fw_cfg: add write callback

Reintroduce the write callback that was removed when write support was
removed in commit 023e3148.

Contrary to the previous callback implementation, the write_cb
callback is called whenever a write happened, so handlers must be
ready to handle partial write as necessary.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/acpi/vmgenid.c

@@ -124,7 +124,7 @@ void vmgenid_add_fw_cfg(VmGenIdState *vms, FWCfgState *s, GArray *guid)
     fw_cfg_add_file(s, VMGENID_GUID_FW_CFG_FILE, guid->data,
                     VMGENID_FW_CFG_SIZE);
     /* Create a read-write fw_cfg file for Address */
-    fw_cfg_add_file_callback(s, VMGENID_ADDR_FW_CFG_FILE, NULL, NULL,
+    fw_cfg_add_file_callback(s, VMGENID_ADDR_FW_CFG_FILE, NULL, NULL, NULL,
                              vms->vmgenid_addr_le,
                              ARRAY_SIZE(vms->vmgenid_addr_le), false);
 }

hw/core/loader.c

@@ -1023,7 +1023,7 @@ MemoryRegion *rom_add_blob(const char *name, const void *blob, size_t len,
         }
 
         fw_cfg_add_file_callback(fw_cfg, fw_file_name,
-                                 fw_callback, callback_opaque,
+                                 fw_callback, NULL, callback_opaque,
                                  data, rom->datasize, read_only);
     }
     return mr;

hw/i386/acpi-build.c

@@ -2911,7 +2911,7 @@ void acpi_setup(void)
 
         build_state->rsdp = g_memdup(tables.rsdp->data, rsdp_size);
         fw_cfg_add_file_callback(pcms->fw_cfg, ACPI_BUILD_RSDP_FILE,
-                                 acpi_build_update, build_state,
+                                 acpi_build_update, NULL, build_state,
                                  build_state->rsdp, rsdp_size, true);
         build_state->rsdp_mr = NULL;
     } else {

hw/isa/lpc_ich9.c

@@ -402,12 +402,12 @@ void ich9_lpc_pm_init(PCIDevice *lpc_pci, bool smm_enabled)
          * just link them into fw_cfg here.
          */
         fw_cfg_add_file_callback(fw_cfg, "etc/smi/requested-features",
-                                 NULL, NULL,
+                                 NULL, NULL, NULL,
                                  lpc->smi_guest_features_le,
                                  sizeof lpc->smi_guest_features_le,
                                  false);
         fw_cfg_add_file_callback(fw_cfg, "etc/smi/features-ok",
-                                 smi_features_ok_callback, lpc,
+                                 smi_features_ok_callback, NULL, lpc,
                                  &lpc->smi_features_ok,
                                  sizeof lpc->smi_features_ok,
                                  true);

hw/nvram/fw_cfg.c

@@ -56,6 +56,7 @@ struct FWCfgEntry {
     uint8_t *data;
     void *callback_opaque;
     FWCfgCallback select_cb;
+    FWCfgWriteCallback write_cb;
 };
 
 #define JPG_FILE 0
@@ -370,6 +371,8 @@ static void fw_cfg_dma_transfer(FWCfgState *s)
                     dma_memory_read(s->dma_as, dma.address,
                                     &e->data[s->cur_offset], len)) {
                     dma.control |= FW_CFG_DMA_CTL_ERROR;
+                } else if (e->write_cb) {
+                    e->write_cb(e->callback_opaque, s->cur_offset, len);
                 }
             }
 
@@ -570,6 +573,7 @@ static const VMStateDescription vmstate_fw_cfg = {
 
 static void fw_cfg_add_bytes_callback(FWCfgState *s, uint16_t key,
                                       FWCfgCallback select_cb,
+                                      FWCfgWriteCallback write_cb,
                                       void *callback_opaque,
                                       void *data, size_t len,
                                       bool read_only)
@@ -584,6 +588,7 @@ static void fw_cfg_add_bytes_callback(FWCfgState *s, uint16_t key,
     s->entries[arch][key].data = data;
     s->entries[arch][key].len = (uint32_t)len;
     s->entries[arch][key].select_cb = select_cb;
+    s->entries[arch][key].write_cb = write_cb;
     s->entries[arch][key].callback_opaque = callback_opaque;
     s->entries[arch][key].allow_write = !read_only;
 }
@@ -610,7 +615,7 @@ static void *fw_cfg_modify_bytes_read(FWCfgState *s, uint16_t key,
 
 void fw_cfg_add_bytes(FWCfgState *s, uint16_t key, void *data, size_t len)
 {
-    fw_cfg_add_bytes_callback(s, key, NULL, NULL, data, len, true);
+    fw_cfg_add_bytes_callback(s, key, NULL, NULL, NULL, data, len, true);
 }
 
 void fw_cfg_add_string(FWCfgState *s, uint16_t key, const char *value)
@@ -737,6 +742,7 @@ static int get_fw_cfg_order(FWCfgState *s, const char *name)
 
 void fw_cfg_add_file_callback(FWCfgState *s,  const char *filename,
                               FWCfgCallback select_cb,
+                              FWCfgWriteCallback write_cb,
                               void *callback_opaque,
                               void *data, size_t len, bool read_only)
 {
@@ -800,7 +806,7 @@ void fw_cfg_add_file_callback(FWCfgState *s,  const char *filename,
     }
 
     fw_cfg_add_bytes_callback(s, FW_CFG_FILE_FIRST + index,
-                              select_cb,
+                              select_cb, write_cb,
                               callback_opaque, data, len,
                               read_only);
 
@@ -815,7 +821,7 @@ void fw_cfg_add_file_callback(FWCfgState *s,  const char *filename,
 void fw_cfg_add_file(FWCfgState *s,  const char *filename,
                      void *data, size_t len)
 {
-    fw_cfg_add_file_callback(s, filename, NULL, NULL, data, len, true);
+    fw_cfg_add_file_callback(s, filename, NULL, NULL, NULL, data, len, true);
 }
 
 void *fw_cfg_modify_file(FWCfgState *s, const char *filename,
@@ -838,7 +844,7 @@ void *fw_cfg_modify_file(FWCfgState *s, const char *filename,
         }
     }
     /* add new one */
-    fw_cfg_add_file_callback(s, filename, NULL, NULL, data, len, true);
+    fw_cfg_add_file_callback(s, filename, NULL, NULL, NULL, data, len, true);
     return NULL;
 }
 

include/hw/nvram/fw_cfg.h

@@ -45,6 +45,7 @@ typedef struct FWCfgDmaAccess {
 } QEMU_PACKED FWCfgDmaAccess;
 
 typedef void (*FWCfgCallback)(void *opaque);
+typedef void (*FWCfgWriteCallback)(void *opaque, off_t start, size_t len);
 
 struct FWCfgState {
     /*< private >*/
@@ -183,6 +184,7 @@ void fw_cfg_add_file(FWCfgState *s, const char *filename, void *data,
  * @s: fw_cfg device being modified
  * @filename: name of new fw_cfg file item
  * @select_cb: callback function when selecting
+ * @write_cb: callback function after a write
  * @callback_opaque: argument to be passed into callback function
  * @data: pointer to start of item data
  * @len: size of item data
@@ -202,6 +204,7 @@ void fw_cfg_add_file(FWCfgState *s, const char *filename, void *data,
  */
 void fw_cfg_add_file_callback(FWCfgState *s, const char *filename,
                               FWCfgCallback select_cb,
+                              FWCfgWriteCallback write_cb,
                               void *callback_opaque,
                               void *data, size_t len, bool read_only);