The cause for the blue-screen appears to be seabios, which leaves only 0x20 slots for “smp_mtrr”s. Apparently, the increase in the variable range MTRR count caused it to exhaust the available slots. As a result, some MSRs are not initialised by the BIOS (specifically, 3.5-4GB are not marked as UC), and cause Windows to panic. Once we increase the size of the array smp_mtrr in seabios, Windows boots. Paolo, you may wish to revert the patch. Please note that it was applied to some stable branches. Nadav On Aug 18, 2014, at 12:39 PM, Nadav Amit <nadav.amit@xxxxxxxxx> wrote: > I reproduced the blue-screen. Let me to to figure it out. > > Nadav > > On Aug 18, 2014, at 11:11 AM, Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx> wrote: > >> On Mon, Aug 18, 2014 at 09:39:39AM +0300, Nadav Amit wrote: >>> This should have been a benign patch. I'll try to get windows 7 installation disk and check ASAP. >>> >> >> In addition, it just can be reproduced on 32bit win7 w/ MP enabled, in >> case UP can't be reproduced. >> >> Regards, >> Wanpeng Li >> >>> Nadav >>> >>>> On 18 Aug 2014, at 05:17, Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx> wrote: >>>> >>>> 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@xxxxxxxxxxxxxxxxx> >>>>> --- >>>>> 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 >>>>> >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe kvm" in >>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe kvm" in >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
