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

[Niklas Cassel]

On Mon, Sep 11, 2023 at 12:07:52AM +0300, Michael Tokarev wrote:
> 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.

Nice!

Not needing to modify patches when backporting will reducing the chance
that we will need to spend time on conflicts (because of modifications)
in the future.


Kind regards,
Niklas