From: Paolo Bonzini <pbonzini@redhat.com>
To: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>,
rkrcmar@redhat.com, joro@8bytes.org, bp@alien8.de,
gleb@kernel.org, alex.williamson@redhat.com
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
wei@redhat.com, sherry.hurwitz@amd.com
Subject: Re: [PART1 RFC v2 05/10] KVM: x86: Detect and Initialize AVIC support
Date: Wed, 16 Mar 2016 08:20:35 +0100 [thread overview]
Message-ID: <56E90943.3060100@redhat.com> (raw)
In-Reply-To: <56E8FB8B.7050700@amd.com>
On 16/03/2016 07:22, Suravee Suthikulpanit wrote:
> This is mainly causing a large number of VMEXIT due to NPF.
Got it, it's here in the manual: "System software is responsible for
setting up a translation in the nested page table granting guest read
and write permissions for accesses to the vAPIC Backing Page in SPA
space. AVIC hardware walks the nested page table to check permissions,
but does not use the SPA address specified in the leaf page table entry.
Instead, AVIC hardware finds this address in the AVIC_BACKING_PAGE
pointer field of the VMCB".
Strictly speaking the address of the 0xFEE00000 translation is
unnecessary and it could be all zeroes, but I suggest that you set up an
APIC access page like Intel does (4k only), using the special memslot.
The AVIC backing page can then point to lapic->regs.
Thanks for the explanation!
Paolo
> CASE1: Using x86_set_memory_region() for AVIC backing page
>
> # ./perf-vmexit.sh 10
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 2.813 MB perf.data.guest (30356
> samples) ]
>
>
> Analyze events for all VMs, all VCPUs:
>
> VM-EXIT Samples Samples% Time% Min Time Max
> Time Avg time
>
> interrupt 10042 66.30% 81.33% 0.43us
> 202.50us 7.43us ( +- 1.20% )
> msr 5004 33.04% 15.76% 0.73us
> 12.21us 2.89us ( +- 0.43% )
> pause 58 0.38% 0.18% 0.56us
> 5.88us 2.92us ( +- 6.43% )
> npf 35 0.23% 2.01% 6.41us
> 207.78us 52.70us ( +- 23.67% )
> nmi 4 0.03% 0.02% 2.31us
> 4.67us 3.49us ( +- 14.26% )
> io 3 0.02% 0.70% 82.75us
> 360.90us 214.28us ( +- 37.64% )
> avic_incomp_ipi 1 0.01% 0.00% 2.17us
> 2.17us 2.17us ( +- 0.00% )
>
> Total Samples:15147, Total events handled time:91715.78us.
>
>
> CASE2: Using the lapic regs page for AVIC backing page.
>
> # ./perf-vmexit.sh 10
> [ perf record: Woken up 255 times to write data ]
> [ perf record: Captured and wrote 509.202 MB perf.data.guest (5718856
> samples) ]
>
>
> Analyze events for all VMs, all VCPUs:
>
> VM-EXIT Samples Samples% Time% Min Time Max
> Time Avg time
>
> npf 1897710 99.33% 98.08% 1.09us
> 243.22us 1.67us ( +- 0.04% )
> interrupt 7818 0.41% 1.44% 0.44us
> 216.55us 5.97us ( +- 1.92% )
> msr 5001 0.26% 0.45% 0.68us
> 12.58us 2.89us ( +- 0.50% )
> pause 25 0.00% 0.00% 0.71us
> 4.23us 2.03us ( +- 10.76% )
> io 4 0.00% 0.03% 73.91us
> 337.29us 206.74us ( +- 26.38% )
> nmi 1 0.00% 0.00% 5.92us
> 5.92us 5.92us ( +- 0.00% )
>
> Total Samples:1910559, Total events handled time:3229214.64us.
