From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Joel Fernandes <joelaf@google.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Suleiman Souhlal <suleiman@google.com>,
Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCHv2 4/4] arm64: add host pv-vcpu-state support
Date: Wed, 21 Jul 2021 19:38:40 +0900 [thread overview]
Message-ID: <YPf5MFV99zPdTu/U@google.com> (raw)
In-Reply-To: <87h7go2h69.wl-maz@kernel.org>
On (21/07/21 09:40), Marc Zyngier wrote:
> >
> > Can that be cured by just checking vcpu->preempted before calling
> > kvm_update_vcpu_preempted() ?
>
> It isn't obvious to me that this is the right thing to do.
> vcpu->preempted is always updated on sched-out from the preempt
> notifier if the vcpu was on the run-queue, so my guess is that it will
> always be set when switching to another task.
>
> What you probably want is to check whether the vcpu is blocked by
> introspecting the wait-queue with:
>
> scuwait_active(kvm_arch_vcpu_get_wait(vcpu)
>
> which will tell you whether you are blocking or not. We are already
> using a similar construct for arming a background timer in this case.
Can we examine if vcpu->run->exit_reason == WFE/WFI and avoid setting
preempted state if so?
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Joel Fernandes <joelaf@google.com>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Will Deacon <will@kernel.org>,
Suleiman Souhlal <suleiman@google.com>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCHv2 4/4] arm64: add host pv-vcpu-state support
Date: Wed, 21 Jul 2021 19:38:40 +0900 [thread overview]
Message-ID: <YPf5MFV99zPdTu/U@google.com> (raw)
In-Reply-To: <87h7go2h69.wl-maz@kernel.org>
On (21/07/21 09:40), Marc Zyngier wrote:
> >
> > Can that be cured by just checking vcpu->preempted before calling
> > kvm_update_vcpu_preempted() ?
>
> It isn't obvious to me that this is the right thing to do.
> vcpu->preempted is always updated on sched-out from the preempt
> notifier if the vcpu was on the run-queue, so my guess is that it will
> always be set when switching to another task.
>
> What you probably want is to check whether the vcpu is blocked by
> introspecting the wait-queue with:
>
> scuwait_active(kvm_arch_vcpu_get_wait(vcpu)
>
> which will tell you whether you are blocking or not. We are already
> using a similar construct for arming a background timer in this case.
Can we examine if vcpu->run->exit_reason == WFE/WFI and avoid setting
preempted state if so?
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Joel Fernandes <joelaf@google.com>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Will Deacon <will@kernel.org>,
Suleiman Souhlal <suleiman@google.com>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCHv2 4/4] arm64: add host pv-vcpu-state support
Date: Wed, 21 Jul 2021 19:38:40 +0900 [thread overview]
Message-ID: <YPf5MFV99zPdTu/U@google.com> (raw)
In-Reply-To: <87h7go2h69.wl-maz@kernel.org>
On (21/07/21 09:40), Marc Zyngier wrote:
> >
> > Can that be cured by just checking vcpu->preempted before calling
> > kvm_update_vcpu_preempted() ?
>
> It isn't obvious to me that this is the right thing to do.
> vcpu->preempted is always updated on sched-out from the preempt
> notifier if the vcpu was on the run-queue, so my guess is that it will
> always be set when switching to another task.
>
> What you probably want is to check whether the vcpu is blocked by
> introspecting the wait-queue with:
>
> scuwait_active(kvm_arch_vcpu_get_wait(vcpu)
>
> which will tell you whether you are blocking or not. We are already
> using a similar construct for arming a background timer in this case.
Can we examine if vcpu->run->exit_reason == WFE/WFI and avoid setting
preempted state if so?
