[Qemu-devel] [PATCH v2 0/6] atapi: Implement 'media' subcommand for GESN

[Qemu-devel] [PATCH v2 0/6] atapi: Implement 'media' subcommand for GESN

[Amit Shah]

The GET_EVENT_STATUS_NOTIFICATION ATAPI command is listed as a
mandatory command in the spec but we don't really implement it any of
its sub-commands.

The commit message for the last commit explains why implementing just
the media subcommand is helpful and how it goes a long way in getting
guests to behave as expected.

The difference from the RFC series sent earlier is:
- Split into more patches
- Add tray open/close notification (from Markus)

There certainly is much more work to be done for the other commands
and also for state change handling (tray open / close / new media)
overall for the block layer, but this is a good first step in being
spec-compliant and at the same time making guests work.

v2:
 - Update comments
 - Use struct instead of enum for cdb packet
 - Add a new subsection to vmstate for new fields for save/restore

v1:
 - Split into more patches
 - Add tray open/close notification (from Markus)

RFC:
 - Orig. series


Amit Shah (6):
  atapi: Allow GET_EVENT_STATUS_NOTIFICATION after media change
  atapi: Move GET_EVENT_STATUS_NOTIFICATION command handling to its own
    function
  atapi: GESN: Spin off No Event Available handling into own function
  atapi: GESN: Use structs for commonly-used field types
  atapi: GESN: implement 'media' subcommand
  atapi: Save / load the new GESN event states during migration

 hw/ide/core.c     |  186 +++++++++++++++++++++++++++++++++++++++++++++++------
 hw/ide/internal.h |    6 ++
 2 files changed, 173 insertions(+), 19 deletions(-)

-- 
1.7.4.2

[Qemu-devel] [PATCH v2 1/6] atapi: Allow GESN after media change

[Amit Shah]

After a media change, the only commands allowed from the guest were
REQUEST_SENSE and INQUIRY.  The guest may also issue
GET_EVENT_STATUS_NOTIFICATION commands to get media
changed notification.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/ide/core.c |   19 +++++++++++++------
 1 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index c11d457..f839ef3 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1102,13 +1102,20 @@ static void ide_atapi_cmd(IDEState *s)
         printf("\n");
     }
 #endif
-    /* If there's a UNIT_ATTENTION condition pending, only
-       REQUEST_SENSE and INQUIRY commands are allowed to complete. */
+    /*
+     * If there's a UNIT_ATTENTION condition pending, only
+     * REQUEST_SENSE, INQUIRY and GET_EVENT_STATUS_NOTIFICATION
+     * commands are allowed to complete.  MMC-5, section 4.1.6.1 lists
+     * only these commands being allowed to complete, with other
+     * commands getting a CHECK condition response unless a higher
+     * priority status, defined by the drive here, is pending.
+     */
     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_GET_EVENT_STATUS_NOTIFICATION) {
+        ide_atapi_cmd_check_status(s);
+        return;
     }
     switch(s->io_buffer[0]) {
     case GPCMD_TEST_UNIT_READY:
-- 
1.7.4.2

[Qemu-devel] [PATCH v2 2/6] atapi: Move GET_EVENT_STATUS_NOTIFICATION command handling to its own function

[Amit Shah]

This makes the code more readable.

Also, there's a block like:

if () {
  ...
} else {
  ...
}

Split that into

if () {
  ...
  return;
}
...

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/ide/core.c |   37 ++++++++++++++++++++++++-------------
 1 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index f839ef3..d71bc41 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1084,6 +1084,29 @@ static int ide_dvd_read_structure(IDEState *s, int format,
     }
 }
 
+static void handle_get_event_status_notification(IDEState *s,
+                                                 uint8_t *buf,
+                                                 const uint8_t *packet)
+{
+    unsigned int max_len;
+
+    max_len = ube16_to_cpu(packet + 7);
+
+    if (!(packet[1] & 0x01)) { /* asynchronous mode */
+        /* Only polling is supported, asynchronous mode is not. */
+        ide_atapi_cmd_error(s, SENSE_ILLEGAL_REQUEST,
+                            ASC_INV_FIELD_IN_CMD_PACKET);
+        return;
+    }
+
+    /* polling */
+    /* We don't support any event class (yet). */
+    cpu_to_ube16(buf, 0x00); /* No event descriptor returned */
+    buf[2] = 0x80;           /* No Event Available (NEA) */
+    buf[3] = 0x00;           /* Empty supported event classes */
+    ide_atapi_cmd_reply(s, 4, max_len);
+}
+
 static void ide_atapi_cmd(IDEState *s)
 {
     const uint8_t *packet;
@@ -1529,19 +1552,7 @@ static void ide_atapi_cmd(IDEState *s)
             break;
         }
     case GPCMD_GET_EVENT_STATUS_NOTIFICATION:
-        max_len = ube16_to_cpu(packet + 7);
-
-        if (packet[1] & 0x01) { /* polling */
-            /* We don't support any event class (yet). */
-            cpu_to_ube16(buf, 0x00); /* No event descriptor returned */
-            buf[2] = 0x80;           /* No Event Available (NEA) */
-            buf[3] = 0x00;           /* Empty supported event classes */
-            ide_atapi_cmd_reply(s, 4, max_len);
-        } else { /* asynchronous mode */
-            /* Only polling is supported, asynchronous mode is not. */
-            ide_atapi_cmd_error(s, SENSE_ILLEGAL_REQUEST,
-                                ASC_INV_FIELD_IN_CMD_PACKET);
-        }
+        handle_get_event_status_notification(s, buf, packet);
         break;
     default:
         ide_atapi_cmd_error(s, SENSE_ILLEGAL_REQUEST,
-- 
1.7.4.2

[Qemu-devel] [PATCH v2 3/6] atapi: GESN: Spin off No Event Available handling into own function

[Amit Shah]

Handle GET_EVENT_STATUS_NOTIFICATION's No Event Available status in its
own function.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/ide/core.c |   21 +++++++++++++++------
 1 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index d71bc41..c5913d8 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1084,14 +1084,24 @@ static int ide_dvd_read_structure(IDEState *s, int format,
     }
 }
 
+static unsigned int event_status_nea(uint8_t *buf, unsigned int max_len)
+{
+    cpu_to_ube16(buf, 0x00); /* No event descriptor returned */
+    buf[2] = 0x80;           /* No Event Available (NEA) */
+    buf[3] = 0x00;           /* Empty supported event classes */
+
+    return 4; /* We wrote to 4 bytes */
+}
+
 static void handle_get_event_status_notification(IDEState *s,
                                                  uint8_t *buf,
                                                  const uint8_t *packet)
 {
-    unsigned int max_len;
+    unsigned int max_len, used_len;
 
     max_len = ube16_to_cpu(packet + 7);
 
+    /* It is fine by the MMC spec to not support async mode operations */
     if (!(packet[1] & 0x01)) { /* asynchronous mode */
         /* Only polling is supported, asynchronous mode is not. */
         ide_atapi_cmd_error(s, SENSE_ILLEGAL_REQUEST,
@@ -1099,12 +1109,11 @@ static void handle_get_event_status_notification(IDEState *s,
         return;
     }
 
-    /* polling */
+    /* polling mode operation */
+
     /* We don't support any event class (yet). */
-    cpu_to_ube16(buf, 0x00); /* No event descriptor returned */
-    buf[2] = 0x80;           /* No Event Available (NEA) */
-    buf[3] = 0x00;           /* Empty supported event classes */
-    ide_atapi_cmd_reply(s, 4, max_len);
+    used_len = event_status_nea(buf, max_len);
+    ide_atapi_cmd_reply(s, used_len, max_len);
 }
 
 static void ide_atapi_cmd(IDEState *s)
-- 
1.7.4.2

[Qemu-devel] [PATCH v2 4/6] atapi: GESN: Use structs for commonly-used field types

[Amit Shah]

