qemu-devel.nongnu.org archive mirror
 help / color / mirror / Atom feed
From: Peter Maydell <peter.maydell@linaro.org>
To: Salil Mehta <salil.mehta@huawei.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	Salil Mehta <salil.mehta@opnsrc.net>,
	Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH] hw/intc/arm_gicv3_kvm: Avoid reading ICC_CTLR_EL1 from kernel in cpuif reset
Date: Tue, 14 Oct 2025 16:23:40 +0100	[thread overview]
Message-ID: <CAFEAcA8GsSDnY8GEJZYNbJ3KZAp9tJ=s_vUBB_XwwGaEwozxzQ@mail.gmail.com> (raw)
In-Reply-To: <a630fc58d9f946988bd6c27479543dd1@huawei.com>

On Tue, 14 Oct 2025 at 16:13, Salil Mehta <salil.mehta@huawei.com> wrote:
>
> > From: Peter Maydell <peter.maydell@linaro.org>
> > In what situation do we ever start running a VCPU before the *GIC* has
> > been realized? The GIC should get realized as part of creating the virt board,
> > which must complete before we do anything like running a vcpu.
>
>
> Just after realization of vCPU in the machvirt_init() you can see the default
> power_state is PSCI CPU_ON, which means KVM_MP_STATE_RUNNABLE.
> Since, the thread is up and not doing IO wait in userspace it gets into
> cpu_exec() loop and actually run KVM_RUN IOCTL. Inside the KVM it
> momentarily takes the vCPU mutex but later exit and releases. This keeps
> going on for all of the vCPU threads realized early.

Yikes. We definitely should fix that : letting the vcpu run
before we get to qemu_machine_creation_done() seems like it
would be a massive source of race conditions.

-- PMM


  parent reply	other threads:[~2025-10-14 15:24 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-10-14 10:24 [PATCH] hw/intc/arm_gicv3_kvm: Avoid reading ICC_CTLR_EL1 from kernel in cpuif reset Peter Maydell
2025-10-14 10:41 ` Salil Mehta via
2025-10-14 13:23   ` Salil Mehta via
2025-10-14 13:31     ` Peter Maydell
2025-10-14 13:41       ` Salil Mehta via
2025-10-14 13:49         ` Peter Maydell
2025-10-14 14:22           ` Salil Mehta via
2025-10-14 14:28             ` Peter Maydell
2025-10-14 14:48               ` Salil Mehta via
2025-10-14 14:59                 ` Peter Maydell
2025-10-14 15:13                   ` Salil Mehta via
2025-10-14 15:16                     ` Salil Mehta via
2025-10-14 15:23                     ` Peter Maydell [this message]
2025-10-14 15:32                       ` Salil Mehta via
2025-10-14 15:43                         ` Peter Maydell
2025-10-14 15:54                           ` Salil Mehta via
2025-10-14 19:36                           ` Salil Mehta via
2025-10-17  1:43                             ` Salil Mehta
2025-10-14 16:07                         ` Salil Mehta via
2025-10-14 16:12                           ` Peter Maydell
2025-10-14 15:39                       ` Salil Mehta via
2025-10-16 12:09       ` Salil Mehta via
2025-10-15 10:58 ` Salil Mehta via
2025-10-15 12:06   ` Peter Maydell
2025-10-16 11:13     ` Salil Mehta via
2025-10-16 12:46       ` Peter Maydell
2025-10-16 15:28         ` Salil Mehta
2025-10-16 15:46           ` Peter Maydell
2025-10-16 15:48             ` Salil Mehta via
2025-10-16 12:17 ` Salil Mehta via
2025-10-16 12:22   ` Peter Maydell
2025-10-16 12:36     ` Salil Mehta

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='CAFEAcA8GsSDnY8GEJZYNbJ3KZAp9tJ=s_vUBB_XwwGaEwozxzQ@mail.gmail.com' \
    --to=peter.maydell@linaro.org \
    --cc=maz@kernel.org \
    --cc=qemu-devel@nongnu.org \
    --cc=salil.mehta@huawei.com \
    --cc=salil.mehta@opnsrc.net \
    /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).