[Qemu-devel] [PATCH v3 0/2] Correct transitions for cd change state

[Qemu-devel] [PATCH v3 0/2] Correct transitions for cd change state

[Amit Shah]

Hello,

These two patches fix the cd media size change bugs.

The test scenario is:

1. create an iso image from a file
2. create a second iso image from a bigger file
3. mount 1st cd in guest
4. unmount it
5. change cd via qemu monitor
6. mount 2nd cd
7. copy file on cd to local disk -- shows errors.

v2: Set media_change_notified to 1 if SENSE_UNIT_ATTENTION is not set
after migration.  This is the only thing needed for migration compat.

v3:
 - Use cdrom_changed to hold all state changes instead of introducing
   a new variable. (Paolo Bonzini)
 - Slightly better comment and commit messages

Please apply.

Amit Shah (2):
  cdrom: Allow the TEST_UNIT_READY command after a cdrom change
  cdrom: Make disc change event visible to guests

 hw/ide/core.c |   56 +++++++++++++++++++++++++++++++++++++++++++++++---------
 1 files changed, 47 insertions(+), 9 deletions(-)

-- 
1.7.4

[Qemu-devel] [PATCH v3 1/2] cdrom: Allow the TEST_UNIT_READY command after a cdrom change

[Amit Shah]

We restrict the commands that a guest can send us after a cdrom change
event.  The current list includes REQUEST_SENSE and INQUIRY commands.
Guests can also issue TEST_UNIT_READY to inquire for the status, so
allow this command as well.

This also gets rid of one cause of the HSM violation errors in Linux
guests.  Those errors came up because we had the UNIT_ATTENTION event
pending and we replied with an error message to a command that should be
allowed in such a condition.  The guest then did a soft reset to get to
a sane state.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/ide/core.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 007a4ee..d55d804 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1105,10 +1105,11 @@ static void ide_atapi_cmd(IDEState *s)
     /* If there's a UNIT_ATTENTION condition pending, only
        REQUEST_SENSE and INQUIRY commands are allowed to complete. */
     if (s->sense_key == SENSE_UNIT_ATTENTION &&
-	s->io_buffer[0] != GPCMD_REQUEST_SENSE &&
-	s->io_buffer[0] != GPCMD_INQUIRY) {
-	ide_atapi_cmd_check_status(s);
-	return;
+        s->io_buffer[0] != GPCMD_REQUEST_SENSE &&
+        s->io_buffer[0] != GPCMD_INQUIRY &&
+        s->io_buffer[0] != GPCMD_TEST_UNIT_READY) {
+        ide_atapi_cmd_check_status(s);
+        return;
     }
     switch(s->io_buffer[0]) {
     case GPCMD_TEST_UNIT_READY:
-- 
1.7.4

Re: [Qemu-devel] [PATCH v3 1/2] cdrom: Allow the TEST_UNIT_READY command after a cdrom change

[Ryan Harper]

* Amit Shah <amit.shah@redhat.com> [2011-04-07 03:53]:
> We restrict the commands that a guest can send us after a cdrom change
> event.  The current list includes REQUEST_SENSE and INQUIRY commands.
> Guests can also issue TEST_UNIT_READY to inquire for the status, so
> allow this command as well.
> 
> This also gets rid of one cause of the HSM violation errors in Linux
> guests.  Those errors came up because we had the UNIT_ATTENTION event
> pending and we replied with an error message to a command that should be
> allowed in such a condition.  The guest then did a soft reset to get to
> a sane state.
> 
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
>  hw/ide/core.c |    9 +++++----
>  1 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index 007a4ee..d55d804 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -1105,10 +1105,11 @@ static void ide_atapi_cmd(IDEState *s)
>      /* If there's a UNIT_ATTENTION condition pending, only
>         REQUEST_SENSE and INQUIRY commands are allowed to complete. */

Wasn't this comment going to get updated to be more generic (ie more
than just the 3 commands below may be needed?)

>      if (s->sense_key == SENSE_UNIT_ATTENTION &&
> -	s->io_buffer[0] != GPCMD_REQUEST_SENSE &&
> -	s->io_buffer[0] != GPCMD_INQUIRY) {
> -	ide_atapi_cmd_check_status(s);
> -	return;
> +        s->io_buffer[0] != GPCMD_REQUEST_SENSE &&
> +        s->io_buffer[0] != GPCMD_INQUIRY &&
> +        s->io_buffer[0] != GPCMD_TEST_UNIT_READY) {
> +        ide_atapi_cmd_check_status(s);
> +        return;
>      }
>      switch(s->io_buffer[0]) {
>      case GPCMD_TEST_UNIT_READY:
> -- 
> 1.7.4
> 

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
ryanh@us.ibm.com

[Qemu-devel] [PATCH v3 2/2] cdrom: Make disc change event visible to guests

[Amit Shah]

Commit 93c8cfd9e67a62711b86f4c93747566885eb7928 sent a 'no disc' event
after a cdrom change so that guests notice a cd change event between two
'cd present' states.  However, we don't follow the 2nd arrow in:

 'cd present' -> 'no cd' -> 'cd present'

as the SENSE_UNIT_ATTENTION sense_key is written over by the
ide_atapi_cmd_error() function.