Instead of using magic numbers, use structs that are more descriptive of
the fields being used.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/ide/core.c |   15 +++++++++++++--
 1 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index c5913d8..fe50d8a 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1097,12 +1097,23 @@ static void handle_get_event_status_notification(IDEState *s,
                                                  uint8_t *buf,
                                                  const uint8_t *packet)
 {
+    struct {
+        uint8_t opcode;
+        uint8_t polled;   /* lsb bit is polled; others are reserved */
+        uint8_t reserved2[2];
+        uint8_t request;
+        uint8_t reserved3[2];
+        uint8_t len_msb;
+        uint8_t len_lsb;
+        uint8_t control;
+    } __attribute__((packed)) *gesn_cdb;
     unsigned int max_len, used_len;
 
-    max_len = ube16_to_cpu(packet + 7);
+    gesn_cdb = (void *)packet;
+    max_len = ube16_to_cpu(&gesn_cdb->len_msb);
 
     /* It is fine by the MMC spec to not support async mode operations */
-    if (!(packet[1] & 0x01)) { /* asynchronous mode */
+    if (!(gesn_cdb->polled & 0x01)) { /* asynchronous mode */
         /* Only polling is supported, asynchronous mode is not. */
         ide_atapi_cmd_error(s, SENSE_ILLEGAL_REQUEST,
                             ASC_INV_FIELD_IN_CMD_PACKET);
-- 
1.7.4.2

[Qemu-devel] [PATCH v2 5/6] atapi: GESN: implement 'media' subcommand

[Amit Shah]

Implement the 'media' sub-command of the GET_EVENT_STATUS_NOTIFICATION
command.  This helps us report tray open, tray closed, no media, media
present states to the guest.

Newer Linux kernels (2.6.38+) rely on this command to revalidate discs
after media change.

This patch also sends out tray open/closed status to the guest driver
when requested e.g. via the CDROM_DRIVE_STATUS ioctl (thanks Markus).
Without such notification, the guest and qemu's tray open/close status
was frequently out of sync, causing installers like Anaconda detecting
no disc instead of tray open, confusing them terribly.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/ide/core.c     |   92 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 hw/ide/internal.h |    6 +++
 2 files changed, 96 insertions(+), 2 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index fe50d8a..2683070 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1084,6 +1084,47 @@ static int ide_dvd_read_structure(IDEState *s, int format,
     }
 }
 
+static unsigned int event_status_media(IDEState *s,
+                                       uint8_t *buf,
+                                       unsigned int max_len,
+                                       unsigned int event_class,
+                                       unsigned int supported_events)
+{
+    enum media_event_code {
+        no_change = 0,       /* Status unchanged */
+        eject_requested,     /* received a request from user to eject */
+        new_media,           /* new media inserted and ready for access */
+        media_removal,       /* only for media changers */
+        media_changed,       /* only for media changers */
+        bg_format_completed, /* MRW or DVD+RW b/g format completed */
+        bg_format_restarted, /* MRW or DVD+RW b/g format restarted */
+    };
+    enum media_status {
+        tray_open = 1,
+        media_present = 2,
+    };
+    uint8_t event_code, media_status;
+
+    media_status = 0;
+    if (s->bs->tray_open) {
+        media_status = tray_open;
+    } else if (bdrv_is_inserted(s->bs)) {
+        media_status = media_present;
+    }
+
+    /* Event notification descriptor */
+    event_code = no_change;
+    if (media_status != tray_open && s->events.new_media) {
+        event_code = new_media;
+        s->events.new_media = false;
+    }
+
+    buf[4] = event_code;
+    buf[5] = media_status;
+
+    return 6; /* We wrote to just 2 extra bytes from the header */
+}
+
 static unsigned int event_status_nea(uint8_t *buf, unsigned int max_len)
 {
     cpu_to_ube16(buf, 0x00); /* No event descriptor returned */
@@ -1107,7 +1148,28 @@ static void handle_get_event_status_notification(IDEState *s,
         uint8_t len_lsb;
         uint8_t control;
     } __attribute__((packed)) *gesn_cdb;
+    enum notification_class_request_type {
+        reserved1 = 1 << 0,
+        operational_change = 1 << 1,
+        power_management = 1 << 2,
+        external_request = 1 << 3,
+        media = 1 << 4,
+        multi_host = 1 << 5,
+        device_busy = 1 << 6,
+        reserved2 = 1 << 7,
+    };
+    enum event_notification_class_field {
+        enc_no_events = 0,
+        enc_operational_change,
+        enc_power_management,
+        enc_external_request,
+        enc_media,
+        enc_multiple_hosts,
+        enc_device_busy,
+        enc_reserved,
+    };
     unsigned int max_len, used_len;
+    unsigned int supported_events;
 
