From: Paolo Bonzini <pbonzini@redhat.com>
To: "Zhang, Yang Z" <yang.z.zhang@intel.com>,
"Wang, Wei W" <wei.w.wang@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Cc: "alex.williamson@redhat.com" <alex.williamson@redhat.com>
Subject: Re: [PATCH v2] KVM: x86: keep eoi exit bitmap accurate before loading it.
Date: Thu, 28 Aug 2014 10:44:04 +0200 [thread overview]
Message-ID: <53FEEBD4.8030202@redhat.com> (raw)
In-Reply-To: <A9667DDFB95DB7438FA9D7D576C3D87E0AB6FEA1@SHSMSX104.ccr.corp.intel.com>
Il 28/08/2014 08:17, Zhang, Yang Z ha scritto:
> > Program edge-triggered MSI for vector 123
> > Interrupt comes in, ISR[123]=1
> > Mask MSI
> > Program level-triggered IOAPIC interrupt for vector 123
>
> You cannot assign the vector 123 to another trigger mode interrupt
> before previous IRQ handler finished (means issue EOI). If there is an
> interrupt comes from the IOAPIC entry immediately after you reprogram
> the entry, it will update the TMR to 1. Since we are still in previous
> IRQ handler, it will get confused to see the TMR becomes 1.
Yeah, that could be confusing to real hardware as well. Still, I'm a
bit nervous at the possibility of races introduced by these patches...
I wouldn't mind a second review.
Paolo
next prev parent reply other threads:[~2014-08-28 8:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-27 14:05 [PATCH v2] KVM: x86: keep eoi exit bitmap accurate before loading it Wei Wang
2014-08-27 14:27 ` Paolo Bonzini
2014-08-28 6:17 ` Zhang, Yang Z
2014-08-28 8:44 ` Paolo Bonzini [this message]
2014-08-28 10:14 ` Wang, Wei W
2014-08-28 11:00 ` Paolo Bonzini
2014-08-29 0:59 ` Wang, Wei W
2014-09-04 2:23 ` Wang, Wei W
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