[Qemu-block] [PATCH 13/16] ahci: add get_cmd_header helper

[John Snow]

cur_cmd is an internal bookmark that points to the
current AHCI Command Header being processed by the
AHCI state machine. With NCQ needing to occasionally
rely on some of the same AHCI helpers, we cannot use
cur_cmd and will need to grab explicit pointers instead.

In an attempt to begin relying on the cur_cmd pointer
less, add a helper to let us specifically get the pointer
to the command header of particular interest.

Signed-off-by: John Snow <address@hidden>
---
 hw/ide/ahci.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
index a29cf49..eeb48fb 100644
--- a/hw/ide/ahci.c
+++ b/hw/ide/ahci.c
@@ -1115,11 +1115,20 @@ static void process_ncq_command(AHCIState *s, int port, 
uint8_t *cmd_fis,
     execute_ncq_command(ncq_tfs);
 }
 
+static AHCICmdHdr *get_cmd_header(AHCIState *s, uint8_t port, uint8_t slot)
+{
+    if (port > s->ports || slot > AHCI_MAX_CMDS) {
+        return NULL;
+    }
+
+    return s->dev[port].lst ? &((AHCICmdHdr *)s->dev[port].lst)[slot] : NULL;
+}
+
 static void handle_reg_h2d_fis(AHCIState *s, int port,
                                uint8_t slot, uint8_t *cmd_fis)
 {
     IDEState *ide_state = &s->dev[port].port.ifs[0];
-    AHCICmdHdr *cmd = s->dev[port].cur_cmd;
+    AHCICmdHdr *cmd = get_cmd_header(s, port, slot);
     uint16_t opts = le16_to_cpu(cmd->opts);
 
     if (cmd_fis[1] & 0x0F) {
@@ -1218,7 +1227,7 @@ static int handle_cmd(AHCIState *s, int port, uint8_t 
slot)
         DPRINTF(port, "error: lst not given but cmd handled");
         return -1;
     }
-    cmd = &((AHCICmdHdr *)s->dev[port].lst)[slot];
+    cmd = get_cmd_header(s, port, slot);
     /* remember current slot handle for later */
     s->dev[port].cur_cmd = cmd;
 
@@ -1592,7 +1601,7 @@ static int ahci_state_post_load(void *opaque, int 
version_id)
             if (ncq_tfs->slot > AHCI_MAX_CMDS) {
                 return -1;
             }
-            ncq_tfs->cmdh = &((AHCICmdHdr *)ad->lst)[ncq_tfs->slot];
+            ncq_tfs->cmdh = get_cmd_header(s, i, ncq_tfs->slot);
             ahci_populate_sglist(ncq_tfs->drive, &ncq_tfs->sglist,
                                  ncq_tfs->cmdh, ncq_tfs->sector_count * 512,
                                  0);
@@ -1618,7 +1627,7 @@ static int ahci_state_post_load(void *opaque, int 
version_id)
             if (ad->busy_slot < 0 || ad->busy_slot >= AHCI_MAX_CMDS) {
                 return -1;
             }
-            ad->cur_cmd = &((AHCICmdHdr *)ad->lst)[ad->busy_slot];
+            ad->cur_cmd = get_cmd_header(s, i, ad->busy_slot);
         }
     }
 
-- 
2.1.0