From: Wanpeng Li <kernellwp@gmail.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
w90p710@gmail.com, Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] Revert "KVM: x86: Unconditionally enable irqs in guest context"
Date: Tue, 19 Jan 2021 09:27:13 +0800 [thread overview]
Message-ID: <CANRm+CwCqnNWr3KELG=6DLkOdWMnMP3uuyyROgXpZrPyo2A+bA@mail.gmail.com> (raw)
In-Reply-To: <CANRm+Cz1nHkLm=hg-JN3j-s-w1_c0zWm=EYLJ7hzPW-2k_a2Gw@mail.gmail.com>
On Fri, 15 Jan 2021 at 11:20, Wanpeng Li <kernellwp@gmail.com> wrote:
>
> On Wed, 6 Jan 2021 at 08:51, Sean Christopherson <seanjc@google.com> wrote:
> >
> > +tglx
> >
> > On Tue, Jan 05, 2021, Nitesh Narayan Lal wrote:
> > > This reverts commit d7a08882a0a4b4e176691331ee3f492996579534.
> > >
> > > After the introduction of the patch:
> > >
> > > 87fa7f3e9: x86/kvm: Move context tracking where it belongs
> > >
> > > since we have moved guest_exit_irqoff closer to the VM-Exit, explicit
> > > enabling of irqs to process pending interrupts should not be required
> > > within vcpu_enter_guest anymore.
> >
> > Ugh, except that commit completely broke tick-based accounting, on both Intel
> > and AMD. With guest_exit_irqoff() being called immediately after VM-Exit, any
> > tick that happens after IRQs are disabled will be accounted to the host. E.g.
> > on Intel, even an IRQ VM-Exit that has already been acked by the CPU isn't
> > processed until kvm_x86_ops.handle_exit_irqoff(), well after PF_VCPU has been
> > cleared.
> >
>
> This issue can be 100% reproduced.
> https://bugzilla.kernel.org/show_bug.cgi?id=204177
Sorry, the posted link should be
https://bugzilla.kernel.org/show_bug.cgi?id=209831
Wanpeng
next prev parent reply other threads:[~2021-01-19 1:28 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-05 19:28 [PATCH] Revert "KVM: x86: Unconditionally enable irqs in guest context" Nitesh Narayan Lal
2021-01-06 0:42 ` Wanpeng Li
2021-01-06 0:47 ` Sean Christopherson
2021-01-06 1:35 ` Nitesh Narayan Lal
2021-01-15 3:20 ` Wanpeng Li
2021-01-19 1:27 ` Wanpeng Li [this message]
2021-01-06 10:09 ` Vitaly Kuznetsov
2021-01-06 17:11 ` Sean Christopherson
2021-01-07 9:33 ` Vitaly Kuznetsov
2021-01-07 9:41 ` Wanpeng Li
2021-01-12 21:43 ` Nitesh Narayan Lal
2021-01-12 22:04 ` Sean Christopherson
2021-01-07 10:55 ` Xinlong Lin
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