[1/3] ide: don't lose pending dma state
diff mbox

Message ID 1459165702-755-2-git-send-email-den@openvz.org
State New
Headers show

Commit Message

Denis V. Lunev March 28, 2016, 11:48 a.m. UTC
From: Pavel Butsykin <pbutsykin@virtuozzo.com>

If the migration occurs after the IDE DMA has been set up but before it
has been initiated, the state gets lost upon save/restore. Specifically,
->dma_cb callback gets cleared, so, when the guest eventually starts bus
mastering, the DMA never completes, causing the guest to time out the
operation.

OTOH all the infrastructure is already in place to restart the DMA if
the migration happens while the DMA is in progress.

So reuse that infrastructure, by setting bus->error_status based on
->dma_cmd in pre_save if ->dma_cb callback is already set but DMAING is
clear. This will indicate the need for restart and make sure ->dma_cb is
restored in ide_restart_bh(); however since DMAING is clear the state
upon restore will be exactly "ready for DMA" as before the save.

Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: John Snow <jsnow@redhat.com>
---
 hw/ide/core.c     |  9 +--------
 hw/ide/internal.h | 15 +++++++++++++++
 hw/ide/pci.c      |  4 ++++
 3 files changed, 20 insertions(+), 8 deletions(-)

Comments

John Snow March 30, 2016, 5:53 p.m. UTC | #1
On 03/28/2016 07:48 AM, Denis V. Lunev wrote:
> From: Pavel Butsykin <pbutsykin@virtuozzo.com>
> 
> If the migration occurs after the IDE DMA has been set up but before it
> has been initiated, the state gets lost upon save/restore. Specifically,
> ->dma_cb callback gets cleared, so, when the guest eventually starts bus
> mastering, the DMA never completes, causing the guest to time out the
> operation.
> 
> OTOH all the infrastructure is already in place to restart the DMA if
> the migration happens while the DMA is in progress.
> 
> So reuse that infrastructure, by setting bus->error_status based on
> ->dma_cmd in pre_save if ->dma_cb callback is already set but DMAING is
> clear. This will indicate the need for restart and make sure ->dma_cb is
> restored in ide_restart_bh(); however since DMAING is clear the state
> upon restore will be exactly "ready for DMA" as before the save.
> 
> Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com>
> Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: John Snow <jsnow@redhat.com>
> ---
>  hw/ide/core.c     |  9 +--------
>  hw/ide/internal.h | 15 +++++++++++++++
>  hw/ide/pci.c      |  4 ++++
>  3 files changed, 20 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index 241e840..8f86036 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -803,14 +803,7 @@ static void ide_dma_cb(void *opaque, int ret)
>          return;
>      }
>      if (ret < 0) {
> -        int op = IDE_RETRY_DMA;
> -
> -        if (s->dma_cmd == IDE_DMA_READ)
> -            op |= IDE_RETRY_READ;
> -        else if (s->dma_cmd == IDE_DMA_TRIM)
> -            op |= IDE_RETRY_TRIM;
> -
> -        if (ide_handle_rw_error(s, -ret, op)) {
> +        if (ide_handle_rw_error(s, -ret, ide_dma_cmd_to_retry(s->dma_cmd))) {
>              return;
>          }
>      }
> diff --git a/hw/ide/internal.h b/hw/ide/internal.h
> index 86bde26..68c7d0d 100644
> --- a/hw/ide/internal.h
> +++ b/hw/ide/internal.h
> @@ -513,6 +513,21 @@ struct IDEDevice {
>  #define IDE_RETRY_TRIM 0x80
>  #define IDE_RETRY_HBA  0x100
>  
> +static inline uint8_t ide_dma_cmd_to_retry(uint8_t dma_cmd)
> +{
> +    switch (dma_cmd) {
> +    case IDE_DMA_READ:
> +        return IDE_RETRY_DMA | IDE_RETRY_READ;
> +    case IDE_DMA_WRITE:
> +        return IDE_RETRY_DMA;
> +    case IDE_DMA_TRIM:
> +        return IDE_RETRY_DMA | IDE_RETRY_TRIM;
> +    default:
> +        break;
> +    }
> +    return 0;
> +}
> +
>  static inline IDEState *idebus_active_if(IDEBus *bus)
>  {
>      return bus->ifs + bus->unit;
> diff --git a/hw/ide/pci.c b/hw/ide/pci.c
> index 92ffee7..8d56a00 100644
> --- a/hw/ide/pci.c
> +++ b/hw/ide/pci.c
> @@ -308,6 +308,10 @@ static void ide_bmdma_pre_save(void *opaque)
>      BMDMAState *bm = opaque;
>      uint8_t abused_bits = BM_MIGRATION_COMPAT_STATUS_BITS;
>  
> +    if (!(bm->status & BM_STATUS_DMAING) && bm->dma_cb) {
> +        bm->bus->error_status =
> +            ide_dma_cmd_to_retry(bmdma_active_if(bm)->dma_cmd);
> +    }
>      bm->migration_retry_unit = bm->bus->retry_unit;
>      bm->migration_retry_sector_num = bm->bus->retry_sector_num;
>      bm->migration_retry_nsector = bm->bus->retry_nsector;
> 

