From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43150) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vas2X-0004T4-94 for qemu-devel@nongnu.org; Mon, 28 Oct 2013 14:59:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Vas2S-0001f7-Dt for qemu-devel@nongnu.org; Mon, 28 Oct 2013 14:59:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:62073) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vas2S-0001f0-4o for qemu-devel@nongnu.org; Mon, 28 Oct 2013 14:59:44 -0400 Date: Mon, 28 Oct 2013 21:02:26 +0200 From: "Michael S. Tsirkin" Message-ID: <20131028190226.GA1997@redhat.com> References: <20131028190015.GA1923@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131028190015.GA1923@redhat.com> Subject: Re: [Qemu-devel] [PATCH] ahci fix: windows boots fine. need to review with kwolf List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Paolo Bonzini , Andreas =?iso-8859-1?Q?F=E4rber?= , Anthony Liguori , agraf@suse.de On Mon, Oct 28, 2013 at 09:00:15PM +0200, Michael S. Tsirkin wrote: > From: Alexander Graf > > 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 > Reviewed-by: Michael S. Tsirkin > Tested-by: Michael S. Tsirkin > Signed-off-by: Michael S. Tsirkin Sorry about the subject, forgot to update it. I reposted with a fixed subject. > --- > hw/ide/ahci.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c > index a8be62c..fbea9e8 100644 > --- a/hw/ide/ahci.c > +++ b/hw/ide/ahci.c > @@ -961,7 +961,8 @@ static int handle_cmd(AHCIState *s, int port, int slot) > /* We're ready to process the command in FIS byte 2. */ > ide_exec_cmd(&s->dev[port].port, cmd_fis[2]); > > - if (s->dev[port].port.ifs[0].status & READY_STAT) { > + if ((s->dev[port].port.ifs[0].status & (READY_STAT|DRQ_STAT|BUSY_STAT)) == > + READY_STAT) { > ahci_write_fis_d2h(&s->dev[port], cmd_fis); > } > } > -- > MST