From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751636AbaHRObt (ORCPT ); Mon, 18 Aug 2014 10:31:49 -0400 Received: from mail-la0-f54.google.com ([209.85.215.54]:33913 "EHLO mail-la0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750834AbaHRObr convert rfc822-to-8bit (ORCPT ); Mon, 18 Aug 2014 10:31:47 -0400 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Subject: Re: [PATCH] KVM: x86: Increase the number of fixed MTRR regs to 10 From: Nadav Amit In-Reply-To: Date: Mon, 18 Aug 2014 17:31:41 +0300 Cc: Nadav Amit , "gleb@kernel.org" , "tglx@linutronix.de" , "mingo@redhat.com" , "hpa@zytor.com" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" Content-Transfer-Encoding: 8BIT Message-Id: References: <1403101279-23759-1-git-send-email-namit@cs.technion.ac.il> <20140818021715.GA7019@kernel> <20140818081115.GA26307@kernel> To: Wanpeng Li , "pbonzini@redhat.com" X-Mailer: Apple Mail (2.1878.6) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 wrote: > I reproduced the blue-screen. Let me to to figure it out. > > Nadav > > On Aug 18, 2014, at 11:11 AM, Wanpeng Li 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 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 >>>>> --- >>>>> 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@vger.kernel.org >>>>> 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@vger.kernel.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >