[v6,1/1] s390x/sclp: extend SCLP event masks to 64 bits

Commit Message

Claudio Imbrenda March 8, 2018, 11:04 a.m. UTC

Extend the SCLP event masks to 64 bits.

Notice that using any of the new bits results in a state that cannot be
migrated to an older version.

Signed-off-by: Claudio Imbrenda <[e-mail]>
---
 hw/s390x/event-facility.c         | 50 ++++++++++++++++++++++++++++++++-------
 include/hw/s390x/event-facility.h |  2 +-
 2 files changed, 42 insertions(+), 10 deletions(-)

Comments

Cornelia Huck March 8, 2018, 5:58 p.m. UTC | #1

On Thu,  8 Mar 2018 12:04:29 +0100
Claudio Imbrenda <[e-mail]> wrote:

> Extend the SCLP event masks to 64 bits.
> 
> Notice that using any of the new bits results in a state that cannot be
> migrated to an older version.
> 
> Signed-off-by: Claudio Imbrenda <[e-mail]>
> ---
>  hw/s390x/event-facility.c         | 50 ++++++++++++++++++++++++++++++++-------
>  include/hw/s390x/event-facility.h |  2 +-
>  2 files changed, 42 insertions(+), 10 deletions(-)

While this looks sane to me at a quick look, I did not have the
resources to properly handle this before softfreeze (I'm off after
tomorrow), sorry.

If any of the other maintainers wants to queue this next week, no
objections from me.

Cornelia Huck April 5, 2018, 12:24 p.m. UTC | #2

On Thu,  8 Mar 2018 12:04:29 +0100
Claudio Imbrenda <[e-mail]> wrote:

> Extend the SCLP event masks to 64 bits.
> 
> Notice that using any of the new bits results in a state that cannot be
> migrated to an older version.
> 
> Signed-off-by: Claudio Imbrenda <[e-mail]>
> ---
>  hw/s390x/event-facility.c         | 50 ++++++++++++++++++++++++++++++++-------
>  include/hw/s390x/event-facility.h |  2 +-
>  2 files changed, 42 insertions(+), 10 deletions(-)

Thanks, applied.

Patch

diff --git a/hw/s390x/event-facility.c b/hw/s390x/event-facility.c
index e04ed9f..773f104 100644
--- a/hw/s390x/event-facility.c
+++ b/hw/s390x/event-facility.c
@@ -26,11 +26,23 @@  typedef struct SCLPEventsBus {
     BusState qbus;
 } SCLPEventsBus;
 
+/* we need to save 32 bit chunks for compatibility */
+#ifdef HOST_WORDS_BIGENDIAN
+#define RECV_MASK_LOWER 1
+#define RECV_MASK_UPPER 0
+#else /* little endian host */
+#define RECV_MASK_LOWER 0
+#define RECV_MASK_UPPER 1
+#endif
+
 struct SCLPEventFacility {
     SysBusDevice parent_obj;
     SCLPEventsBus sbus;
     /* guest's receive mask */
-    sccb_mask_t receive_mask;
+    union {
+        uint32_t receive_mask_pieces[2];
+        sccb_mask_t receive_mask;
+    };
     /*
      * when false, we keep the same broken, backwards compatible behaviour as
      * before, allowing only masks of size exactly 4; when true, we implement
@@ -262,7 +274,7 @@  static void read_event_data(SCLPEventFacility *ef, SCCB *sccb)
     case SCLP_SELECTIVE_READ:
         copy_mask((uint8_t *)&sclp_active_selection_mask, (uint8_t *)&red->mask,
                   sizeof(sclp_active_selection_mask), ef->mask_length);
-        sclp_active_selection_mask = be32_to_cpu(sclp_active_selection_mask);
+        sclp_active_selection_mask = be64_to_cpu(sclp_active_selection_mask);
         if (!sclp_cp_receive_mask ||
             (sclp_active_selection_mask & ~sclp_cp_receive_mask)) {
             sccb->h.response_code =
@@ -294,21 +306,22 @@  static void write_event_mask(SCLPEventFacility *ef, SCCB *sccb)
     }
 
