From: David Edmondson <david.edmondson@oracle.com>
To: Sean Christopherson <seanjc@google.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Joerg Roedel <joro@8bytes.org>,
Wanpeng Li <wanpengli@tencent.com>,
Borislav Petkov <bp@alien8.de>, Jim Mattson <jmattson@google.com>,
Ingo Molnar <mingo@redhat.com>,
Joao Martins <joao.m.martins@oracle.com>,
Aaron Lewis <aaronlewis@google.com>
Subject: Re: [PATCH 5/6] KVM: SVM: pass a proper reason in kvm_emulate_instruction()
Date: Tue, 13 Apr 2021 11:53:30 +0100 [thread overview]
Message-ID: <cuno8eisbf9.fsf@oracle.com> (raw)
In-Reply-To: <YHRvchkUSIeU8tRR@google.com>
On Monday, 2021-04-12 at 16:04:02 GMT, Sean Christopherson wrote:
> +Aaron
>
> On Mon, Apr 12, 2021, David Edmondson wrote:
>> From: Joao Martins <joao.m.martins@oracle.com>
>>
>> Declare various causes of emulation and use them as appropriate.
>>
>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
>> Signed-off-by: David Edmondson <david.edmondson@oracle.com>
>> ---
>> arch/x86/include/asm/kvm_host.h | 6 ++++++
>> arch/x86/kvm/svm/avic.c | 3 ++-
>> arch/x86/kvm/svm/svm.c | 26 +++++++++++++++-----------
>> 3 files changed, 23 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index 79e9ca756742..e1284680cbdc 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -1535,6 +1535,12 @@ enum {
>> EMULREASON_IO_COMPLETE,
>> EMULREASON_UD,
>> EMULREASON_PF,
>> + EMULREASON_SVM_NOASSIST,
>> + EMULREASON_SVM_RSM,
>> + EMULREASON_SVM_RDPMC,
>> + EMULREASON_SVM_CR,
>> + EMULREASON_SVM_DR,
>> + EMULREASON_SVM_AVIC_UNACCEL,
>
> Passing these to userspace arguably makes them ABI, i.e. they need to go into
> uapi/kvm.h somewhere. That said, I don't like passing arbitrary values for what
> is effectively the VM-Exit reason. Why not simply pass the exit reason, assuming
> we do indeed want to dump this info to userspace?
That would suffice, yes.
> What is the intended end usage of this information? Actual emulation? Debug?
> Logging?
Debug (which implies logging, given that I want this to happen on
systems that are in service).
> Depending on what you're trying to do with the info, maybe there's a better
> option. E.g. Aaron is working on a series that includes passing pass the code
> stream (instruction bytes) to userspace on emulation failure, though I'm not
> sure if he's planning on providing the VM-Exit reason.
Having the instruction stream will be good.
Aaron: do you have anything to share now? In what time frame do you
think you might submit patches?
I'm happy to re-work this to make the exit reason available, if that's
the appropriate direction.
dme.
--
And you're standing here beside me, I love the passing of time.
next prev parent reply other threads:[~2021-04-13 10:54 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-12 13:09 [PATCH 0/6] KVM: x86: Make the cause of instruction emulation available to user-space David Edmondson
2021-04-12 13:09 ` [PATCH 1/6] KVM: x86: add an emulation_reason to x86_emulate_instruction() David Edmondson
2021-04-12 13:09 ` [PATCH 2/6] KVM: x86: pass emulation_reason to handle_emulation_failure() David Edmondson
2021-04-12 13:09 ` [PATCH 3/6] KVM: x86: add emulation_reason to kvm_emulate_instruction() David Edmondson
2021-04-12 13:09 ` [PATCH 4/6] KVM: x86: pass a proper reason " David Edmondson
2021-04-12 13:09 ` [PATCH 5/6] KVM: SVM: pass a proper reason in kvm_emulate_instruction() David Edmondson
2021-04-12 16:04 ` Sean Christopherson
2021-04-13 10:53 ` David Edmondson [this message]
2021-04-13 18:45 ` Aaron Lewis
2021-04-14 12:25 ` David Edmondson
2021-04-12 13:09 ` [PATCH 6/6] KVM: VMX: " David Edmondson
2021-04-12 18:34 ` [PATCH 0/6] KVM: x86: Make the cause of instruction emulation available to user-space Jim Mattson
2021-04-13 10:54 ` David Edmondson
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