From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
yang zhang wz <yang.zhang.wz@gmail.com>,
feng wu <feng.wu@intel.com>,
mst@redhat.com
Subject: Re: [RFC PATCH 0/3] kvm: x86: speedups for APICv
Date: Fri, 30 Sep 2016 15:23:04 +0200 [thread overview]
Message-ID: <20160930132304.GF13257@potion> (raw)
In-Reply-To: <1865155490.553427.1475185306049.JavaMail.zimbra@redhat.com>
2016-09-29 17:41-0400, Paolo Bonzini:
>> Another possible optimization: when delivering an IPI, don't write the
>> vector to PIR, but directly to VIRR. If the guest is not in VMX
>> non-root mode, then vm entry will take care of the injection; in the
>> other case, we'll send POSTED_INTR_VECTOR.
>> It seems that we don't even have to set PI.ON -- SDM doesn't say it is
>> necessary to evaluate pending virtual interrupts after receiving the
>> notification interrupt. If we have to set PI.ON, we can just skip the
>> PIR->VIRR sync as long as the VM doesn't have an assigned device,
>> because we know that PIR is empty.
>
> Nope, you cannot write to the APIC page while the VM is running.
True, thanks.
> (We're already reading the manual in such a way as to "allow" us to
> write TMR while the VM is running, but that should not be extended.
> For example the SDM doesn't say that the processor accesses VIRR with
> atomic instructions, in fact it probably doesn't).
Yeah, TMR is not used by the hardware ...
next prev parent reply other threads:[~2016-09-30 13:23 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-27 21:20 [RFC PATCH 0/3] kvm: x86: speedups for APICv Paolo Bonzini
2016-09-27 21:20 ` [PATCH 1/3] kvm: x86: avoid atomic operations on APICv vmentry Paolo Bonzini
2016-09-27 21:20 ` [PATCH 2/3] kvm: x86: do not use KVM_REQ_EVENT for APICv interrupt injection Paolo Bonzini
2016-09-27 23:07 ` Michael S. Tsirkin
2016-09-28 8:21 ` Paolo Bonzini
2016-09-28 11:40 ` Wu, Feng
2016-09-28 11:50 ` Paolo Bonzini
2016-09-28 12:06 ` Wu, Feng
2016-09-28 12:14 ` Paolo Bonzini
2016-10-14 7:37 ` Yang Zhang
2016-10-14 8:12 ` Paolo Bonzini
2016-09-28 13:46 ` Michael S. Tsirkin
2016-09-28 14:08 ` Paolo Bonzini
2016-09-28 10:04 ` Wu, Feng
2016-09-28 10:16 ` Paolo Bonzini
2016-09-28 11:53 ` Wu, Feng
2016-09-28 11:55 ` Paolo Bonzini
2016-09-28 12:07 ` Wu, Feng
2016-10-14 7:12 ` Yang Zhang
2016-09-27 21:20 ` [PATCH 3/3] KVM: x86: do not scan IRR twice on APICv vmentry Paolo Bonzini
2016-09-28 14:00 ` Michael S. Tsirkin
2016-09-28 14:44 ` Paolo Bonzini
2016-09-29 2:51 ` Wu, Feng
2016-10-14 7:32 ` Yang Zhang
2016-10-14 7:45 ` Paolo Bonzini
2016-09-29 19:55 ` [RFC PATCH 0/3] kvm: x86: speedups for APICv Radim Krčmář
2016-09-29 21:41 ` Paolo Bonzini
2016-09-30 13:23 ` Radim Krčmář [this message]
2016-09-30 13:33 ` Radim Krčmář
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