[Qemu-devel] [PATCH v4 1/3] nvdimm acpi: introduce fit buffer

[Xiao Guangrong]

The buffer is used to save the FIT info for all the presented nvdimm
devices which is updated after the nvdimm device is plugged or
unplugged. In the later patch, it will be used to construct NVDIMM
ACPI _FIT method which reflects the presented nvdimm devices after
nvdimm hotplug

As FIT buffer can not completely mapped into guest address space,
OSPM will exit to QEMU multiple times, however, there is the race
condition - FIT may be changed during these multiple exits, so that
we mark @dirty whenever the buffer is updated.

@dirty is cleared for the first time OSPM gets fit buffer, if
dirty is detected in the later access, OSPM will restart the
access

Signed-off-by: Xiao Guangrong <address@hidden>
---
 hw/acpi/nvdimm.c        | 57 ++++++++++++++++++++++++++++++-------------------
 hw/i386/acpi-build.c    |  2 +-
 hw/i386/pc.c            |  4 ++++
 include/hw/mem/nvdimm.h | 21 +++++++++++++++++-
 4 files changed, 60 insertions(+), 24 deletions(-)

diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
index b8a2e62..9fee077 100644
--- a/hw/acpi/nvdimm.c
+++ b/hw/acpi/nvdimm.c
@@ -38,11 +38,7 @@ static int nvdimm_plugged_device_list(Object *obj, void 
*opaque)
     GSList **list = opaque;
 
     if (object_dynamic_cast(obj, TYPE_NVDIMM)) {
-        DeviceState *dev = DEVICE(obj);
-
-        if (dev->realized) { /* only realized NVDIMMs matter */
-            *list = g_slist_append(*list, DEVICE(obj));
-        }
+        *list = g_slist_append(*list, DEVICE(obj));
     }
 
     object_child_foreach(obj, nvdimm_plugged_device_list, opaque);
@@ -348,8 +344,9 @@ static void nvdimm_build_structure_dcr(GArray *structures, 
DeviceState *dev)
                                          (DSM) in DSM Spec Rev1.*/);
 }
 
-static GArray *nvdimm_build_device_structure(GSList *device_list)
+static GArray *nvdimm_build_device_structure(void)
 {
+    GSList *device_list = nvdimm_get_plugged_device_list();
     GArray *structures = g_array_new(false, true /* clear */, 1);
 
     for (; device_list; device_list = device_list->next) {
@@ -367,28 +364,50 @@ static GArray *nvdimm_build_device_structure(GSList 
*device_list)
         /* build NVDIMM Control Region Structure. */
         nvdimm_build_structure_dcr(structures, dev);
     }
+    g_slist_free(device_list);
 
     return structures;
 }
 
-static void nvdimm_build_nfit(GSList *device_list, GArray *table_offsets,
+static void nvdimm_init_fit_buffer(NvdimmFitBuffer *fit_buf)
+{
+    fit_buf->fit = g_array_new(false, true /* clear */, 1);
+}
+
+static void nvdimm_build_fit_buffer(NvdimmFitBuffer *fit_buf)
+{
+    g_array_free(fit_buf->fit, true);
+    fit_buf->fit = nvdimm_build_device_structure();
+    fit_buf->dirty = true;
+}
+
+void nvdimm_acpi_hotplug(AcpiNVDIMMState *state)
+{
+    nvdimm_build_fit_buffer(&state->fit_buf);
+}
+
+static void nvdimm_build_nfit(AcpiNVDIMMState *state, GArray *table_offsets,
                               GArray *table_data, BIOSLinker *linker)
 {
-    GArray *structures = nvdimm_build_device_structure(device_list);
+    NvdimmFitBuffer *fit_buf = &state->fit_buf;
     unsigned int header;
 
+    /* NVDIMM device is not plugged? */
+    if (!fit_buf->fit->len) {
+        return;
+    }
+
     acpi_add_table(table_offsets, table_data);
 
     /* NFIT header. */
     header = table_data->len;
     acpi_data_push(table_data, sizeof(NvdimmNfitHeader));
     /* NVDIMM device structures. */
-    g_array_append_vals(table_data, structures->data, structures->len);
+    g_array_append_vals(table_data, fit_buf->fit->data, fit_buf->fit->len);
 
     build_header(linker, table_data,
                  (void *)(table_data->data + header), "NFIT",
-                 sizeof(NvdimmNfitHeader) + structures->len, 1, NULL, NULL);
-    g_array_free(structures, true);
+                 sizeof(NvdimmNfitHeader) + fit_buf->fit->len, 1, NULL, NULL);
 }
 
 struct NvdimmDsmIn {
@@ -771,6 +790,8 @@ void nvdimm_init_acpi_state(AcpiNVDIMMState *state, 
MemoryRegion *io,
     acpi_data_push(state->dsm_mem, sizeof(NvdimmDsmIn));
     fw_cfg_add_file(fw_cfg, NVDIMM_DSM_MEM_FILE, state->dsm_mem->data,
                     state->dsm_mem->len);
+
+    nvdimm_init_fit_buffer(&state->fit_buf);
 }
 
