From: Paolo Bonzini <pbonzini@redhat.com>
To: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
joro@8bytes.org, alex.williamson@redhat.com, gleb@kernel.org
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
wei@redhat.com, sherry.hurwitz@amd.com
Subject: Re: [PART1 RFC 0/9] KVM: x86: Introduce SVM AVIC support
Date: Fri, 12 Feb 2016 19:13:35 +0100 [thread overview]
Message-ID: <56BE20CF.8030708@redhat.com> (raw)
In-Reply-To: <1455285574-27892-1-git-send-email-suravee.suthikulpanit@amd.com>
I have a few questions about AVIC.
On 12/02/2016 14:59, Suravee Suthikulpanit wrote:
> CURRENT UNSUPPORT USE-CASES
> ===========================
> - Nested VM
> - VM Migration
I'm interested in what you mean with "VM migration". I've noticed that,
because x2APIC is disabled by default, it's possible that a VM on a
non-AVIC host will fail when moved to an AVIC host. I would prefer if
you kept x2APIC working through VMEXITs. Getting the full performance
benefit would require disabling x2APIC of course (or waiting for
improved support in the processor), but at least there would be no surprise.
Is it just this, or is there anything else?
(I'm quite surprised that x2APIC is not supported. MSRs are faster than
memory accesses due to the cost of TLB misses, which can be hefty for VMs).
I have a few other doubts about the architecture that hopefully you (or
Wei Huang too) can clarify before I can review this patch meaningfully.
I have replied to other patches with these questions.
Paolo
next prev parent reply other threads:[~2016-02-12 18:13 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-12 13:59 [PART1 RFC 0/9] KVM: x86: Introduce SVM AVIC support Suravee Suthikulpanit
2016-02-12 13:59 ` [PART1 RFC 1/9] KVM: x86: Misc LAPIC changes to exposes helper functions Suravee Suthikulpanit
2016-02-12 13:59 ` [PART1 RFC 2/9] svm: Introduce new AVIC VMCB registers Suravee Suthikulpanit
2016-02-12 13:59 ` [PART1 RFC 3/9] svm: clean up V_TPR, V_IRQ, V_INTR_PRIO, and V_INTR_MASKING Suravee Suthikulpanit
2016-02-12 13:59 ` [PART1 RFC 4/9] KVM: x86: Detect and Initialize AVIC support Suravee Suthikulpanit
2016-02-12 14:13 ` Borislav Petkov
2016-02-12 15:46 ` Suravee Suthikulpanit
2016-02-12 13:59 ` [PART1 RFC 5/9] svm: Add VMEXIT handlers for AVIC Suravee Suthikulpanit
2016-02-12 15:38 ` Paolo Bonzini
2016-02-15 19:22 ` Radim Krčmář
2016-02-16 6:29 ` Suravee Suthikulpanit
2016-02-16 12:15 ` Paolo Bonzini
2016-02-16 14:13 ` Radim Krčmář
2016-02-16 16:56 ` Paolo Bonzini
2016-02-16 18:06 ` Radim Krčmář
2016-02-18 2:25 ` Suravee Suthikulpanit
2016-02-18 14:18 ` Radim Krčmář
2016-02-18 14:51 ` Paolo Bonzini
2016-02-18 15:43 ` Radim Krčmář
2016-02-18 15:53 ` Paolo Bonzini
2016-02-18 16:27 ` Radim Krčmář
2016-02-18 17:18 ` Paolo Bonzini
2016-02-19 11:39 ` Suravee Suthikulpanit
2016-02-19 11:44 ` Paolo Bonzini
2016-02-19 11:59 ` Suravee Suthikulpanit
2016-03-03 10:42 ` Suravee Suthikulpanit
2016-03-03 10:50 ` Paolo Bonzini
2016-02-19 11:32 ` Suravee Suthikulpanit
2016-02-12 13:59 ` [PART1 RFC 6/9] svm: Add interrupt injection via AVIC Suravee Suthikulpanit
2016-02-12 14:16 ` Borislav Petkov
2016-02-12 15:54 ` Suravee Suthikulpanit
2016-02-12 17:14 ` Borislav Petkov
2016-02-12 18:21 ` Paolo Bonzini
2016-02-12 18:30 ` Borislav Petkov
2016-02-12 18:56 ` Paolo Bonzini
2016-02-12 19:33 ` Borislav Petkov
2016-02-16 7:50 ` Ingo Molnar
2016-02-16 8:39 ` [PATCH] x86/msr: Document msr-index.h rule for addition Borislav Petkov
2016-02-12 15:55 ` [PART1 RFC 6/9] svm: Add interrupt injection via AVIC Paolo Bonzini
2016-02-12 16:21 ` Suravee Suthikulpanit
2016-02-12 18:19 ` Paolo Bonzini
2016-02-12 19:36 ` Suravee Suthikulpanit
2016-02-19 11:57 ` Suravee Suthikulpanit
2016-02-12 13:59 ` [PART1 RFC 7/9] svm: Do not expose x2APIC when enable AVIC Suravee Suthikulpanit
2016-02-12 13:59 ` [PART1 RFC 8/9] svm: Do not intercept CR8 " Suravee Suthikulpanit
2016-02-12 15:48 ` Paolo Bonzini
2016-02-12 13:59 ` [PART1 RFC 9/9] svm: Manage vcpu load/unload " Suravee Suthikulpanit
2016-02-12 15:46 ` Paolo Bonzini
2016-02-12 18:13 ` Paolo Bonzini [this message]
2016-02-12 19:55 ` [PART1 RFC 0/9] KVM: x86: Introduce SVM AVIC support Suravee Suthikulpanit
2016-02-12 20:05 ` Paolo Bonzini
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