Re: [PATCH 0/8] KVM: x86: Interrupt-based mechanism for async_pf 'page present' notifications

From: Vivek Goyal <vgoyal@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: kvm@vger.kernel.org, x86@kernel.org,
	Paolo Bonzini <pbonzini@redhat.com>,
	Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Jim Mattson <jmattson@google.com>, Gavin Shan <gshan@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/8] KVM: x86: Interrupt-based mechanism for async_pf 'page present' notifications
Date: Tue, 12 May 2020 11:32:09 -0400	[thread overview]
Message-ID: <20200512153209.GC138129@redhat.com> (raw)
In-Reply-To: <20200511164752.2158645-1-vkuznets@redhat.com>

Hi Vitaly,

Are there any corresponding qemu patches as well to enable new
functionality. Wanted to test it.

Thanks
Vivek

On Mon, May 11, 2020 at 06:47:44PM +0200, 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 RFC:
> - Using #PF for 'page ready' is deprecated and removed [Paolo Bonzini]
> - 'reason' field in 'struct kvm_vcpu_pv_apf_data' is not used for 'page ready'
>   notifications and 'pageready_token' is not used for 'page not present' events
>   [Paolo Bonzini]
> - Renamed MSR_KVM_ASYNC_PF2 -> MSR_KVM_ASYNC_PF_INT [Peter Xu]
> - Drop 'enabled' field from MSR_KVM_ASYNC_PF_INT [Peter Xu]
> - Other minor changes supporting the above.
> 
> Vitaly Kuznetsov (8):
>   Revert "KVM: async_pf: Fix #DF due to inject "Page not Present" and
>     "Page Ready" exceptions simultaneously"
>   KVM: x86: extend struct kvm_vcpu_pv_apf_data with token info
>   KVM: introduce kvm_read_guest_offset_cached()
>   KVM: x86: interrupt based APF page-ready event delivery
>   KVM: x86: acknowledgment mechanism for async pf page ready
>     notifications
>   KVM: x86: announce KVM_FEATURE_ASYNC_PF_INT
>   KVM: x86: Switch KVM guest to using interrupts for page ready APF
>     delivery
>   KVM: x86: drop KVM_PV_REASON_PAGE_READY case from
>     kvm_handle_page_fault()
> 
>  Documentation/virt/kvm/cpuid.rst     |   6 ++
>  Documentation/virt/kvm/msr.rst       | 106 ++++++++++++++------
>  arch/s390/include/asm/kvm_host.h     |   2 +
>  arch/x86/entry/entry_32.S            |   5 +
>  arch/x86/entry/entry_64.S            |   5 +
>  arch/x86/include/asm/hardirq.h       |   3 +
>  arch/x86/include/asm/irq_vectors.h   |   6 +-
>  arch/x86/include/asm/kvm_host.h      |   7 +-
>  arch/x86/include/asm/kvm_para.h      |   6 ++
>  arch/x86/include/uapi/asm/kvm_para.h |  11 ++-
>  arch/x86/kernel/irq.c                |   9 ++
>  arch/x86/kernel/kvm.c                |  42 ++++++--
>  arch/x86/kvm/cpuid.c                 |   3 +-
>  arch/x86/kvm/mmu/mmu.c               |  10 +-
>  arch/x86/kvm/x86.c                   | 142 ++++++++++++++++++---------
>  include/linux/kvm_host.h             |   3 +
>  include/uapi/linux/kvm.h             |   1 +
>  virt/kvm/async_pf.c                  |  10 ++
>  virt/kvm/kvm_main.c                  |  19 +++-
>  19 files changed, 295 insertions(+), 101 deletions(-)
> 
> -- 
> 2.25.4
> 