[Qemu-devel] [PULL 4/4] ide: really restart pending and in-flight atapi dma

[John Snow <jsnow@redhat.com>]

From: Pavel Butsykin <pbutsykin@virtuozzo.com>

Restart of ATAPI DMA used to be unreachable, because the request to do
so wasn't indicated in bus->error_status due to the lack of spare bits, and
ide_restart_bh() would return early doing nothing.

This patch makes use of the observation that not all bit combinations were
possible in ->error_status. In particular, IDE_RETRY_READ only made sense
together with IDE_RETRY_DMA or IDE_RETRY_PIO. This allows to re-use
IDE_RETRY_READ alone as an indicator of ATAPI DMA restart request.

To makes things more uniform, ATAPI DMA gets its own value for ->dma_cmd.
As a means against confusion, macros are added to test the state of
->error_status.

The patch fixes the restart of both in-flight and pending ATAPI DMA,
following the scheme similar to that of IDE DMA.

[Including a fixup patch:
Message-id: 1460465594-15777-1-git-send-email-pbutsykin@virtuozzo.com
--js]

Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1459924806-306-4-git-send-email-den@openvz.org
Signed-off-by: John Snow <jsnow@redhat.com>
---
 hw/ide/atapi.c    | 13 ++++++-------
 hw/ide/core.c     | 30 +++++++++++++++---------------
 hw/ide/internal.h | 20 ++++++++++++++++++++
 hw/ide/macio.c    |  2 ++
 4 files changed, 43 insertions(+), 22 deletions(-)

diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
index acc52cd..2bb606c 100644
--- a/hw/ide/atapi.c
+++ b/hw/ide/atapi.c
@@ -375,15 +375,18 @@ static void ide_atapi_cmd_check_status(IDEState *s)
 }
 /* ATAPI DMA support */
 
-/* XXX: handle read errors */
 static void ide_atapi_cmd_read_dma_cb(void *opaque, int ret)
 {
     IDEState *s = opaque;
     int data_offset, n;
 
     if (ret < 0) {
-        ide_atapi_io_error(s, ret);
-        goto eot;
+        if (ide_handle_rw_error(s, -ret, ide_dma_cmd_to_retry(s->dma_cmd))) {
+            if (s->bus->error_status) {
+                return;
+            }
+            goto eot;
+        }
     }
 
     if (s->io_buffer_size > 0) {
@@ -481,10 +484,6 @@ static void ide_atapi_cmd_read(IDEState *s, int lba, int nb_sectors,
     }
 }
 
-
-/* Called by *_restart_bh when the transfer function points
- * to ide_atapi_cmd
- */
 void ide_atapi_dma_restart(IDEState *s)
 {
     /*
diff --git a/hw/ide/core.c b/hw/ide/core.c
index 58d0687..41e6a2d 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -57,7 +57,6 @@ static const int smart_attributes[][12] = {
     { 190,  0x03, 0x00, 0x45, 0x45, 0x1f, 0x00, 0x1f, 0x1f, 0x00, 0x00, 0x32},
 };
 
-static int ide_handle_rw_error(IDEState *s, int error, int op);
 static void ide_dummy_transfer_stop(IDEState *s);
 
 static void padstr(char *str, const char *src, int len)
@@ -773,7 +772,7 @@ void ide_dma_error(IDEState *s)
     ide_set_irq(s->bus);
 }
 
-static int ide_handle_rw_error(IDEState *s, int error, int op)
+int ide_handle_rw_error(IDEState *s, int error, int op)
 {
     bool is_read = (op & IDE_RETRY_READ) != 0;
     BlockErrorAction action = blk_get_error_action(s->blk, is_read, error);
@@ -783,8 +782,10 @@ static int ide_handle_rw_error(IDEState *s, int error, int op)
         s->bus->error_status = op;
     } else if (action == BLOCK_ERROR_ACTION_REPORT) {
         block_acct_failed(blk_get_stats(s->blk), &s->acct);
-        if (op & IDE_RETRY_DMA) {
+        if (IS_IDE_RETRY_DMA(op)) {
             ide_dma_error(s);
+        } else if (IS_IDE_RETRY_ATAPI(op)) {
+            ide_atapi_io_error(s, -error);
         } else {
             ide_rw_error(s);
         }
@@ -872,6 +873,8 @@ static void ide_dma_cb(void *opaque, int ret)
                                         ide_issue_trim, ide_dma_cb, s,
                                         DMA_DIRECTION_TO_DEVICE);
         break;
+    default:
+        abort();
     }
     return;
 
