[Qemu-devel] [PATCH v5 3/8] fw_cfg: add vmcoreinfo file

[Marc-André Lureau]

See docs/specs/fw_cfg.txt for details.

The "etc/vmcoreinfo" is added when using "-global
fw_cfg.vmcoreinfo=on" qemu option.

Disabled by default for machine types v2.9 and older.

Signed-off-by: Marc-André Lureau <address@hidden>
---
 include/hw/compat.h       |  8 ++++++++
 include/hw/nvram/fw_cfg.h |  9 +++++++++
 hw/nvram/fw_cfg.c         | 20 ++++++++++++++++++++
 docs/specs/fw_cfg.txt     | 16 ++++++++++++++++
 4 files changed, 53 insertions(+)

diff --git a/include/hw/compat.h b/include/hw/compat.h
index 08f36004da..317fd2e2e3 100644
--- a/include/hw/compat.h
+++ b/include/hw/compat.h
@@ -18,6 +18,14 @@
         .driver   = "pcie-root-port",\
         .property = "x-migrate-msix",\
         .value    = "false",\
+    },{\
+        .driver   = "fw_cfg_mem",\
+        .property = "vmcoreinfo",\
+        .value    = "off",\
+    },{\
+        .driver   = "fw_cfg_io",\
+        .property = "vmcoreinfo",\
+        .value    = "off",\
     },
 
 #define HW_COMPAT_2_8 \
diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index 3527cd51d8..a35f47405d 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -30,6 +30,11 @@ typedef struct FWCfgFile {
 void fw_cfg_set_order_override(FWCfgState *fw_cfg, int order);
 void fw_cfg_reset_order_override(FWCfgState *fw_cfg);
 
+typedef struct FWCfgVMCoreInfo {
+    uint64_t paddr;
+    uint32_t size;
+} QEMU_PACKED FWCfgVMCoreInfo;
+
 typedef struct FWCfgFiles {
     uint32_t  count;
     FWCfgFile f[];
@@ -65,6 +70,10 @@ struct FWCfgState {
     dma_addr_t dma_addr;
     AddressSpace *dma_as;
     MemoryRegion dma_iomem;
+
+    bool vmcoreinfo_enabled;
+    bool has_vmcoreinfo;
+    FWCfgVMCoreInfo vmcoreinfo;
 };
 
 struct FWCfgIoState {
diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 28780088b9..342afc4ed2 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -504,6 +504,7 @@ static void fw_cfg_reset(DeviceState *d)
 
     /* we never register a read callback for FW_CFG_SIGNATURE */
     fw_cfg_select(s, FW_CFG_SIGNATURE);
+    s->has_vmcoreinfo = false;
 }
 
 /* Save restore 32 bit int as uint16_t
@@ -869,7 +870,12 @@ static void fw_cfg_machine_ready(struct Notifier *n, void 
*data)
     qemu_register_reset(fw_cfg_machine_reset, s);
 }
 
+static void fw_cfg_vmci_written(void *dev)
+{
+    FWCfgState *s = FW_CFG(dev);
 
+    s->has_vmcoreinfo = true;
+}
 
 static void fw_cfg_common_realize(DeviceState *dev, Error **errp)
 {
@@ -895,6 +901,16 @@ static void fw_cfg_common_realize(DeviceState *dev, Error 
**errp)
 
     fw_cfg_add_i32(s, FW_CFG_ID, version);
 
+    if (s->vmcoreinfo_enabled) {
+        if (!s->dma_enabled) {
+            error_setg(errp, "vmcoreinfo requires dma_enabled");
+            return;
+        }
+        fw_cfg_add_file_callback(s, "etc/vmcoreinfo",
+                                 NULL, fw_cfg_vmci_written, s,
+                                 &s->vmcoreinfo, sizeof(s->vmcoreinfo), false);
+    }
+
     s->machine_ready.notify = fw_cfg_machine_ready;
     qemu_add_machine_init_done_notifier(&s->machine_ready);
 }
@@ -1031,6 +1047,8 @@ static void fw_cfg_file_slots_allocate(FWCfgState *s, 
Error **errp)
 static Property fw_cfg_io_properties[] = {
     DEFINE_PROP_BOOL("dma_enabled", FWCfgIoState, parent_obj.dma_enabled,
                      true),
+    DEFINE_PROP_BOOL("vmcoreinfo", FWCfgIoState, parent_obj.vmcoreinfo_enabled,
+                     true),
     DEFINE_PROP_UINT16("x-file-slots", FWCfgIoState, parent_obj.file_slots,
                        FW_CFG_FILE_SLOTS_DFLT),
     DEFINE_PROP_END_OF_LIST(),
@@ -1082,6 +1100,8 @@ static Property fw_cfg_mem_properties[] = {
     DEFINE_PROP_UINT32("data_width", FWCfgMemState, data_width, -1),
     DEFINE_PROP_BOOL("dma_enabled", FWCfgMemState, parent_obj.dma_enabled,
                      true),
+    DEFINE_PROP_BOOL("vmcoreinfo", FWCfgMemState, 
parent_obj.vmcoreinfo_enabled,
+                     true),
     DEFINE_PROP_UINT16("x-file-slots", FWCfgMemState, parent_obj.file_slots,
                        FW_CFG_FILE_SLOTS_DFLT),
     DEFINE_PROP_END_OF_LIST(),
diff --git a/docs/specs/fw_cfg.txt b/docs/specs/fw_cfg.txt
index 08c00bdf44..37d0f9f40a 100644
--- a/docs/specs/fw_cfg.txt
+++ b/docs/specs/fw_cfg.txt
@@ -136,6 +136,22 @@ struct FWCfgFile {         /* an individual file entry, 64 
bytes total */
     char name[56];             /* fw_cfg item name, NUL-terminated ascii */
 };
 
+=== etc/vmcoreinfo ===
+
+A guest may use this entry to add information details to qemu
+dumps. The entry gives location and size of an ELF note that is
+appended in qemu dumps.
+
+The entry is of 12 bytes with this format:
+
+struct FWCfgVMCoreInfo {
+    uint64_t paddr;             /* physical address of ELF note, LE */
+    uint32_t size;              /* size of ELF note region, LE */
+};
+
+The note format/class must be of the target bitness and the size must
+be less than 1Mb.
+
 === All Other Data Items ===
 
 Please consult the QEMU source for the most up-to-date and authoritative list
-- 
2.14.0.1.geff633fa0