[PATCH 8/9] hw/ide/ahci: fix ahci_write_fis_sdb()

From: Niklas Cassel <nks@flawful.org>
To: John Snow <jsnow@redhat.com>
Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org,
	Damien Le Moal <dlemoal@kernel.org>,
	Niklas Cassel <niklas.cassel@wdc.com>
Subject: [PATCH 8/9] hw/ide/ahci: fix ahci_write_fis_sdb()
Date: Fri, 28 Apr 2023 15:21:23 +0200	[thread overview]
Message-ID: <20230428132124.670840-9-nks@flawful.org> (raw)
In-Reply-To: <20230428132124.670840-1-nks@flawful.org>

From: Niklas Cassel <niklas.cassel@wdc.com>

When there is an error, we need to raise a TFES error irq, see AHCI 1.3.1,
5.3.13.1 SDB:Entry.

If ERR_STAT is set, we jump to state ERR:FatalTaskfile, which will raise
a TFES IRQ unconditionally, regardless if the I bit is set in the FIS or
not.

Thus, we should never raise a normal IRQ after having sent an error IRQ.

It is valid to signal successfully completed commands as finished in the
same SDB FIS that generates the error IRQ. The important thing is that
commands that did not complete successfully (e.g. commands that were
aborted, do not get the finished bit set).

Before this commit, there was never a TFES IRQ raised on NCQ error.

Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
---
 hw/ide/ahci.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
index d88961b4c0..4950d3575e 100644
--- a/hw/ide/ahci.c
+++ b/hw/ide/ahci.c
@@ -806,8 +806,14 @@ static void ahci_write_fis_sdb(AHCIState *s, NCQTransferState *ncq_tfs)
     pr->scr_act &= ~ad->finished;
     ad->finished = 0;
 
-    /* Trigger IRQ if interrupt bit is set (which currently, it always is) */
-    if (sdb_fis->flags & 0x40) {
+    /*
+     * TFES IRQ is always raised if ERR_STAT is set, regardless of I bit.
+     * If ERR_STAT is not set, trigger SDBS IRQ if interrupt bit is set
+     * (which currently, it always is).
+     */
+    if (sdb_fis->status & ERR_STAT) {
+        ahci_trigger_irq(s, ad, AHCI_PORT_IRQ_BIT_TFES);
+    } else if (sdb_fis->flags & 0x40) {
         ahci_trigger_irq(s, ad, AHCI_PORT_IRQ_BIT_SDBS);
     }
 }
-- 
2.40.0


