From: Peter Xu <peterx@redhat.com>
To: Marc Zyngier <maz@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Subject: Re: [PATCH] KVM: Disable preemption in kvm_get_running_vcpu()
Date: Fri, 7 Feb 2020 12:04:43 -0500 [thread overview]
Message-ID: <20200207170443.GB720553@xz-x1> (raw)
In-Reply-To: <20200207163410.31276-1-maz@kernel.org>
On Fri, Feb 07, 2020 at 04:34:10PM +0000, Marc Zyngier wrote:
> Accessing a per-cpu variable only makes sense when preemption is
> disabled (and the kernel does check this when the right debug options
> are switched on).
>
> For kvm_get_running_vcpu(), it is fine to return the value after
> re-enabling preemption, as the preempt notifiers will make sure that
> this is kept consistent across task migration (the comment above the
> function hints at it, but lacks the crucial preemption management).
>
> While we're at it, move the comment from the ARM code, which explains
> why the whole thing works.
>
> Fixes: 7495e22bb165 ("KVM: Move running VCPU from ARM to common code").
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Reported-by: Zenghui Yu <yuzenghui@huawei.com>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> Link: https://lore.kernel.org/r/318984f6-bc36-33a3-abc6-bf2295974b06@huawei.com
Reviewed-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply other threads:[~2020-02-07 17:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-07 16:34 [PATCH] KVM: Disable preemption in kvm_get_running_vcpu() Marc Zyngier
2020-02-07 17:04 ` Peter Xu [this message]
2020-02-11 1:25 ` Zenghui Yu
2020-02-12 11:19 ` Paolo Bonzini
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=20200207170443.GB720553@xz-x1 \
--to=peterx@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=maz@kernel.org \
--cc=pbonzini@redhat.com \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).