 #define NVDIMM_COMMON_DSM       "NCAL"
@@ -1045,25 +1066,17 @@ static void nvdimm_build_ssdt(GArray *table_offsets, 
GArray *table_data,
 }
 
 void nvdimm_build_acpi(GArray *table_offsets, GArray *table_data,
-                       BIOSLinker *linker, GArray *dsm_dma_arrea,
+                       BIOSLinker *linker, AcpiNVDIMMState *state,
                        uint32_t ram_slots)
 {
-    GSList *device_list;
-
-    device_list = nvdimm_get_plugged_device_list();
-
-    /* NVDIMM device is plugged. */
-    if (device_list) {
-        nvdimm_build_nfit(device_list, table_offsets, table_data, linker);
-        g_slist_free(device_list);
-    }
+    nvdimm_build_nfit(state, table_offsets, table_data, linker);
 
     /*
      * NVDIMM device is allowed to be plugged only if there is available
      * slot.
      */
     if (ram_slots) {
-        nvdimm_build_ssdt(table_offsets, table_data, linker, dsm_dma_arrea,
+        nvdimm_build_ssdt(table_offsets, table_data, linker, state->dsm_mem,
                           ram_slots);
     }
 }
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 6ae4769..bc49958 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -2767,7 +2767,7 @@ void acpi_build(AcpiBuildTables *tables, MachineState 
*machine)
     }
     if (pcms->acpi_nvdimm_state.is_enabled) {
         nvdimm_build_acpi(table_offsets, tables_blob, tables->linker,
-                          pcms->acpi_nvdimm_state.dsm_mem, machine->ram_slots);
+                          &pcms->acpi_nvdimm_state, machine->ram_slots);
     }
 
     /* Add tables supplied by user (if any) */
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 93ff49c..77ca7f4 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1700,6 +1700,10 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
         goto out;
     }
 
+    if (object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM)) {
+        nvdimm_acpi_hotplug(&pcms->acpi_nvdimm_state);
+    }
+
     hhc = HOTPLUG_HANDLER_GET_CLASS(pcms->acpi_dev);
     hhc->plug(HOTPLUG_HANDLER(pcms->acpi_dev), dev, &error_abort);
 out:
diff --git a/include/hw/mem/nvdimm.h b/include/hw/mem/nvdimm.h
index 63a2b20..232437c 100644
--- a/include/hw/mem/nvdimm.h
+++ b/include/hw/mem/nvdimm.h
@@ -98,12 +98,30 @@ typedef struct NVDIMMClass NVDIMMClass;
 #define NVDIMM_ACPI_IO_BASE     0x0a18
 #define NVDIMM_ACPI_IO_LEN      4
 
+/*
+ * The buffer, @fit, saves the FIT info for all the presented NVDIMM
+ * devices which is updated after the NVDIMM device is plugged or
+ * unplugged.
+ *
+ * Mark @dirty whenever the buffer is updated so that it preserves NVDIMM
+ * ACPI _FIT method to read incomplete or obsolete fit info if fit update
+ * happens during multiple RFIT calls.
+ */
+struct NvdimmFitBuffer {
+    GArray *fit;
+    bool dirty;
+};
+typedef struct NvdimmFitBuffer NvdimmFitBuffer;
+
 struct AcpiNVDIMMState {
     /* detect if NVDIMM support is enabled. */
     bool is_enabled;
 
     /* the data of the fw_cfg file NVDIMM_DSM_MEM_FILE. */
     GArray *dsm_mem;
+
+    NvdimmFitBuffer fit_buf;
+
     /* the IO region used by OSPM to transfer control to QEMU. */
     MemoryRegion io_mr;
 };
@@ -112,6 +130,7 @@ typedef struct AcpiNVDIMMState AcpiNVDIMMState;
 void nvdimm_init_acpi_state(AcpiNVDIMMState *state, MemoryRegion *io,
                             FWCfgState *fw_cfg, Object *owner);
 void nvdimm_build_acpi(GArray *table_offsets, GArray *table_data,
-                       BIOSLinker *linker, GArray *dsm_dma_arrea,
+                       BIOSLinker *linker, AcpiNVDIMMState *state,
                        uint32_t ram_slots);
+void nvdimm_acpi_hotplug(AcpiNVDIMMState *state);
 #endif
-- 
1.8.3.1