <pbonzini at redhat.com>

commit 0d234daf7e0a3290a3a20c8087eefbd6335a5bd4 upstream.

This reverts commit 682367c494869008eb89ef733f196e99415ae862,
which causes 32-bit SMP Windows 7 guests to panic.

SeaBIOS has a limit on the number of MTRRs that it can handle,
and this patch exceeded the limit.  Better revert it.
Thanks to Nadav Amit for debugging the cause.

Reported-by: Wanpeng Li <wanpeng.li at linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 arch/x86/include/asm/kvm_host.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c16aef8..2122ffb 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -99,7 +99,7 @@ static inline gfn_t gfn_to_index(gfn_t gfn, gfn_t base_gfn, int level)
 #define KVM_REFILL_PAGES 25
-#define KVM_NR_VAR_MTRR 10
+#define KVM_NR_VAR_MTRR 8
 #define ASYNC_PF_PER_VCPU 64

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