next prev parent reply other threads:[~2021-07-21 12:20 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-09 4:37 [PATCHv2 0/4] arm64:kvm: teach guest sched that VCPUs can be preempted Sergey Senozhatsky
2021-07-09 4:37 ` Sergey Senozhatsky
2021-07-09 4:37 ` Sergey Senozhatsky
2021-07-09 4:37 ` [PATCHv2 1/4] arm64: smccc: Add SMCCC pv-vcpu-state function call IDs Sergey Senozhatsky
2021-07-09 4:37 ` Sergey Senozhatsky
2021-07-09 4:37 ` Sergey Senozhatsky
2021-07-12 14:22 ` Marc Zyngier
2021-07-12 14:22 ` Marc Zyngier
2021-07-12 14:22 ` Marc Zyngier
2021-07-09 4:37 ` [PATCHv2 2/4] arm64: add guest pvstate support Sergey Senozhatsky
2021-07-09 4:37 ` Sergey Senozhatsky
2021-07-09 4:37 ` Sergey Senozhatsky
2021-07-09 7:39 ` David Edmondson
2021-07-09 7:39 ` David Edmondson
2021-07-09 7:39 ` David Edmondson
2021-07-09 7:52 ` Sergey Senozhatsky
2021-07-09 7:52 ` Sergey Senozhatsky
2021-07-09 7:52 ` Sergey Senozhatsky
2021-07-09 18:58 ` Joel Fernandes
2021-07-09 18:58 ` Joel Fernandes
2021-07-09 18:58 ` Joel Fernandes
2021-07-09 21:53 ` Sergey Senozhatsky
2021-07-09 21:53 ` Sergey Senozhatsky
2021-07-09 21:53 ` Sergey Senozhatsky
2021-07-11 16:58 ` Joel Fernandes
2021-07-11 16:58 ` Joel Fernandes
2021-07-11 16:58 ` Joel Fernandes
2021-07-12 15:42 ` Marc Zyngier
2021-07-12 15:42 ` Marc Zyngier
2021-07-12 15:42 ` Marc Zyngier
2021-07-21 2:05 ` Sergey Senozhatsky
2021-07-21 2:05 ` Sergey Senozhatsky
2021-07-21 2:05 ` Sergey Senozhatsky
2021-07-21 8:22 ` Marc Zyngier
2021-07-21 8:22 ` Marc Zyngier
2021-07-21 8:22 ` Marc Zyngier
2021-07-21 8:47 ` Sergey Senozhatsky
2021-07-21 8:47 ` Sergey Senozhatsky
2021-07-21 8:47 ` Sergey Senozhatsky
2021-07-21 10:16 ` Marc Zyngier
2021-07-21 10:16 ` Marc Zyngier
2021-07-21 10:16 ` Marc Zyngier
2021-07-09 4:37 ` [PATCHv2 3/4] arm64: do not use dummy vcpu_is_preempted() Sergey Senozhatsky
2021-07-09 4:37 ` Sergey Senozhatsky
2021-07-09 4:37 ` Sergey Senozhatsky
2021-07-12 15:47 ` Marc Zyngier
2021-07-12 15:47 ` Marc Zyngier
2021-07-12 15:47 ` Marc Zyngier
2021-07-21 2:06 ` Sergey Senozhatsky
2021-07-21 2:06 ` Sergey Senozhatsky
2021-07-21 2:06 ` Sergey Senozhatsky
2021-07-09 4:37 ` [PATCHv2 4/4] arm64: add host pv-vcpu-state support Sergey Senozhatsky
2021-07-09 4:37 ` Sergey Senozhatsky
2021-07-09 4:37 ` Sergey Senozhatsky
2021-07-12 16:24 ` Marc Zyngier
2021-07-12 16:24 ` Marc Zyngier
2021-07-12 16:24 ` Marc Zyngier
2021-07-20 18:44 ` Joel Fernandes
2021-07-20 18:44 ` Joel Fernandes
2021-07-20 18:44 ` Joel Fernandes
2021-07-21 8:40 ` Marc Zyngier
2021-07-21 8:40 ` Marc Zyngier
2021-07-21 8:40 ` Marc Zyngier
2021-07-21 10:38 ` Sergey Senozhatsky [this message]
2021-07-21 10:38 ` Sergey Senozhatsky
2021-07-21 10:38 ` Sergey Senozhatsky
2021-07-21 11:08 ` Marc Zyngier
2021-07-21 11:08 ` Marc Zyngier
2021-07-21 11:08 ` Marc Zyngier
2021-07-21 1:15 ` Sergey Senozhatsky
2021-07-21 1:15 ` Sergey Senozhatsky
2021-07-21 1:15 ` Sergey Senozhatsky
2021-07-21 9:10 ` Marc Zyngier
2021-07-21 9:10 ` Marc Zyngier
2021-07-21 9:10 ` Marc Zyngier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YPf5MFV99zPdTu/U@google.com \
--to=senozhatsky@chromium.org \
--cc=joelaf@google.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maz@kernel.org \
--cc=suleiman@google.com \
--cc=virtualization@lists.linux-foundation.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.