     gesn_cdb = (void *)packet;
     max_len = ube16_to_cpu(&gesn_cdb->len_msb);
@@ -1122,8 +1184,33 @@ static void handle_get_event_status_notification(IDEState *s,
 
     /* polling mode operation */
 
-    /* We don't support any event class (yet). */
-    used_len = event_status_nea(buf, max_len);
+    /*
+     * These are the supported events.
+     *
+     * We currently only support requests of the 'media' type.
+     */
+    supported_events = media;
+
+    /*
+     * Event notification header; will be overwritten by the
+     * NO_EVENT_AVAILABLE code if we don't have events: according to
+     * MMC-5 6.7.2.2, if nea = 1, event class field should be 0.
+     */
+    cpu_to_ube16(buf, max_len);
+    buf[2] = event_class;
+    buf[3] = supported_events;
+
+    /*
+     * Responses to requests are to be based on request priority.  The
+     * notification_class_request_type enum above specifies the
+     * priority: upper elements are higher prio than lower ones.
+     */
+    if (gesn_cdb->request & media) {
+        used_len = event_status_media(s, buf, max_len, enc_media,
+                                      supported_events);
+    } else {
+        used_len = event_status_nea(buf, max_len);
+    }
     ide_atapi_cmd_reply(s, used_len, max_len);
 }
 
@@ -1650,6 +1737,7 @@ 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->events.new_media = true;
     ide_set_irq(s->bus);
 }
 
diff --git a/hw/ide/internal.h b/hw/ide/internal.h
index d533fb6..ba7e9a8 100644
--- a/hw/ide/internal.h
+++ b/hw/ide/internal.h
@@ -373,6 +373,11 @@ typedef int DMAFunc(IDEDMA *);
 typedef int DMAIntFunc(IDEDMA *, int);
 typedef void DMARestartFunc(void *, int, int);
 
+struct unreported_events {
+    bool eject_request;
+    bool new_media;
+};
+
 /* NOTE: IDEState represents in fact one drive */
 struct IDEState {
     IDEBus *bus;
@@ -408,6 +413,7 @@ struct IDEState {
     BlockDriverState *bs;
     char version[9];
     /* ATAPI specific */
+    struct unreported_events events;
     uint8_t sense_key;
     uint8_t asc;
     uint8_t cdrom_changed;
-- 
1.7.4.2

[Qemu-devel] [PATCH v2 6/6] atapi: Save / load the new GESN event states during migration

[Amit Shah]

Add a new subsection to save and restore the events state for the
GET_EVENT_STATUS_NOTIFICATION command.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/ide/core.c |   22 ++++++++++++++++++++++
 1 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 2683070..7043341 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -2882,6 +2882,25 @@ static bool ide_drive_pio_state_needed(void *opaque)
     return (s->status & DRQ_STAT) != 0;
 }
 
