[Qemu-devel] [RFC PATCH 10/17] ide/scsi: add discard_zeroes_data property

[Paolo Bonzini <pbonzini@redhat.com>]

Now that the block layer guarantees stable semantics for discard,
we can expose them to guests.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block.h        |    7 +++++--
 hw/ide/core.c  |    6 +++++-
 hw/scsi-disk.c |    5 ++++-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/block.h b/block.h
index ef07bb0..e28321e 100644
--- a/block.h
+++ b/block.h
@@ -423,6 +423,7 @@ typedef struct BlockConf {
     uint32_t opt_io_size;
     int32_t bootindex;
     uint32_t discard_granularity;
+    uint32_t discard_zeroes_data;
 } BlockConf;
 
 static inline unsigned int get_physical_block_exp(BlockConf *conf)
@@ -444,10 +445,12 @@ static inline unsigned int get_physical_block_exp(BlockConf *conf)
                        _conf.logical_block_size, 512),                  \
     DEFINE_PROP_UINT16("physical_block_size", _state,                   \
                        _conf.physical_block_size, 512),                 \
-    DEFINE_PROP_UINT16("min_io_size", _state, _conf.min_io_size, 0),  \
+    DEFINE_PROP_UINT16("min_io_size", _state, _conf.min_io_size, 0),    \
     DEFINE_PROP_UINT32("opt_io_size", _state, _conf.opt_io_size, 0),    \
     DEFINE_PROP_INT32("bootindex", _state, _conf.bootindex, -1),        \
-    DEFINE_PROP_UINT32("discard_granularity", _state, \
+    DEFINE_PROP_BIT("discard_zeroes_data", _state,                      \
+                    _conf.discard_zeroes_data, 0, false),               \
+    DEFINE_PROP_UINT32("discard_granularity", _state,                   \
                        _conf.discard_granularity, 0)
 
 #endif
diff --git a/hw/ide/core.c b/hw/ide/core.c
index f12470e..1530b61 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -128,7 +128,11 @@ static void ide_identify(IDEState *s)
     put_le16(p + 67, 120);
     put_le16(p + 68, 120);
     if (dev && dev->conf.discard_granularity) {
-        put_le16(p + 69, (1 << 14)); /* determinate TRIM behavior */
+        int val;
+
+        val = 0x4000;
+        val |= dev->conf.discard_zeroes_data ? 0x20 : 0;
+        put_le16(p + 69, val); /* determinate TRIM behavior */
     }
 
     if (s->ncq_queues) {
diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index add399e..f489078 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -1295,8 +1295,11 @@ static int scsi_disk_emulate_command(SCSIDiskReq *r)
             outbuf[13] = get_physical_block_exp(&s->qdev.conf);
 
             /* set TPE bit if the format supports discard */
-            if (s->qdev.conf.discard_granularity) {
+            if (s->qdev.type == TYPE_DISK && s->qdev.conf.discard_granularity) {
                 outbuf[14] = 0x80;
+                if (s->qdev.conf.discard_zeroes_data) {
+                    outbuf[14] |= 0x40;
+                }
             }
 
             /* Protection, exponent and lowest lba field left blank. */
-- 
1.7.7.6