From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
Coleman Dietsch <dietschc@csp.edu>,
kvm@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org, skhan@linuxfoundation.org,
Pavel Skripkin <paskripkin@gmail.com>,
linux-kernel-mentees@lists.linuxfoundation.org,
stable@vger.kernel.org,
syzbot+e54f930ed78eb0f85281@syzkaller.appspotmail.com,
metikaya <metikaya@amazon.co.uk>
Subject: Re: [PATCH v3 2/2] KVM: x86/xen: Stop Xen timer before changing IRQ
Date: Tue, 9 Aug 2022 14:40:28 +0000 [thread overview]
Message-ID: <YvJx3Dje4zS/c+H0@google.com> (raw)
In-Reply-To: <953d2e99-ed1a-384d-6d3a-0f656a243f82@redhat.com>
On Tue, Aug 09, 2022, Paolo Bonzini wrote:
> On 8/9/22 16:16, David Woodhouse wrote:
> > I find the new version a bit harder to follow, with its init-then-stop-
> > then-start logic:
> >
> > case KVM_XEN_VCPU_ATTR_TYPE_TIMER:
> > if (data->u.timer.port &&
> > data->u.timer.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL) {
> > r = -EINVAL;
> > break;
> > }
> >
> > if (!vcpu->arch.xen.timer.function)
> > kvm_xen_init_timer(vcpu);
> >
> > /* Stop the timer (if it's running) before changing the vector */
> > kvm_xen_stop_timer(vcpu);
> > vcpu->arch.xen.timer_virq = data->u.timer.port;
>
>
> I think this is fine, if anything the kvm_xen_stop_timer() call could be
> placed in an "else" but I'm leaning towards applying this version of the
> patch.
I wanted to separate the "init" from the "stop+start", e.g. if there were a more
appropriate place for invoking kvm_xen_init_timer() I would have suggested moving
the call outside of KVM_XEN_VCPU_ATTR_TYPE_TIMER entirely.
next prev parent reply other threads:[~2022-08-09 14:40 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-08 19:06 [PATCH v3 1/2] KVM: x86/xen: Initialize Xen timer only once Coleman Dietsch
2022-08-08 19:06 ` [PATCH v3 2/2] KVM: x86/xen: Stop Xen timer before changing IRQ Coleman Dietsch
2022-08-09 0:34 ` Sean Christopherson
2022-08-09 9:22 ` David Woodhouse
2022-08-09 12:59 ` Paolo Bonzini
2022-08-09 13:51 ` David Woodhouse
2022-08-09 14:07 ` Sean Christopherson
2022-08-09 14:16 ` David Woodhouse
2022-08-09 14:31 ` Paolo Bonzini
2022-08-09 14:36 ` David Woodhouse
2022-08-09 14:40 ` Sean Christopherson [this message]
2022-08-09 14:52 ` David Woodhouse
2022-08-09 0:32 ` [PATCH v3 1/2] KVM: x86/xen: Initialize Xen timer only once Sean Christopherson
2022-08-09 12:59 ` Paolo Bonzini
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