linux-kernel - Re: [PATCH] kvm: x86: correctly reset dest_map->vector when restoring LAPIC state

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Message-ID: <20160919131619.GE3138@suse.de>
Date:   Mon, 19 Sep 2016 15:16:19 +0200
From:   Joerg Roedel <jroedel@...e.de>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        David Gilbert <dgilbert@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH] kvm: x86: correctly reset dest_map->vector when
 restoring LAPIC state

On Wed, Sep 14, 2016 at 11:48:32PM +0200, Paolo Bonzini wrote:
> When userspace sends KVM_SET_LAPIC, KVM schedules a check between
> the vCPU's IRR and ISR and the IOAPIC redirection table, in order
> to re-establish the IOAPIC's dest_map (the list of CPUs servicing
> the real-time clock interrupt with the corresponding vectors).
> 
> However, __rtc_irq_eoi_tracking_restore_one was forgetting to
> set dest_map->vectors.  Because of this, the IOAPIC did not process
> the real-time clock interrupt EOI, ioapic->rtc_status.pending_eoi
> got stuck at a non-zero value, and further RTC interrupts were
> reported to userspace as coalesced.
> 
> Fixes: 9e4aabe2bb3454c83dac8139cf9974503ee044db
> Fixes: 4d99ba898dd0c521ca6cdfdde55c9b58aea3cb3d
> Cc: Joerg Roedel <jroedel@...e.de>
> Cc: David Gilbert <dgilbert@...hat.com>
> Cc: Radim Krčmář <rkrcmar@...hat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>

Good catch, thanks for fixing this.