Re: [Qemu-devel] [PATCH_v2] ahci.c: mask unused flags when reading size PRDT DBC

[John Snow <jsnow@redhat.com>]

On 07/01/2014 07:36 AM, Kevin Wolf wrote:
> Am 01.07.2014 um 13:13 hat reza.jelveh@tuhh.de geschrieben:
>> From: Reza Jelveh <reza.jelveh@tuhh.de>
>>
>> The data byte count(DBC) read from the description information is defined for
>> bits 21:00. Bits 30:22 are reserved and bit 31 is the Interrupt on Completion
>> (I) flag.
>>
>> Completion interrupts are triggered after every transaction instead of on
>> I-flag in QEMU. tbl_entry_size is a signed integer and improperly reading the
>> DBC leads to a negative offset that causes sglist allocation to fail.
>>
>> Signed-off-by: Reza Jelveh <reza.jelveh@tuhh.de>
>> ---
>> This requires a custom ovmf image with sata controller for testing:
>>
>> http://reza.jelveh.me/assets/OVMF.fd.bz2
>>
>> Signed-off-by: Reza Jelveh <reza.jelveh@tuhh.de>
> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
>
> The spec also seems to require an even byte count, which we don't seem
> to check. Do we want to add this? (In a separate patch, of course.)
>
> We'll also want a qtest case to verify the fix and for regression
> testing. John?
>
> And finally, please don't forget to CC the block maintainers (Stefan and
> me) for any AHCI patches.
>
> Kevin
>
The test_identify case I submitted a patch for ( 
http://lists.gnu.org/archive/html/qemu-devel/2014-07/msg01241.html ) 
does attempt to use the interrupt bit, and as such, will fail without 
Reza's patch.

The current version of the test only warns when it doesn't see the 
interrupt posted, though, but that's not relevant to testing this 
particular fix.

--John