From: Gavin Shan <gshan@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>, Marc Zyngier <maz@kernel.org>
Cc: catalin.marinas@arm.com, linux-kernel@vger.kernel.org,
shan.gavin@gmail.com, will@kernel.org,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH RFCv2 9/9] arm64: Support async page fault
Date: Tue, 2 Jun 2020 15:44:42 +1000 [thread overview]
Message-ID: <fca52ea1-294a-6011-45f1-d0df30069800@redhat.com> (raw)
In-Reply-To: <5c72c597-732e-7dbf-d056-665674ec1792@redhat.com>
Hi Marc, Paolo,
On 6/1/20 7:21 PM, Paolo Bonzini wrote:
> On 31/05/20 14:44, Marc Zyngier wrote:
>>>
>>> Is there an ARM-approved way to reuse the S2 fault syndromes to detect
>>> async page faults?
>>
>> It would mean being able to set an ESR_EL2 register value into ESR_EL1,
>> and there is nothing in the architecture that would allow that,
>
> I understand that this is not what you want to do and I'm not proposing
> it, but I want to understand this better: _in practice_ do CPUs check
> closely what is written in ESR_EL1?
>
> In any case, the only way to implement this, it seems to me, would be a
> completely paravirtualized exception vector that doesn't use ESR at all.
>
> On the other hand, for the page ready (interrupt) side assigning a PPI
> seems complicated but doable.
>
Marc suggested to use SDEI in another reply. I think it might be the
appropriate way to deliver page-not-present. To some extent, it could
be regarded as exception, which doesn't use ESR at all. It matches with
what Paolo is thinking of: paravirtualized exception vector that doesn't
use ESR at all. However, it seems it's not supported in kvm-arm yet. So
I assume it needs to be developed from scratch. Marc, could you please
help to confirm? Thanks in advance.
I agree with Paolo PPI (interrupt) might be the best way to deliver
page-ready currently. I don't think SDEI is suitable because there
are no big difference between SDEI and currently used DABT injection
to some extent. With SDEI, We will have the issues we are facing.
For example, some critical code section isn't safe to receive SDEI
if I'm correct.
Thanks,
Gavin
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next prev parent reply other threads:[~2020-06-02 5:44 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-08 3:29 [PATCH RFCv2 0/9] kvm/arm64: Support Async Page Fault Gavin Shan
2020-05-08 3:29 ` [PATCH RFCv2 1/9] arm64: Probe for the presence of KVM hypervisor services during boot Gavin Shan
2020-05-08 3:29 ` [PATCH RFCv2 2/9] arm/arm64: KVM: Advertise KVM UID to guests via SMCCC Gavin Shan
2020-05-08 3:29 ` [PATCH RFCv2 3/9] kvm/arm64: Rename kvm_vcpu_get_hsr() to kvm_vcpu_get_esr() Gavin Shan
2020-05-26 10:42 ` Mark Rutland
2020-05-27 2:43 ` Gavin Shan
2020-05-27 7:20 ` Marc Zyngier
2020-05-28 6:34 ` Gavin Shan
2020-05-08 3:29 ` [PATCH RFCv2 4/9] kvm/arm64: Detach ESR operator from vCPU struct Gavin Shan
2020-05-26 10:51 ` Mark Rutland
2020-05-27 2:55 ` Gavin Shan
2020-05-08 3:29 ` [PATCH RFCv2 5/9] kvm/arm64: Replace hsr with esr Gavin Shan
2020-05-26 10:45 ` Mark Rutland
2020-05-27 2:56 ` Gavin Shan
2020-05-08 3:29 ` [PATCH RFCv2 6/9] kvm/arm64: Export kvm_handle_user_mem_abort() with prefault mode Gavin Shan
2020-05-26 10:58 ` Mark Rutland
2020-05-27 3:01 ` Gavin Shan
2020-05-08 3:29 ` [PATCH RFCv2 7/9] kvm/arm64: Support async page fault Gavin Shan
2020-05-26 12:34 ` Mark Rutland
2020-05-27 4:05 ` Gavin Shan
2020-05-27 7:37 ` Marc Zyngier
2020-05-28 6:32 ` Gavin Shan
2020-05-08 3:29 ` [PATCH RFCv2 8/9] kernel/sched: Add cpu_rq_is_locked() Gavin Shan
2020-05-08 3:29 ` [PATCH RFCv2 9/9] arm64: Support async page fault Gavin Shan
2020-05-26 12:56 ` Mark Rutland
2020-05-27 6:48 ` Paolo Bonzini
2020-05-28 6:14 ` Gavin Shan
2020-05-28 7:03 ` Marc Zyngier
2020-05-28 10:53 ` Paolo Bonzini
2020-05-28 10:48 ` Paolo Bonzini
2020-05-28 23:02 ` Gavin Shan
2020-05-29 9:41 ` Marc Zyngier
2020-05-29 11:11 ` Paolo Bonzini
2020-05-31 12:44 ` Marc Zyngier
2020-06-01 9:21 ` Paolo Bonzini
2020-06-02 5:44 ` Gavin Shan [this message]
2020-05-25 23:39 ` [PATCH RFCv2 0/9] kvm/arm64: Support Async Page Fault Gavin Shan
2020-05-26 13:09 ` Mark Rutland
2020-05-27 2:39 ` Gavin Shan
2020-05-27 7:48 ` Marc Zyngier
2020-05-27 16:10 ` Paolo Bonzini
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