So for the disc change event, let us ensure the error() function doesn't
trample over that value so we do get to report it the next time around.
Also, ensure we go from 'no cd' to 'cd present' state.

With this, older Linux guests (< 2.6.38) notice cd changes just fine.
For newer Linux guests (2.6.38+) cd change events break again and that
will be fixed by implementing the GET_EVENT_STATUS_NOTIFICATION command.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/ide/core.c |   47 ++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index d55d804..3f00cff 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1113,10 +1113,47 @@ static void ide_atapi_cmd(IDEState *s)
     }
     switch(s->io_buffer[0]) {
     case GPCMD_TEST_UNIT_READY:
-        if (bdrv_is_inserted(s->bs) && !s->cdrom_changed) {
-            ide_atapi_cmd_ok(s);
+        if (bdrv_is_inserted(s->bs)) {
+            int sense, asc;
+
+            sense = s->sense_key;
+            asc = s->asc;
+
+            /*
+             * Check if there's any pending media change notification
+             * to be given.
+             *
+             * We want the guest to notice an empty tray after a cd
+             * change, so that the guest can trigger its new media
+             * paths.  So send one MEDIUM_NOT_PRESENT message after a
+             * cd change.
+             *
+             * After we've sent that message, the guest will poke at
+             * us again.  Send the UNIT_ATTENTION message then.  Once
+             * this is done, reset the UNIT_ATTENTION message to
+             * ensure we don't keep repeating it.
+             */
+            switch(s->cdrom_changed) {
+            case 0:
+                ide_atapi_cmd_ok(s);
+                break;
+            case 1:
+                s->sense_key = SENSE_UNIT_ATTENTION;
+                s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED;
+                ide_atapi_cmd_ok(s);
+
+		sense = SENSE_NONE;
+                s->cdrom_changed--;
+                break;
+            case 2:
+                ide_atapi_cmd_error(s, SENSE_NOT_READY,
+                                    ASC_MEDIUM_NOT_PRESENT);
+                s->cdrom_changed--;
+                break;
+            }
+            s->sense_key = sense;
+            s->asc = asc;
         } else {
-            s->cdrom_changed = 0;
             ide_atapi_cmd_error(s, SENSE_NOT_READY,
                                 ASC_MEDIUM_NOT_PRESENT);
         }
@@ -1612,7 +1649,7 @@ static void cdrom_change_cb(void *opaque, int reason)
 
     s->sense_key = SENSE_UNIT_ATTENTION;
     s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED;
-    s->cdrom_changed = 1;
+    s->cdrom_changed = 2;
     ide_set_irq(s->bus);
 }
 
@@ -2712,7 +2749,7 @@ static int ide_drive_post_load(void *opaque, int version_id)
     if (version_id < 3) {
         if (s->sense_key == SENSE_UNIT_ATTENTION &&
             s->asc == ASC_MEDIUM_MAY_HAVE_CHANGED) {
-            s->cdrom_changed = 1;
+            s->cdrom_changed = 2;
         }
     }
     return 0;
-- 
1.7.4

[Qemu-devel] Re: [PATCH v3 0/2] Correct transitions for cd change state

[Stefan Hajnoczi]

Windows Server 2003 works - media change is detected and size is
updated correctly.

Tested-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

[Qemu-devel] Re: [PATCH v3 0/2] Correct transitions for cd change state

[Paolo Bonzini]

On 04/07/2011 10:46 AM, Amit Shah wrote:
> Hello,
>
> These two patches fix the cd media size change bugs.
>
> The test scenario is:
>
> 1. create an iso image from a file
> 2. create a second iso image from a bigger file
> 3. mount 1st cd in guest
> 4. unmount it
> 5. change cd via qemu monitor
> 6. mount 2nd cd
> 7. copy file on cd to local disk -- shows errors.
>
> v2: Set media_change_notified to 1 if SENSE_UNIT_ATTENTION is not set
> after migration.  This is the only thing needed for migration compat.
>
> v3:
>   - Use cdrom_changed to hold all state changes instead of introducing
>     a new variable. (Paolo Bonzini)
>   - Slightly better comment and commit messages
>
> Please apply.
>
> Amit Shah (2):
>    cdrom: Allow the TEST_UNIT_READY command after a cdrom change
>    cdrom: Make disc change event visible to guests
>
>   hw/ide/core.c |   56 +++++++++++++++++++++++++++++++++++++++++++++++---------
>   1 files changed, 47 insertions(+), 9 deletions(-)
>

Thanks!

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

Paolo