From: Paolo Bonzini <pbonzini@redhat.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Kashyap Chamarthy <kashyap.cv@gmail.com>,
Gleb Natapov <gleb@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [nvmx testing, linux on linux] Disabling EPT in L1 renders L2 stuck on boot
Date: Tue, 08 Oct 2013 16:48:05 +0200 [thread overview]
Message-ID: <52541B25.504@redhat.com> (raw)
In-Reply-To: <52540298.2030807@redhat.com>
Il 08/10/2013 15:03, Paolo Bonzini ha scritto:
> Il 08/10/2013 07:38, Kashyap Chamarthy ha scritto:
>> On Mon, Oct 7, 2013 at 6:29 PM, Kashyap Chamarthy <kashyap.cv@gmail.com> wrote:
>>> Gleb, so I just did a trace of KVM MMU to try to understand why L2 is
>>> stuck with shadow on EPT
>>
>> Paolo, were you able to reproduce this again? Yesterday, on #qemu you
>> mentioned you'll test it again :-)
>
> Yes, I could reproduce it too.
>
>>> Boot L2 guest:
>
> Here L2 doesn't go past the second instruction. It gets a page fault
> even though the spte is present, and KVM then loops on a page fault
> for 0xfe05b.
>
> Here is an annotated function_graph trace of L1.
>
> It's possible that L0 is injecting the same fault repeatedly, i.e.
> they are not different faults from the processor. I'll get an L0
> trace next.
>
The L0 trace is not particularly helpful (and probably would not be
particularly helpful even if there were a specific tracepoint for
VMREAD):
287.534156: kvm_exit: reason VMRESUME rip 0xffffffffa021f8d1 info 0 0
287.534160: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 0sync
287.534161: kvm_entry: vcpu 0
287.534162: kvm_exit: reason EXCEPTION_NMI rip 0xe05b info fe05b 80000b0e
287.534170: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 0sync
287.534171: kvm_entry: vcpu 0
287.534172: kvm_exit: reason VMREAD rip 0xffffffffa021f97d info 0 0
287.534173: kvm_entry: vcpu 0
287.534174: kvm_exit: reason VMREAD rip 0xffffffffa021f996 info 0 0
287.534174: kvm_entry: vcpu 0
287.534175: kvm_exit: reason VMREAD rip 0xffffffffa021f9b5 info 0 0
287.534175: kvm_entry: vcpu 0
287.534177: kvm_exit: reason VMREAD rip 0xffffffffa021b377 info 0 0
287.534177: kvm_entry: vcpu 0
287.534178: kvm_exit: reason VMREAD rip 0xffffffffa021b5ce info 0 0
287.534179: kvm_entry: vcpu 0
287.534180: kvm_exit: reason VMREAD rip 0xffffffffa0222c95 info 0 0
287.534180: kvm_entry: vcpu 0
287.534181: kvm_exit: reason VMREAD rip 0xffffffffa0222e1c info 0 0
287.534182: kvm_entry: vcpu 0
287.534185: kvm_exit: reason MSR_READ rip 0xffffffff8104c2b6 info 0 0
287.534185: kvm_msr: msr_read 1d9 = 0x0
287.534185: kvm_entry: vcpu 0
And then it repeats:
287.534186: kvm_exit: reason VMRESUME rip 0xffffffffa021f8d1 info 0 0
287.534191: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 0sync
287.534192: kvm_entry: vcpu 0
Trying to add function_graph loses a lot of events.
Paolo
next prev parent reply other threads:[~2013-10-08 14:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-04 8:31 [nvmx testing, linux on linux] Disabling EPT in L1 renders L2 stuck on boot Kashyap Chamarthy
2013-10-04 9:33 ` Kashyap Chamarthy
2013-10-04 9:39 ` Gleb Natapov
2013-10-04 12:33 ` Kashyap Chamarthy
2013-10-04 13:05 ` Gleb Natapov
2013-10-04 13:08 ` Gleb Natapov
2013-10-04 15:28 ` Kashyap Chamarthy
2013-10-07 12:59 ` Kashyap Chamarthy
2013-10-07 15:18 ` Gleb Natapov
2013-10-08 5:38 ` Kashyap Chamarthy
2013-10-08 13:03 ` Paolo Bonzini
2013-10-08 14:48 ` Paolo Bonzini [this message]
2013-10-09 6:22 ` Kashyap Chamarthy
2013-10-09 8:16 ` Gleb Natapov
2013-10-09 17:46 ` Kashyap Chamarthy
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