[Qemu-devel] [PATCH 1/5] ahci: add is_ncq predicate helper

[John Snow <jsnow@redhat.com>]

A small helper to determine which S/ATA commands
are destined to be routed to the NCQ pathways.

This references SATA 3.2 section 13.6,
Native Command Queueing. See sections 13.6.4,
13.6.5, 13.6.6, 13.6.7 and 13.6.8 for all
SATA commands considered to be part of the
NCQ feature set. This is summarized in a small
list in section 13.6.3.1 and again in 13.6.3.2.

Not all of these NCQ commands are currently supported,
so the error pathways are adjusted slightly to be more
informative in the case they are encountered.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 hw/ide/ahci.c | 28 ++++++++++++++++++++++++----
 hw/ide/ahci.h |  3 +++
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
index f49be9f..722ac4a 100644
--- a/hw/ide/ahci.c
+++ b/hw/ide/ahci.c
@@ -854,6 +854,21 @@ static void ncq_cb(void *opaque, int ret)
     ncq_tfs->used = 0;
 }
 
+static int is_ncq(uint8_t ata_cmd)
+{
+    /* Based on SATA 3.2 section 13.6.3.2 */
+    switch (ata_cmd) {
+    case READ_FPDMA_QUEUED:
+    case WRITE_FPDMA_QUEUED:
+    case NCQ_NON_DATA:
+    case RECEIVE_FPDMA_QUEUED:
+    case SEND_FPDMA_QUEUED:
+        return 1;
+    default:
+        return 0;
+    }
+}
+
 static void process_ncq_command(AHCIState *s, int port, uint8_t *cmd_fis,
                                 int slot)
 {
@@ -919,9 +934,15 @@ static void process_ncq_command(AHCIState *s, int port, uint8_t *cmd_fis,
                                            ncq_cb, ncq_tfs);
             break;
         default:
-            DPRINTF(port, "error: tried to process non-NCQ command as NCQ\n");
+            if (is_ncq(cmd_fis[2])) {
+                DPRINTF(port,
+                        "error: unsupported NCQ command (0x%02x) received\n",
+                        cmd_fis[2]);
+            } else {
+                DPRINTF(port,
+                        "error: tried to process non-NCQ command as NCQ\n");
+            }
             qemu_sglist_destroy(&ncq_tfs->sglist);
-            break;
     }
 }
 
@@ -1013,8 +1034,7 @@ static int handle_cmd(AHCIState *s, int port, int slot)
     if (cmd_fis[1] == SATA_FIS_REG_H2D_UPDATE_COMMAND_REGISTER) {
 
         /* Check for NCQ command */
-        if ((cmd_fis[2] == READ_FPDMA_QUEUED) ||
-            (cmd_fis[2] == WRITE_FPDMA_QUEUED)) {
+        if (is_ncq(cmd_fis[2])) {
             process_ncq_command(s, port, cmd_fis, slot);
             goto out;
         }
diff --git a/hw/ide/ahci.h b/hw/ide/ahci.h
index b123237..e0d2eb8 100644
--- a/hw/ide/ahci.h
+++ b/hw/ide/ahci.h
@@ -186,6 +186,9 @@
 
 #define READ_FPDMA_QUEUED                  0x60
 #define WRITE_FPDMA_QUEUED                 0x61
+#define NCQ_NON_DATA                       0x63
+#define RECEIVE_FPDMA_QUEUED               0x65
+#define SEND_FPDMA_QUEUED                  0x64
 
 #define RES_FIS_DSFIS                      0x00
 #define RES_FIS_PSFIS                      0x20
-- 
1.9.3