nvdimm acpi: emulate dsm method

Emulate dsm method after IO VM-exit

Currently, we only introduce the framework and no function is actually
supported
Signed-off-by: NXiao Guangrong <guangrong.xiao@linux.intel.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/acpi/nvdimm.c

@@ -390,15 +390,71 @@ struct NvdimmDsmOut {
 } QEMU_PACKED;
 typedef struct NvdimmDsmOut NvdimmDsmOut;
 
+struct NvdimmDsmFunc0Out {
+    /* the size of buffer filled by QEMU. */
+     uint32_t len;
+     uint32_t supported_func;
+} QEMU_PACKED;
+typedef struct NvdimmDsmFunc0Out NvdimmDsmFunc0Out;
+
+struct NvdimmDsmFuncNoPayloadOut {
+    /* the size of buffer filled by QEMU. */
+     uint32_t len;
+     uint32_t func_ret_status;
+} QEMU_PACKED;
+typedef struct NvdimmDsmFuncNoPayloadOut NvdimmDsmFuncNoPayloadOut;
+
 static uint64_t
 nvdimm_dsm_read(void *opaque, hwaddr addr, unsigned size)
 {
+    nvdimm_debug("BUG: we never read _DSM IO Port.\n");
     return 0;
 }
 
 static void
 nvdimm_dsm_write(void *opaque, hwaddr addr, uint64_t val, unsigned size)
 {
+    NvdimmDsmIn *in;
+    hwaddr dsm_mem_addr = val;
+
+    nvdimm_debug("dsm memory address %#" HWADDR_PRIx ".\n", dsm_mem_addr);
+
+    /*
+     * The DSM memory is mapped to guest address space so an evil guest
+     * can change its content while we are doing DSM emulation. Avoid
+     * this by copying DSM memory to QEMU local memory.
+     */
+    in = g_malloc(TARGET_PAGE_SIZE);
+    cpu_physical_memory_read(dsm_mem_addr, in, TARGET_PAGE_SIZE);
+
+    le32_to_cpus(&in->revision);
+    le32_to_cpus(&in->function);
+    le32_to_cpus(&in->handle);
+
+    nvdimm_debug("Revision %#x Handler %#x Function %#x.\n", in->revision,
+                 in->handle, in->function);
+
+    /*
+     * function 0 is called to inquire which functions are supported by
+     * OSPM
+     */
+    if (in->function == 0) {
+        NvdimmDsmFunc0Out func0 = {
+            .len = cpu_to_le32(sizeof(func0)),
+             /* No function supported other than function 0 */
+            .supported_func = cpu_to_le32(0),
+        };
+        cpu_physical_memory_write(dsm_mem_addr, &func0, sizeof func0);
+    } else {
+        /* No function except function 0 is supported yet. */
+        NvdimmDsmFuncNoPayloadOut out = {
+            .len = cpu_to_le32(sizeof(out)),
+            .func_ret_status = cpu_to_le32(1)  /* Not Supported */,
+        };
+        cpu_physical_memory_write(dsm_mem_addr, &out, sizeof(out));
+    }
+
+    g_free(in);
 }
 
 static const MemoryRegionOps nvdimm_dsm_ops = {

include/hw/mem/nvdimm.h

@@ -25,6 +25,14 @@
 
 #include "hw/mem/pc-dimm.h"
 
+#define NVDIMM_DEBUG 0
+#define nvdimm_debug(fmt, ...)                                \
+    do {                                                      \
+        if (NVDIMM_DEBUG) {                                   \
+            fprintf(stderr, "nvdimm: " fmt, ## __VA_ARGS__);  \
+        }                                                     \
+    } while (0)
+
 #define TYPE_NVDIMM             "nvdimm"
 
 #define NVDIMM_DSM_MEM_FILE     "etc/acpi/nvdimm-mem"