From: Oliver Upton <oliver.upton@linux.dev>
To: Will Deacon <will@kernel.org>
Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org,
Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Salil Mehta <salil.mehta@huawei.com>
Subject: Re: [PATCH kvmtool v3 08/17] Add helpers to pause the VM from vCPU thread
Date: Mon, 18 Sep 2023 10:05:36 -0700 [thread overview]
Message-ID: <ZQiDYLgicCnXA5a0@linux.dev> (raw)
In-Reply-To: <20230918104028.GA17744@willie-the-truck>
Hey Will,
On Mon, Sep 18, 2023 at 11:40:28AM +0100, Will Deacon wrote:
> On Wed, Aug 02, 2023 at 11:42:46PM +0000, Oliver Upton wrote:
> > +void kvm_cpu__pause_vm(struct kvm_cpu *vcpu)
> > +{
> > + /*
> > + * Mark the calling vCPU as paused to avoid waiting indefinitely for a
> > + * signal exit.
> > + */
> > + vcpu->paused = true;
> > + kvm__pause(vcpu->kvm);
> > +}
> > +
> > +void kvm_cpu__continue_vm(struct kvm_cpu *vcpu)
> > +{
> > + vcpu->paused = false;
> > + kvm__continue(vcpu->kvm);
> > +}
>
> Why is it safe to manipulate 'vcpu->paused' here without the pause_lock
> held?
Heh, I hacked this up to get _something_ working and never re-evaluated
the locking that I completely sidestepped.
> Relatedly, how does this interact with the 'pause' and 'resume'
> lkvm commands?
Poorly, if I had to guess. I hadn't actually tested with them. I'll take
another crack at this to safely quiesce when handling calls.
Thanks for having a look.
--
Best,
Oliver
next prev parent reply other threads:[~2023-09-18 17:05 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-02 23:42 [PATCH kvmtool v3 00/17] aarch64: Handle PSCI calls in userspace Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 01/17] Import arm-smccc.h from Linux 6.5-rc1 Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 02/17] aarch64: Copy cputype.h " Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 03/17] Update psci.h to " Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 04/17] arm: Stash kvm_vcpu_init for later use Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 05/17] arm: Use KVM_SET_MP_STATE ioctl to power off non-boot vCPUs Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 06/17] aarch64: Expose ARM64_CORE_REG() for general use Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 07/17] arm: Generalize execution state specific VM initialization Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 08/17] Add helpers to pause the VM from vCPU thread Oliver Upton
2023-09-18 10:40 ` Will Deacon
2023-09-18 17:05 ` Oliver Upton [this message]
2023-08-02 23:42 ` [PATCH kvmtool v3 09/17] aarch64: Add support for finding vCPU for given MPIDR Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 10/17] aarch64: Add skeleton implementation for PSCI Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 11/17] aarch64: psci: Implement CPU_SUSPEND Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 12/17] aarch64: psci: Implement CPU_OFF Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 13/17] aarch64: psci: Implement CPU_ON Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 14/17] aarch64: psci: Implement AFFINITY_INFO Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 15/17] aarch64: psci: Implement MIGRATE_INFO_TYPE Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 16/17] aarch64: psci: Implement SYSTEM_{OFF,RESET} Oliver Upton
2023-08-02 23:42 ` [PATCH kvmtool v3 17/17] aarch64: smccc: Start sending PSCI to userspace Oliver Upton
2023-09-13 18:42 ` [PATCH kvmtool v3 00/17] aarch64: Handle PSCI calls in userspace Oliver Upton
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