+static bool ide_atapi_gesn_needed(void *opaque)
+{
+    IDEState *s = opaque;
+
+    return s->events.new_media || s->events.eject_request;
+}
+
+/* Fields for GET_EVENT_STATUS_NOTIFICATION ATAPI command */
+const VMStateDescription vmstate_ide_atapi_gesn_state = {
+    .name ="ide_drive/atapi/gesn_state",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields = (VMStateField []) {
+        VMSTATE_BOOL(events.new_media, IDEState),
+        VMSTATE_BOOL(events.eject_request, IDEState),
+    }
+};
+
 const VMStateDescription vmstate_ide_drive_pio_state = {
     .name = "ide_drive/pio_state",
     .version_id = 1,
@@ -2936,6 +2955,9 @@ const VMStateDescription vmstate_ide_drive = {
             .vmsd = &vmstate_ide_drive_pio_state,
             .needed = ide_drive_pio_state_needed,
         }, {
+            .vmsd = &vmstate_ide_atapi_gesn_state,
+            .needed = ide_atapi_gesn_needed,
+        }, {
             /* empty */
         }
     }
-- 
1.7.4.2

Re: [Qemu-devel] [PATCH v2 1/6] atapi: Allow GESN after media change

[Kevin Wolf]

Am 12.04.2011 11:27, schrieb Amit Shah:
> After a media change, the only commands allowed from the guest were
> REQUEST_SENSE and INQUIRY.  The guest may also issue
> GET_EVENT_STATUS_NOTIFICATION commands to get media
> changed notification.
> 
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
>  hw/ide/core.c |   19 +++++++++++++------
>  1 files changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index c11d457..f839ef3 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -1102,13 +1102,20 @@ static void ide_atapi_cmd(IDEState *s)
>          printf("\n");
>      }
>  #endif
> -    /* If there's a UNIT_ATTENTION condition pending, only
> -       REQUEST_SENSE and INQUIRY commands are allowed to complete. */
> +    /*
> +     * If there's a UNIT_ATTENTION condition pending, only
> +     * REQUEST_SENSE, INQUIRY and GET_EVENT_STATUS_NOTIFICATION
> +     * commands are allowed to complete.  MMC-5, section 4.1.6.1 lists
> +     * only these commands being allowed to complete, with other
> +     * commands getting a CHECK condition response unless a higher
> +     * priority status, defined by the drive here, is pending.
> +     */

GET CONFIGURATION is allowed as well. That would be an unrelated fix,
though, so we can do it on top.

Kevin

Re: [Qemu-devel] [PATCH v2 4/6] atapi: GESN: Use structs for commonly-used field types

[Kevin Wolf]

Am 12.04.2011 11:27, schrieb Amit Shah:
> Instead of using magic numbers, use structs that are more descriptive of
> the fields being used.
> 
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
>  hw/ide/core.c |   15 +++++++++++++--
>  1 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index c5913d8..fe50d8a 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -1097,12 +1097,23 @@ static void handle_get_event_status_notification(IDEState *s,
>                                                   uint8_t *buf,
>                                                   const uint8_t *packet)
>  {
> +    struct {
> +        uint8_t opcode;
> +        uint8_t polled;   /* lsb bit is polled; others are reserved */
> +        uint8_t reserved2[2];
> +        uint8_t request;

Maybe class would be a better name?

> +        uint8_t reserved3[2];
> +        uint8_t len_msb;
> +        uint8_t len_lsb;

Why not a uint16_t length?

> +        uint8_t control;
> +    } __attribute__((packed)) *gesn_cdb;
>      unsigned int max_len, used_len;
>  
> -    max_len = ube16_to_cpu(packet + 7);
> +    gesn_cdb = (void *)packet;
> +    max_len = ube16_to_cpu(&gesn_cdb->len_msb);

Instead of reading 16 bit from a 8 bit pointer, you could then use
be16_to_cpu(gesn_cdb->length);

>  
>      /* It is fine by the MMC spec to not support async mode operations */
> -    if (!(packet[1] & 0x01)) { /* asynchronous mode */
> +    if (!(gesn_cdb->polled & 0x01)) { /* asynchronous mode */
>          /* Only polling is supported, asynchronous mode is not. */
>          ide_atapi_cmd_error(s, SENSE_ILLEGAL_REQUEST,
>                              ASC_INV_FIELD_IN_CMD_PACKET);

Kevin

Re: [Qemu-devel] [PATCH v2 5/6] atapi: GESN: implement 'media' subcommand

[Kevin Wolf]

