Re: [Stable-7.2.6 29/37] hw/ide/ahci: PxCI should not get cleared when ERR_STAT is set

[Michael Tokarev]

09.09.2023 16:04, Michael Tokarev wrote:
> From: Niklas Cassel <niklas.cassel@wdc.com>
>
> For NCQ, PxCI is cleared on command queued successfully.
> For non-NCQ, PxCI is cleared on command completed successfully.
> Successfully means ERR_STAT, BUSY and DRQ are all cleared.
>
> A command that has ERR_STAT set, does not get to clear PxCI.
> See AHCI 1.3.1, section 5.3.8, states RegFIS:Entry and RegFIS:ClearCI,
> and 5.3.16.5 ERR:FatalTaskfile.
>
> In the case of non-NCQ commands, not clearing PxCI is needed in order
> for host software to be able to see which command slot that failed.
>
> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> Message-id: 20230609140844.202795-7-nks@flawful.org
> Signed-off-by: John Snow <jsnow@redhat.com>
> (cherry picked from commit 1a16ce64fda11bdf50f0c4ab5d9fdde72c1383a2)
> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
> Mjt: fix context in hw/ide/ahci.c for f63192b0544af5 (qemu_bh_new_guarded)

This one's interesting.  I looked at f63192b0544af5 and remember there's
this series to prevent dma/mmio reentrancy issues.  And gave it a try
on top of this 7.2 series (I already had the reentrancy fixes backported
to 7.2 in a separate branch, now added 3 more fixes in that area).  And
with these reentrancy fixes there's no need to context fixing here, it
applies cleanly right into the spot.  So I re-applied this change from
the original commit, unedited.

Dunno what to do with 8.0 version of it, - will most likely keep it with
context tweak, - although I prepared reentrancy fixes for 8.0 too.

/mjt