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 <kw...@redhat.com> Signed-off-by: John Snow <js...@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-v1: https://github.com/jnsnow/qemu/releases/tag/ide-reset-fix-v1 John Snow (5): ide: Prohibit RESET on IDE drives ide: code motion ide: move buffered DMA cancel to core ide: Add silent DRQ cancellation ide: fix device_reset to not ignore pending AIO hw/ide/core.c | 214 +++++++++++++++++++++++++++++++++++------------------- hw/ide/internal.h | 1 + hw/ide/pci.c | 36 +-------- 3 files changed, 143 insertions(+), 108 deletions(-) -- 2.4.3