Am 12.04.2011 11:27, schrieb Amit Shah:
> Implement the 'media' sub-command of the GET_EVENT_STATUS_NOTIFICATION
> command.  This helps us report tray open, tray closed, no media, media
> present states to the guest.
> 
> Newer Linux kernels (2.6.38+) rely on this command to revalidate discs
> after media change.
> 
> This patch also sends out tray open/closed status to the guest driver
> when requested e.g. via the CDROM_DRIVE_STATUS ioctl (thanks Markus).
> Without such notification, the guest and qemu's tray open/close status
> was frequently out of sync, causing installers like Anaconda detecting
> no disc instead of tray open, confusing them terribly.
> 
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
>  hw/ide/core.c     |   92 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>  hw/ide/internal.h |    6 +++
>  2 files changed, 96 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index fe50d8a..2683070 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -1084,6 +1084,47 @@ static int ide_dvd_read_structure(IDEState *s, int format,
>      }
>  }
>  
> +static unsigned int event_status_media(IDEState *s,
> +                                       uint8_t *buf,
> +                                       unsigned int max_len,
> +                                       unsigned int event_class,
> +                                       unsigned int supported_events)
> +{
> +    enum media_event_code {
> +        no_change = 0,       /* Status unchanged */
> +        eject_requested,     /* received a request from user to eject */
> +        new_media,           /* new media inserted and ready for access */
> +        media_removal,       /* only for media changers */
> +        media_changed,       /* only for media changers */
> +        bg_format_completed, /* MRW or DVD+RW b/g format completed */
> +        bg_format_restarted, /* MRW or DVD+RW b/g format restarted */
> +    };
> +    enum media_status {
> +        tray_open = 1,
> +        media_present = 2,
> +    };
> +    uint8_t event_code, media_status;
> +
> +    media_status = 0;
> +    if (s->bs->tray_open) {
> +        media_status = tray_open;
> +    } else if (bdrv_is_inserted(s->bs)) {
> +        media_status = media_present;
> +    }
> +
> +    /* Event notification descriptor */
> +    event_code = no_change;
> +    if (media_status != tray_open && s->events.new_media) {
> +        event_code = new_media;
> +        s->events.new_media = false;
> +    }
> +
> +    buf[4] = event_code;
> +    buf[5] = media_status;
> +
> +    return 6; /* We wrote to just 2 extra bytes from the header */

I must admit that I don't understand your answer you gave on v1 here.
Let me quote:

>> > After media_state, there are two more fields for start/end slot (even
>> > though they are reserved because we don't have a multiple slot device)
> Yes, they're reserved, so we shouldn't change them.  Any change might
> trigger bad response from guests.

I'm not sure what we would be _changing_. We're building a response
structure here, not modifying existing data.

So what your code does is to receive a short response that leaves out
the reserved fields. I don't think this is how it's supposed to work. We
should include the reserved fields in the descriptor length and zero
them (MMC-5, section 3.6.8):

"“Reserved” is a keyword referring to bits, bytes, words, fields and
code values that are set aside for future standardization. A reserved
bit, byte, word or field shall be set to zero, or in accordance with a
future extension to this standard."