>
> Thanks,
> Suravee
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next prev parent reply other threads:[~2016-03-16 7:20 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-04 20:45 [PART1 RFC v2 00/10] KVM: x86: Introduce SVM AVIC support Suravee Suthikulpanit
2016-03-04 20:45 ` [PART1 RFC v2 01/10] KVM: x86: Misc LAPIC changes to exposes helper functions Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 02/10] KVM: x86: Introducing kvm_x86_ops VCPU blocking/unblocking Suravee Suthikulpanit
2016-03-07 15:42 ` Paolo Bonzini
2016-03-14 6:19 ` Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 03/10] svm: Introduce new AVIC VMCB registers Suravee Suthikulpanit
2016-03-07 15:44 ` Paolo Bonzini
2016-03-14 7:41 ` Suravee Suthikulpanit
2016-03-14 12:25 ` Paolo Bonzini
2016-03-15 12:51 ` Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 04/10] svm: clean up V_TPR, V_IRQ, V_INTR_PRIO, and V_INTR_MASKING Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 05/10] KVM: x86: Detect and Initialize AVIC support Suravee Suthikulpanit
2016-03-07 16:41 ` Paolo Bonzini
2016-03-15 17:09 ` Suravee Suthikulpanit
2016-03-15 17:22 ` Paolo Bonzini
2016-03-16 6:22 ` Suravee Suthikulpanit
2016-03-16 7:20 ` Paolo Bonzini [this message]
2016-03-16 8:21 ` Suravee Suthikulpanit
2016-03-16 11:12 ` Paolo Bonzini
2016-03-04 20:46 ` [PART1 RFC v2 06/10] svm: Add interrupt injection via AVIC Suravee Suthikulpanit
2016-03-07 15:36 ` Paolo Bonzini
2016-03-08 21:54 ` Radim Krčmář
2016-03-09 11:10 ` Paolo Bonzini
2016-03-09 16:00 ` Radim Krčmář
2016-03-14 9:41 ` Suravee Suthikulpanit
2016-03-14 12:27 ` Paolo Bonzini
2016-03-14 9:50 ` Suravee Suthikulpanit
2016-03-14 5:25 ` Suravee Suthikulpanit
2016-03-14 8:54 ` Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 07/10] svm: Add VMEXIT handlers for AVIC Suravee Suthikulpanit
2016-03-07 15:58 ` Paolo Bonzini
2016-03-08 22:05 ` Radim Krčmář
2016-03-09 10:56 ` Paolo Bonzini
2016-03-09 20:55 ` Radim Krčmář
2016-03-10 19:34 ` Radim Krčmář
2016-03-10 19:54 ` Paolo Bonzini
2016-03-10 20:44 ` Radim Krčmář
2016-03-17 3:58 ` Suravee Suthikulpanit
2016-03-17 9:35 ` Paolo Bonzini
2016-03-17 19:44 ` Suravee Suthikulpanit
2016-03-17 20:27 ` [PATCH] KVM: split kvm_vcpu_wake_up from kvm_vcpu_kick Radim Krčmář
2016-03-18 5:13 ` Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 08/10] svm: Do not expose x2APIC when enable AVIC Suravee Suthikulpanit
2016-03-04 20:46 ` [PART1 RFC v2 09/10] svm: Do not intercept CR8 " Suravee Suthikulpanit
2016-03-07 15:39 ` Paolo Bonzini
2016-03-14 6:09 ` Suravee Suthikulpanit
2016-03-14 12:28 ` Paolo Bonzini
2016-03-04 20:46 ` [PART1 RFC v2 10/10] svm: Manage vcpu load/unload " Suravee Suthikulpanit
2016-03-09 21:46 ` Radim Krčmář
2016-03-10 14:01 ` Radim Krčmář
2016-03-14 11:58 ` Suravee Suthikulpanit
2016-03-14 16:54 ` Radim Krčmář
2016-03-14 11:48 ` Suravee Suthikulpanit
2016-03-14 16:40 ` Radim Krčmář
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