[Qemu-devel] [PATCH 10/16] nvdimm: init the address region used by _DSM method

[Xiao Guangrong <guangrong.xiao@linux.intel.com>]

This memory range is used to transfer data between ACPI in guest and Qemu,
it occupies two pages:
- one is RAM-based used to save the input info of _DSM method and Qemu reuse
  it store output info

- another one is MMIO-based, ACPI write data to this page to transfer the
  control to Qemu

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
 hw/mem/pc-nvdimm.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 1 deletion(-)

diff --git a/hw/mem/pc-nvdimm.c b/hw/mem/pc-nvdimm.c
index e7cff29..4c290cb 100644
--- a/hw/mem/pc-nvdimm.c
+++ b/hw/mem/pc-nvdimm.c
@@ -37,6 +37,10 @@
 
 static struct nvdimms_info {
     ram_addr_t current_addr;
+
+    ram_addr_t dsm_addr;
+    int dsm_size;
+
     int device_index;
 } nvdimms_info;
 
@@ -324,14 +328,88 @@ static void build_nfit_table(GSList *device_list, char *buf)
     }
 }
 
+struct dsm_buffer {
+    /* RAM page. */
+    uint32_t handle;
+    uint8_t arg0[16];
+    uint32_t arg1;
+    uint32_t arg2;
+    union {
+        char arg3[PAGE_SIZE - 3 * sizeof(uint32_t) - 16 * sizeof(uint8_t)];
+    };
+
+    /* MMIO page. */
+    union {
+        uint32_t notify;
+        char pedding[PAGE_SIZE];
+    };
+};
+
+static uint64_t dsm_read(void *opaque, hwaddr addr,
+                         unsigned size)
+{
+    return 0;
+}
+
+static void dsm_write(void *opaque, hwaddr addr,
+                      uint64_t val, unsigned size)
+{
+}
+
+static const MemoryRegionOps dsm_ops = {
+    .read = dsm_read,
+    .write = dsm_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+};
+
+static int build_dsm_buffer(void)
+{
+    MemoryRegion *dsm_ram_mr, *dsm_mmio_mr;
+    ram_addr_t addr;;
+
+    QEMU_BUILD_BUG_ON(PAGE_SIZE * 2 != sizeof(struct dsm_buffer));
+
+    /* DSM buffer has already been built. */
+    if (nvdimms_info.dsm_addr) {
+        return 0;
+    }
+
+    addr = reserved_range_push(2 * PAGE_SIZE);
+    if (!addr) {
+        return -1;
+    }
+
+    nvdimms_info.dsm_addr = addr;
+    nvdimms_info.dsm_size = PAGE_SIZE * 2;
+
+    dsm_ram_mr = g_new(MemoryRegion, 1);
+    memory_region_init_ram(dsm_ram_mr, NULL, "dsm_ram", PAGE_SIZE,
+                           &error_abort);
+    vmstate_register_ram_global(dsm_ram_mr);
+    memory_region_add_subregion(get_system_memory(), addr, dsm_ram_mr);
+
+    dsm_mmio_mr = g_new(MemoryRegion, 1);
+    memory_region_init_io(dsm_mmio_mr, NULL, &dsm_ops, dsm_ram_mr,
+                          "dsm_mmio", PAGE_SIZE);
+    memory_region_add_subregion(get_system_memory(), addr + PAGE_SIZE,
+                                dsm_mmio_mr);
+    return 0;
+}
+
 void pc_nvdimm_build_nfit_table(GArray *table_offsets, GArray *table_data,
                                 GArray *linker)
 {
-    GSList *list = get_nvdimm_built_list();
+    GSList *list;
     size_t total;
     char *buf;
     int nfit_start, nr;
 
+    if (build_dsm_buffer()) {
+        fprintf(stderr, "do not have enough space for DSM buffer.\n");
+        return;
+    }
+
+    list = get_nvdimm_built_list();
     nr = get_nvdimm_device_number(list);
     total = get_nfit_total_size(nr);
 
-- 
2.1.0