@@ -1634,6 +1637,9 @@ static bool cmd_packet(IDEState *s, uint8_t cmd)
 
     s->status = READY_STAT | SEEK_STAT;
     s->atapi_dma = s->feature & 1;
+    if (s->atapi_dma) {
+        s->dma_cmd = IDE_DMA_ATAPI;
+    }
     s->nsector = 1;
     ide_transfer_start(s, s->io_buffer, ATAPI_PACKET_SIZE,
                        ide_atapi_cmd);
@@ -2518,15 +2524,13 @@ static void ide_restart_bh(void *opaque)
         if (s->bus->dma->ops->restart) {
             s->bus->dma->ops->restart(s->bus->dma);
         }
-    }
-
-    if (error_status & IDE_RETRY_DMA) {
+    } else if (IS_IDE_RETRY_DMA(error_status)) {
         if (error_status & IDE_RETRY_TRIM) {
             ide_restart_dma(s, IDE_DMA_TRIM);
         } else {
             ide_restart_dma(s, is_read ? IDE_DMA_READ : IDE_DMA_WRITE);
         }
-    } else if (error_status & IDE_RETRY_PIO) {
+    } else if (IS_IDE_RETRY_PIO(error_status)) {
         if (is_read) {
             ide_sector_read(s);
         } else {
@@ -2534,15 +2538,11 @@ static void ide_restart_bh(void *opaque)
         }
     } else if (error_status & IDE_RETRY_FLUSH) {
         ide_flush_cache(s);
+    } else if (IS_IDE_RETRY_ATAPI(error_status)) {
+        assert(s->end_transfer_func == ide_atapi_cmd);
+        ide_atapi_dma_restart(s);
     } else {
-        /*
-         * We've not got any bits to tell us about ATAPI - but
-         * we do have the end_transfer_func that tells us what
-         * we're trying to do.
-         */
-        if (s->end_transfer_func == ide_atapi_cmd) {
-            ide_atapi_dma_restart(s);
-        }
+        abort();
     }
 }
 
diff --git a/hw/ide/internal.h b/hw/ide/internal.h
index 68c7d0d..d2c458f 100644
--- a/hw/ide/internal.h
+++ b/hw/ide/internal.h
@@ -338,6 +338,7 @@ enum ide_dma_cmd {
     IDE_DMA_READ,
     IDE_DMA_WRITE,
     IDE_DMA_TRIM,
+    IDE_DMA_ATAPI,
 };
 
 #define ide_cmd_is_read(s) \
@@ -506,13 +507,28 @@ struct IDEDevice {
 };
 
 /* These are used for the error_status field of IDEBus */
+#define IDE_RETRY_MASK 0xf8
 #define IDE_RETRY_DMA  0x08
 #define IDE_RETRY_PIO  0x10
+#define IDE_RETRY_ATAPI 0x20 /* reused IDE_RETRY_READ bit */
 #define IDE_RETRY_READ  0x20
 #define IDE_RETRY_FLUSH 0x40
 #define IDE_RETRY_TRIM 0x80
 #define IDE_RETRY_HBA  0x100
 
+#define IS_IDE_RETRY_DMA(_status) \
+    ((_status) & IDE_RETRY_DMA)
+
+#define IS_IDE_RETRY_PIO(_status) \
+    ((_status) & IDE_RETRY_PIO)
+
+/*
+ * The method of the IDE_RETRY_ATAPI determination is to use a previously
+ * impossible bit combination as a new status value.
+ */
+#define IS_IDE_RETRY_ATAPI(_status)   \
+    (((_status) & IDE_RETRY_MASK) == IDE_RETRY_ATAPI)
+
 static inline uint8_t ide_dma_cmd_to_retry(uint8_t dma_cmd)
 {
     switch (dma_cmd) {
@@ -522,6 +538,8 @@ static inline uint8_t ide_dma_cmd_to_retry(uint8_t dma_cmd)
         return IDE_RETRY_DMA;
     case IDE_DMA_TRIM:
         return IDE_RETRY_DMA | IDE_RETRY_TRIM;
+    case IDE_DMA_ATAPI:
+        return IDE_RETRY_ATAPI;
     default:
         break;
     }
@@ -612,4 +630,6 @@ void ide_bus_new(IDEBus *idebus, size_t idebus_size, DeviceState *dev,
                  int bus_id, int max_units);
 IDEDevice *ide_create_drive(IDEBus *bus, int unit, DriveInfo *drive);
 
+int ide_handle_rw_error(IDEState *s, int error, int op);
+
 #endif /* HW_IDE_INTERNAL_H */
diff --git a/hw/ide/macio.c b/hw/ide/macio.c
index 1725e5b..76256eb 100644
--- a/hw/ide/macio.c
+++ b/hw/ide/macio.c
@@ -346,6 +346,8 @@ static void pmac_ide_transfer_cb(void *opaque, int ret)
     case IDE_DMA_TRIM:
         pmac_dma_trim(s->blk, offset, io->len, pmac_ide_transfer_cb, io);
         break;
+    default:
+        abort();
     }
 
     return;
-- 
2.4.11