From: Alexander Graf <agraf@suse.de>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"joerg.roedel@amd.com" <joerg.roedel@amd.com>
Subject: Re: [PATCH] KVM: MMU: Segregate mmu pages created with different cr4.pge settings
Date: Fri, 9 Jan 2009 11:43:05 +0100 [thread overview]
Message-ID: <349E5291-0516-4F27-AD5F-0A7C4A94D276@suse.de> (raw)
In-Reply-To: <20090109003644.GA4706@amt.cnet>
On 09.01.2009, at 01:36, Marcelo Tosatti <mtosatti@redhat.com> wrote:
> On Thu, Jan 08, 2009 at 08:53:21PM +0100, Alexander Graf wrote:
>> Sorry for the late reply - I wanted to know who kvm hangs in the host
>> kernel context :)
>>
>> On 07.01.2009, at 14:46, Marcelo Tosatti <mtosatti@redhat.com> wrote:
>>
>>> On Wed, Jan 07, 2009 at 01:32:41PM +0200, Avi Kivity wrote:
>>>> Marcelo Tosatti wrote:
>>>>> Let me shoot at one direction: a shadow page with PGE bit in
>>>>> either
>>>>> state is created. Later that shadow page is nuked (via mmu
>>>>> notifiers,
>>>>> for example).
>>>>
>>>> I doubt that mmu notifiers were invoked in this case (the bug would
>>>> be
>>>> very rare); in any case we flush the tlb.
>>>
>>> This comment is worrying
>>>
>>> /*
>>> * FIXME: Tis shouldn't be necessary here, but there is a
>>> flush
>>> * missing in the MMU code. Until we find this bug, flush the
>>> * complete TLB here on an NPF
>>> */
>>> if (npt_enabled)
>>> svm_flush_tlb(&svm->vcpu);
>>>
>>
>> This is in, because netbench in an npt-guest failed after a few
>> minutes
>> (see Alex W's bug report) and this appeard to fix it.
>
> Right. The comment is scary, thats all. Maybe the hypothetical missing
> flush is also the cause for this bug you're not. Or not.
>
>>> Alexander, you might want to try this patch, -ENONPT here (and
>>> revert
>>> the previous
>>> one).
>>
>> Eh, what?
>
> I meant I have no NPT box to test myself easily.
Ah, what a pity :o
>
> "revert the previous one" = remove the !tdp_enabled test on set_cr4.
>
> The patch below is just a hack to flush the TLB of remote vcpu's
> before
> updating the host TLB. To confirm an experimental theory (read:
> guess).
Ok, will do.
>
>
> Hum, NPT is surely not available inside the guest for ESX to use?
Npt can only be used with SVM, and I haven't seen esx call svm
instructions at all so far.
Alex
> Yeah, gathering more information would be helpful.
>
>>> I have no clue, what else could be causing this?
>>>
>>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>>> index 10bdb2a..bf68e5b 100644
>>> --- a/arch/x86/kvm/mmu.c
>>> +++ b/arch/x86/kvm/mmu.c
>>> @@ -33,6 +33,7 @@
>>> #include <asm/cmpxchg.h>
>>> #include <asm/io.h>
>>> #include <asm/vmx.h>
>>> +#include <asm/tlbflush.h>
>>>
>>> /*
>>> * When setting this variable to true it enables Two-Dimensional-
>>> Paging
>>> @@ -1850,6 +1851,11 @@ static int __direct_map(struct kvm_vcpu
>>> *vcpu,
>>> gpa_t v, int write,
>>>
>>> if (*iterator.sptep == shadow_trap_nonpresent_pte) {
>>> pseudo_gfn = (iterator.addr & PT64_DIR_BASE_ADDR_MASK) >>
>>> PAGE_SHIFT;
>>> +
>>> + kvm_flush_remote_tlbs(vcpu->kvm);
>>> + kvm_mmu_flush_tlb(vcpu);
>>> + __flush_tlb();
>>> +
>>> sp = kvm_mmu_get_page(vcpu, pseudo_gfn, iterator.addr,
>>> iterator.level - 1,
>>> 1, ACC_ALL, iterator.sptep);
>>> --
>>> 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
next prev parent reply other threads:[~2009-01-09 10:43 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20081221184146.8E00B250012@cleopatra.tlv.redhat.com>
2009-01-05 14:56 ` [PATCH] KVM: MMU: Segregate mmu pages created with different cr4.pge settings Alexander Graf
2009-01-06 10:41 ` Avi Kivity
2009-01-06 14:11 ` Marcelo Tosatti
2009-01-06 14:29 ` Avi Kivity
2009-01-06 15:06 ` Marcelo Tosatti
2009-01-06 16:43 ` Marcelo Tosatti
2009-01-07 6:49 ` Alexander Graf
2009-01-07 10:19 ` Avi Kivity
2009-01-07 10:43 ` Marcelo Tosatti
2009-01-07 11:32 ` Avi Kivity
2009-01-07 13:46 ` Marcelo Tosatti
2009-01-08 19:53 ` Alexander Graf
2009-01-09 0:36 ` Marcelo Tosatti
2009-01-09 10:43 ` Alexander Graf [this message]
2009-01-11 9:12 Marcelo Tosatti
2009-01-11 9:20 ` Avi Kivity
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