linux-kernel - Re: [PATCH] KVM: x86: Increase the number of fixed MTRR regs to 10

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Date:	Mon, 18 Aug 2014 10:17:15 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Nadav Amit <namit@...technion.ac.il>, pbonzini@...hat.com
Cc:	gleb@...nel.org, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Subject: Re: [PATCH] KVM: x86: Increase the number of fixed MTRR regs to 10

Hi Nadav,
On Wed, Jun 18, 2014 at 05:21:19PM +0300, Nadav Amit wrote:
>Recent Intel CPUs have 10 variable range MTRRs. Since operating systems
>sometime make assumptions on CPUs while they ignore capability MSRs, it is
>better for KVM to be consistent with recent CPUs. Reporting more MTRRs than
>actually supported has no functional implications.
>
>Signed-off-by: Nadav Amit <namit@...technion.ac.il>
>---
> 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 4931415..0bab29d 100644
>--- a/arch/x86/include/asm/kvm_host.h
>+++ b/arch/x86/include/asm/kvm_host.h
>@@ -95,7 +95,7 @@ static inline gfn_t gfn_to_index(gfn_t gfn, gfn_t base_gfn, int level)
> #define KVM_REFILL_PAGES 25
> #define KVM_MAX_CPUID_ENTRIES 80
> #define KVM_NR_FIXED_MTRR_REGION 88
>-#define KVM_NR_VAR_MTRR 8
>+#define KVM_NR_VAR_MTRR 10
> 

We observed that there is obvious regression caused by this commit, 32bit 
win7 guest show blue screen during boot.

Regards,
Wanpeng Li 

> #define ASYNC_PF_PER_VCPU 64
> 
>-- 
>1.9.1
>
>--
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