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From: Kevin Wolf <kwolf@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	agraf@suse.de, qemu-devel@nongnu.org,
	"Anthony Liguori" <anthony@codemonkey.ws>,
	"Andreas Färber" <afaerber@suse.de>
Subject: Re: [Qemu-devel] [PATCH repost] ahci: fix win7 hang on boot
Date: Tue, 29 Oct 2013 12:52:30 +0100	[thread overview]
Message-ID: <20131029115230.GB4690@dhcp-200-207.str.redhat.com> (raw)
In-Reply-To: <20131028190151.GA1994@redhat.com>

Am 28.10.2013 um 20:01 hat Michael S. Tsirkin geschrieben:
> From: Alexander Graf <agraf@suse.de>
> 
> When AHCI executes an asynchronous IDE command, it checked DRDY without
> checking either DRQ or BSY.  This sometimes caused interrupt to be sent
> before command is actually completed.
> 
> This resulted in a race condition: if guest then managed to access the
> device before command has completed, it would hang waiting for an
> interrupt.
> This was observed with windows 7 guests.
> 
> To fix, check for DRQ or BSY in additiona to DRDY, if set,
> the command is asynchronous so delay the interrupt until
> asynchronous done callback is invoked.
> 
> Reported-by: Michael S. Tsirkin <mst@redhat.com>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> Tested-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Thanks, applied to the block branch.

Kevin

  reply	other threads:[~2013-10-29 11:52 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-28 19:01 [Qemu-devel] [PATCH repost] ahci: fix win7 hang on boot Michael S. Tsirkin
2013-10-29 11:52 ` Kevin Wolf [this message]
2013-10-31 11:32 ` Paolo Bonzini
2013-10-31 11:37   ` Michael S. Tsirkin

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