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Re: [Qemu-devel] [Qemu-block] [PATCH v2 0/6] ide: fix atapi software res
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [Qemu-block] [PATCH v2 0/6] ide: fix atapi software reset |
Date: |
Mon, 8 Feb 2016 16:10:21 +0000 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
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 <address@hidden>
> Signed-off-by: John Snow <address@hidden>
>
> ________________________________________________________________________________
>
> 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 <address@hidden>
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