[Qemu-devel] [PATCH v2 2/5] fw_cfg: remove support for guest-side data writes

["Gabriel L. Somlo" <somlo@cmu.edu>]

>From this point forward, any guest-side writes to the fw_cfg
data register will be treated as no-ops. This patch also removes
the unused host-side API function fw_cfg_add_callback(), which
allowed the registration of a callback to be executed each time
the guest completed a full overwrite of a given fw_cfg data item.

Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
---
 hw/nvram/fw_cfg.c         | 33 +--------------------------------
 include/hw/nvram/fw_cfg.h |  2 --
 trace-events              |  1 -
 3 files changed, 1 insertion(+), 35 deletions(-)

diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 78a37be..2f609b4 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -46,7 +46,6 @@ typedef struct FWCfgEntry {
     uint32_t len;
     uint8_t *data;
     void *callback_opaque;
-    FWCfgCallback callback;
     FWCfgReadCallback read_callback;
 } FWCfgEntry;
 
@@ -232,19 +231,7 @@ static void fw_cfg_reboot(FWCfgState *s)
 
 static void fw_cfg_write(FWCfgState *s, uint8_t value)
 {
-    int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
-    FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
-
-    trace_fw_cfg_write(s, value);
-
-    if (s->cur_entry & FW_CFG_WRITE_CHANNEL && e->callback &&
-        s->cur_offset < e->len) {
-        e->data[s->cur_offset++] = value;
-        if (s->cur_offset == e->len) {
-            e->callback(e->callback_opaque, e->data);
-            s->cur_offset = 0;
-        }
-    }
+    /* nothing, write support removed in QEMU v2.4+ */
 }
 
 static int fw_cfg_select(FWCfgState *s, uint16_t key)
@@ -458,7 +445,6 @@ static void *fw_cfg_modify_bytes_read(FWCfgState *s, uint16_t key,
     s->entries[arch][key].data = data;
     s->entries[arch][key].len = len;
     s->entries[arch][key].callback_opaque = NULL;
-    s->entries[arch][key].callback = NULL;
 
     return ptr;
 }
@@ -502,23 +488,6 @@ void fw_cfg_add_i64(FWCfgState *s, uint16_t key, uint64_t value)
     fw_cfg_add_bytes(s, key, copy, sizeof(value));
 }
 
-void fw_cfg_add_callback(FWCfgState *s, uint16_t key, FWCfgCallback callback,
-                         void *callback_opaque, void *data, size_t len)
-{
-    int arch = !!(key & FW_CFG_ARCH_LOCAL);
-
-    assert(key & FW_CFG_WRITE_CHANNEL);
-
-    key &= FW_CFG_ENTRY_MASK;
-
-    assert(key < FW_CFG_MAX_ENTRY && len <= UINT32_MAX);
-
-    s->entries[arch][key].data = data;
-    s->entries[arch][key].len = (uint32_t)len;
-    s->entries[arch][key].callback_opaque = callback_opaque;
-    s->entries[arch][key].callback = callback;
-}
-
 void fw_cfg_add_file_callback(FWCfgState *s,  const char *filename,
                               FWCfgReadCallback callback, void *callback_opaque,
                               void *data, size_t len)
diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index 6d8a8ac..b2e10c2 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -69,8 +69,6 @@ void fw_cfg_add_string(FWCfgState *s, uint16_t key, const char *value);
 void fw_cfg_add_i16(FWCfgState *s, uint16_t key, uint16_t value);
 void fw_cfg_add_i32(FWCfgState *s, uint16_t key, uint32_t value);
 void fw_cfg_add_i64(FWCfgState *s, uint16_t key, uint64_t value);
-void fw_cfg_add_callback(FWCfgState *s, uint16_t key, FWCfgCallback callback,
-                         void *callback_opaque, void *data, size_t len);
 void fw_cfg_add_file(FWCfgState *s, const char *filename, void *data,
                      size_t len);
 void fw_cfg_add_file_callback(FWCfgState *s, const char *filename,
diff --git a/trace-events b/trace-events
index 30eba92..1275b70 100644
--- a/trace-events
+++ b/trace-events
@@ -193,7 +193,6 @@ ecc_diag_mem_writeb(uint64_t addr, uint32_t val) "Write diagnostic %"PRId64" = %
 ecc_diag_mem_readb(uint64_t addr, uint32_t ret) "Read diagnostic %"PRId64"= %02x"
 
 # hw/nvram/fw_cfg.c
-fw_cfg_write(void *s, uint8_t value) "%p %d"
 fw_cfg_select(void *s, uint16_t key, int ret) "%p key %d = %d"
 fw_cfg_read(void *s, uint8_t ret) "%p = %d"
 fw_cfg_add_file_dupe(void *s, char *name) "%p %s"
-- 
2.1.0