> +}
> +
>  static unsigned int event_status_nea(uint8_t *buf, unsigned int max_len)
>  {
>      cpu_to_ube16(buf, 0x00); /* No event descriptor returned */
> @@ -1107,7 +1148,28 @@ static void handle_get_event_status_notification(IDEState *s,
>          uint8_t len_lsb;
>          uint8_t control;
>      } __attribute__((packed)) *gesn_cdb;
> +    enum notification_class_request_type {
> +        reserved1 = 1 << 0,
> +        operational_change = 1 << 1,
> +        power_management = 1 << 2,
> +        external_request = 1 << 3,
> +        media = 1 << 4,
> +        multi_host = 1 << 5,
> +        device_busy = 1 << 6,
> +        reserved2 = 1 << 7,
> +    };
> +    enum event_notification_class_field {
> +        enc_no_events = 0,
> +        enc_operational_change,
> +        enc_power_management,
> +        enc_external_request,
> +        enc_media,
> +        enc_multiple_hosts,
> +        enc_device_busy,
> +        enc_reserved,
> +    };
>      unsigned int max_len, used_len;
> +    unsigned int supported_events;
>  
>      gesn_cdb = (void *)packet;
>      max_len = ube16_to_cpu(&gesn_cdb->len_msb);
> @@ -1122,8 +1184,33 @@ static void handle_get_event_status_notification(IDEState *s,
>  
>      /* polling mode operation */
>  
> -    /* We don't support any event class (yet). */
> -    used_len = event_status_nea(buf, max_len);
> +    /*
> +     * These are the supported events.
> +     *
> +     * We currently only support requests of the 'media' type.
> +     */
> +    supported_events = media;
> +
> +    /*
> +     * Event notification header; will be overwritten by the
> +     * NO_EVENT_AVAILABLE code if we don't have events: according to
> +     * MMC-5 6.7.2.2, if nea = 1, event class field should be 0.
> +     */
> +    cpu_to_ube16(buf, max_len);

That doesn't look right. I think it needs to be used_len - sizeof(header).

> +    buf[2] = event_class;
> +    buf[3] = supported_events;

The spec doesn't talk about "event class" for buf[2], but about
"notification class" (same applies for the comment above).  We should
stick to that as buf[3] is called "supported event class", so they might
be confused.

> +
> +    /*
> +     * Responses to requests are to be based on request priority.  The
> +     * notification_class_request_type enum above specifies the
> +     * priority: upper elements are higher prio than lower ones.
> +     */
> +    if (gesn_cdb->request & media) {
> +        used_len = event_status_media(s, buf, max_len, enc_media,
> +                                      supported_events);
> +    } else {
> +        used_len = event_status_nea(buf, max_len);

This expands to:

    cpu_to_ube16(buf, 0x00); /* No event descriptor returned */
    buf[2] = 0x80;           /* No Event Available (NEA) */
    buf[3] = 0x00;           /* Empty supported event classes */

The first one is covered if you fix what I mentioned above (used_len -
sizeof(header)). The third one is wrong, we still support the media
class. So what is left is one line:

    buf[2] = 0x80;           /* No Event Available (NEA) */

I'm still not convinced that having event_status_nea() as a separate
function makes a lot of sense.

> +    }
>      ide_atapi_cmd_reply(s, used_len, max_len);
>  }
>  
> @@ -1650,6 +1737,7 @@ 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->events.new_media = true;
>      ide_set_irq(s->bus);
>  }
>  
> diff --git a/hw/ide/internal.h b/hw/ide/internal.h
> index d533fb6..ba7e9a8 100644
> --- a/hw/ide/internal.h
> +++ b/hw/ide/internal.h
> @@ -373,6 +373,11 @@ typedef int DMAFunc(IDEDMA *);
>  typedef int DMAIntFunc(IDEDMA *, int);
>  typedef void DMARestartFunc(void *, int, int);
>  
> +struct unreported_events {
> +    bool eject_request;
> +    bool new_media;
> +};
> +
>  /* NOTE: IDEState represents in fact one drive */
>  struct IDEState {
>      IDEBus *bus;
> @@ -408,6 +413,7 @@ struct IDEState {
>      BlockDriverState *bs;
>      char version[9];
>      /* ATAPI specific */
> +    struct unreported_events events;
>      uint8_t sense_key;
>      uint8_t asc;
>      uint8_t cdrom_changed;

Kevin

Re: [Qemu-devel] [PATCH v2 6/6] atapi: Save / load the new GESN event states during migration

[Kevin Wolf]

Am 12.04.2011 11:27, schrieb Amit Shah:
> Add a new subsection to save and restore the events state for the
> GET_EVENT_STATUS_NOTIFICATION command.
> 
> Signed-off-by: Amit Shah <amit.shah@redhat.com>

Looks good, but I think it should be merged into patch 5, so that there
are no commits for which migration is broken.

Kevin