     /*
-     * Note: We currently only support masks up to 4 byte length;
-     *       the remainder is filled up with zeroes. Linux uses
-     *       a 4 byte mask length.
+     * Note: We currently only support masks up to 8 byte length;
+     *       the remainder is filled up with zeroes. Older Linux
+     *       kernels use a 4 byte mask length, newer ones can use both
+     *       8 or 4 depending on what is available on the host.
      */
 
     /* keep track of the guest's capability masks */
     copy_mask((uint8_t *)&tmp_mask, WEM_CP_RECEIVE_MASK(we_mask, mask_length),
               sizeof(tmp_mask), mask_length);
-    ef->receive_mask = be32_to_cpu(tmp_mask);
+    ef->receive_mask = be64_to_cpu(tmp_mask);
 
     /* return the SCLP's capability masks to the guest */
-    tmp_mask = cpu_to_be32(get_host_receive_mask(ef));
+    tmp_mask = cpu_to_be64(get_host_receive_mask(ef));
     copy_mask(WEM_RECEIVE_MASK(we_mask, mask_length), (uint8_t *)&tmp_mask,
               mask_length, sizeof(tmp_mask));
-    tmp_mask = cpu_to_be32(get_host_send_mask(ef));
+    tmp_mask = cpu_to_be64(get_host_send_mask(ef));
     copy_mask(WEM_SEND_MASK(we_mask, mask_length), (uint8_t *)&tmp_mask,
               mask_length, sizeof(tmp_mask));
 
@@ -369,6 +382,13 @@  static void command_handler(SCLPEventFacility *ef, SCCB *sccb, uint64_t code)
     }
 }
 
+static bool vmstate_event_facility_mask64_needed(void *opaque)
+{
+    SCLPEventFacility *ef = opaque;
+
+    return (ef->receive_mask & 0xFFFFFFFF) != 0;
+}
+
 static bool vmstate_event_facility_mask_length_needed(void *opaque)
 {
     SCLPEventFacility *ef = opaque;
@@ -376,6 +396,17 @@  static bool vmstate_event_facility_mask_length_needed(void *opaque)
     return ef->allow_all_mask_sizes;
 }
 
+static const VMStateDescription vmstate_event_facility_mask64 = {
+    .name = "vmstate-event-facility/mask64",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .needed = vmstate_event_facility_mask64_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(receive_mask_pieces[RECV_MASK_LOWER], SCLPEventFacility),
+        VMSTATE_END_OF_LIST()
+     }
+};
+
 static const VMStateDescription vmstate_event_facility_mask_length = {
     .name = "vmstate-event-facility/mask_length",
     .version_id = 0,
@@ -392,10 +423,11 @@  static const VMStateDescription vmstate_event_facility = {
     .version_id = 0,
     .minimum_version_id = 0,
     .fields = (VMStateField[]) {
-        VMSTATE_UINT32(receive_mask, SCLPEventFacility),
+        VMSTATE_UINT32(receive_mask_pieces[RECV_MASK_UPPER], SCLPEventFacility),
         VMSTATE_END_OF_LIST()
      },
     .subsections = (const VMStateDescription * []) {
+        &vmstate_event_facility_mask64,
         &vmstate_event_facility_mask_length,
         NULL
      }
diff --git a/include/hw/s390x/event-facility.h b/include/hw/s390x/event-facility.h
index 0e2b761..06ba4ea 100644
--- a/include/hw/s390x/event-facility.h
+++ b/include/hw/s390x/event-facility.h
@@ -73,7 +73,7 @@  typedef struct WriteEventMask {
 #define WEM_RECEIVE_MASK(wem, mask_len) ((wem)->masks + 2 * (mask_len))
 #define WEM_SEND_MASK(wem, mask_len) ((wem)->masks + 3 * (mask_len))
 
-typedef uint32_t sccb_mask_t;
+typedef uint64_t sccb_mask_t;
 
 typedef struct EventBufferHeader {
     uint16_t length;