From: Stefan Hajnoczi <stefanha@gmail.com>
To: John Snow <jsnow@redhat.com>
Cc: kwolf@redhat.com, pbonzini@redhat.com, stefanha@redhat.com,
qemu-devel@nongnu.org, qemu-block@nongnu.org
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v2 0/6] ide: fix atapi software reset
Date: Mon, 8 Feb 2016 16:10:21 +0000 [thread overview]
Message-ID: <20160208161021.GF31586@stefanha-x1.localdomain> (raw)
In-Reply-To: <1453225191-11871-1-git-send-email-jsnow@redhat.com>
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On Tue, Jan 19, 2016 at 12:39:45PM -0500, John Snow wrote:
> The ATAPI software reset function is implemented somewhat lackadaisically.
>
> Firstly, it is valid only for ATAPI drives - not HDs. If a HD should
> receive this command while BSY, it should be ignored like any other
> command instead of aborted. A non-BSY HD is free to abort the command
> in the usual fashion to indicate it doesn't understand or doesn't support
> that command.
>
> Second, for drives that should accept a software reset, they should not
> "forget" about all pending AIO during the reset. Since a software reset
> resets the DRQ and BSY flags, it is possible to 'stack' multiple
> concurrent reads using DMA and alternately chaining software reset and
> DMA reads. We mustn't reset BSY/DRQ until we are confident that we
> have canceled existing AIO.
>
> Third, the existing software reset routine does not perform a very
> rigorous reset.
>
> This series corrects this by:
>
> (1) Correcting ide_exec_cmd to correctly ignore, not abort, software
> reset commands for ide-hd devices that are busy executing a command.
>
> (2) Improving the software reset routine to cancel buffered DMA, then
> fall back to synchronously waiting for any pending DMA to finish
> before returning, insuring that the reset completes sanely.
>
> (3) Use existing reset routines to comprehensively reset the device.
>
> Reported-by: Kevin Wolf <kwolf@redhat.com>
> Signed-off-by: John Snow <jsnow@redhat.com>
>
> ________________________________________________________________________________
>
> For convenience, this branch is available at:
> https://github.com/jnsnow/qemu.git branch ide-reset-fix
> https://github.com/jnsnow/qemu/tree/ide-reset-fix
>
> This version is tagged ide-reset-fix-v2:
> https://github.com/jnsnow/qemu/releases/tag/ide-reset-fix-v2
>
> John Snow (6):
> ide: Prohibit RESET on IDE drives
> ide: code motion
> ide: move buffered DMA cancel to core
> ide: replace blk_drain_all by blk_drain
> ide: Add silent DRQ cancellation
> ide: fix device_reset to not ignore pending AIO
>
> hw/ide/core.c | 215 ++++++++++++++++++++++++++++++++++++------------------
> hw/ide/internal.h | 1 +
> hw/ide/pci.c | 36 +--------
> 3 files changed, 144 insertions(+), 108 deletions(-)
>
> --
> 2.4.3
>
>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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prev parent reply other threads:[~2016-02-08 16:10 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-19 17:39 [Qemu-devel] [PATCH v2 0/6] ide: fix atapi software reset John Snow
2016-01-19 17:39 ` [Qemu-devel] [PATCH v2 1/6] ide: Prohibit RESET on IDE drives John Snow
2016-01-19 17:39 ` [Qemu-devel] [PATCH v2 2/6] ide: code motion John Snow
2016-01-19 17:39 ` [Qemu-devel] [PATCH v2 3/6] ide: move buffered DMA cancel to core John Snow
2016-01-19 17:39 ` [Qemu-devel] [PATCH v2 4/6] ide: replace blk_drain_all by blk_drain John Snow
2016-01-19 17:39 ` [Qemu-devel] [PATCH v2 5/6] ide: Add silent DRQ cancellation John Snow
2016-02-08 16:09 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-02-08 17:08 ` John Snow
2016-02-09 13:21 ` Stefan Hajnoczi
2016-01-19 17:39 ` [Qemu-devel] [PATCH v2 6/6] ide: fix device_reset to not ignore pending AIO John Snow
2016-01-26 20:39 ` [Qemu-devel] [PATCH v2 0/6] ide: fix atapi software reset John Snow
2016-02-08 16:10 ` Stefan Hajnoczi [this message]
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