linux-kernel - Re: [PATCH v2 00/10] KVM: x86: Interrupt-based mechanism for async

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Message-ID: <3be1df67-2e39-c7b7-b666-66cd4fe61406@redhat.com>
Date:   Thu, 28 May 2020 13:04:55 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org,
        x86@...nel.org
Cc:     Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jim Mattson <jmattson@...gle.com>,
        Vivek Goyal <vgoyal@...hat.com>, Gavin Shan <gshan@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 00/10] KVM: x86: Interrupt-based mechanism for async_pf
 'page present' notifications

On 25/05/20 16:41, Vitaly Kuznetsov wrote:
> Concerns were expressed around (ab)using #PF for KVM's async_pf mechanism,
> it seems that re-using #PF exception for a PV mechanism wasn't a great
> idea after all. The Grand Plan is to switch to using e.g. #VE for 'page
> not present' events and normal APIC interrupts for 'page ready' events.
> This series does the later.
> 
> Changes since v1:
> - struct kvm_vcpu_pv_apf_data's fields renamed to 'flags' and 'token',
>   comments added [Vivek Goyal]
> - 'type1/2' names for APF events dropped from everywhere [Vivek Goyal]
> - kvm_arch_can_inject_async_page_present() renamed to 
>   kvm_arch_can_dequeue_async_page_present [Vivek Goyal]
> - 'KVM: x86: deprecate KVM_ASYNC_PF_SEND_ALWAYS' patch added.
> 
> v1: https://lore.kernel.org/kvm/20200511164752.2158645-1-vkuznets@redhat.com/
> QEMU patches for testing: https://github.com/vittyvk/qemu.git (async_pf2_v2 branch)

I'll do another round of review and queue patches 1-7; 8-9 will be
queued later and separately due to the conflicts with the interrupt
entry rework, but it's my job and you don't need to do anything else.

Thanks,

Paolo