Re: [PATCH v3 1/2] ide: Fix incorrect handling of some PRDTs in ide_dma_cb()

[Kevin Wolf <kwolf@redhat.com>]

Am 23.12.2019 um 18:51 hat Alexander Popov geschrieben:
> The commit a718978ed58a from July 2015 introduced the assertion which
> implies that the size of successful DMA transfers handled in ide_dma_cb()
> should be multiple of 512 (the size of a sector). But guest systems can
> initiate DMA transfers that don't fit this requirement.
> 
> For fixing that let's check the number of bytes prepared for the transfer
> by the prepare_buf() handler. The code in ide_dma_cb() must behave
> according to the Programming Interface for Bus Master IDE Controller
> (Revision 1.0 5/16/94):
> 1. If PRDs specified a smaller size than the IDE transfer
>    size, then the Interrupt and Active bits in the Controller
>    status register are not set (Error Condition).
> 2. If the size of the physical memory regions was equal to
>    the IDE device transfer size, the Interrupt bit in the
>    Controller status register is set to 1, Active bit is set to 0.
> 3. If PRDs specified a larger size than the IDE transfer size,
>    the Interrupt and Active bits in the Controller status register
>    are both set to 1.
> 
> Signed-off-by: Alexander Popov <alex.popov@linux.com>

Reviewed-by: Kevin Wolf <kwolf@redhat.com>