_this_ is the one I meant to R-B, thanks Denis. (Testing the others now,
but having some laptop issues. Please stand by.)

Reviewed-by: John Snow <jsnow@redhat.com>

Patch
diff mbox

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 241e840..8f86036 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -803,14 +803,7 @@  static void ide_dma_cb(void *opaque, int ret)
         return;
     }
     if (ret < 0) {
-        int op = IDE_RETRY_DMA;
-
-        if (s->dma_cmd == IDE_DMA_READ)
-            op |= IDE_RETRY_READ;
-        else if (s->dma_cmd == IDE_DMA_TRIM)
-            op |= IDE_RETRY_TRIM;
-
-        if (ide_handle_rw_error(s, -ret, op)) {
+        if (ide_handle_rw_error(s, -ret, ide_dma_cmd_to_retry(s->dma_cmd))) {
             return;
         }
     }
diff --git a/hw/ide/internal.h b/hw/ide/internal.h
index 86bde26..68c7d0d 100644
--- a/hw/ide/internal.h
+++ b/hw/ide/internal.h
@@ -513,6 +513,21 @@  struct IDEDevice {
 #define IDE_RETRY_TRIM 0x80
 #define IDE_RETRY_HBA  0x100
 
+static inline uint8_t ide_dma_cmd_to_retry(uint8_t dma_cmd)
+{
+    switch (dma_cmd) {
+    case IDE_DMA_READ:
+        return IDE_RETRY_DMA | IDE_RETRY_READ;
+    case IDE_DMA_WRITE:
+        return IDE_RETRY_DMA;
+    case IDE_DMA_TRIM:
+        return IDE_RETRY_DMA | IDE_RETRY_TRIM;
+    default:
+        break;
+    }
+    return 0;
+}
+
 static inline IDEState *idebus_active_if(IDEBus *bus)
 {
     return bus->ifs + bus->unit;
diff --git a/hw/ide/pci.c b/hw/ide/pci.c
index 92ffee7..8d56a00 100644
--- a/hw/ide/pci.c
+++ b/hw/ide/pci.c
@@ -308,6 +308,10 @@  static void ide_bmdma_pre_save(void *opaque)
     BMDMAState *bm = opaque;
     uint8_t abused_bits = BM_MIGRATION_COMPAT_STATUS_BITS;
 
+    if (!(bm->status & BM_STATUS_DMAING) && bm->dma_cb) {
+        bm->bus->error_status =
+            ide_dma_cmd_to_retry(bmdma_active_if(bm)->dma_cmd);
+    }
     bm->migration_retry_unit = bm->bus->retry_unit;
     bm->migration_retry_sector_num = bm->bus->retry_sector_num;
     bm->migration_retry_nsector = bm->bus->retry_nsector;