@@ -12,6 +12,7 @@
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu-common.h"
+#include "qemu/error-report.h"
#include "sysemu/hostmem.h"
#include "sysemu/sysemu.h"
#include "qom/object_interfaces.h"
@@ -34,6 +35,7 @@ struct HostMemoryBackendFile {
bool discard_data;
char *mem_path;
uint64_t align;
+ bool is_pmem;
};
static void
@@ -59,7 +61,8 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
path,
backend->size, fb->align,
- backend->share ? RAM_SHARED : 0,
+ (backend->share ? RAM_SHARED : 0) |
+ (fb->is_pmem ? RAM_PMEM : 0),
fb->mem_path, errp);
g_free(path);
}
@@ -131,6 +134,39 @@ static void file_memory_backend_set_align(Object *o, Visitor *v,
error_propagate(errp, local_err);
}
+static bool file_memory_backend_get_pmem(Object *o, Error **errp)
+{
+ return MEMORY_BACKEND_FILE(o)->is_pmem;
+}
+
+static void file_memory_backend_set_pmem(Object *o, bool value, Error **errp)
+{
+ HostMemoryBackend *backend = MEMORY_BACKEND(o);
+ HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
+
+ if (host_memory_backend_mr_inited(backend)) {
+ error_setg(errp, "cannot change property 'pmem' of %s '%s'",
+ object_get_typename(o),
+ object_get_canonical_path_component(o));
+ return;
+ }
+
+#ifndef CONFIG_LIBPMEM
+ if (value) {
+ Error *local_err = NULL;
+ error_setg(&local_err,
+ "Lack of libpmem support while setting the 'pmem=on'"
+ " of %s '%s'. We can't ensure data persistence.",
+ object_get_typename(o),
+ object_get_canonical_path_component(o));
+ error_propagate(errp, local_err);
+ return;
+ }
+#endif
+
+ fb->is_pmem = value;
+}
+
static void file_backend_unparent(Object *obj)
{
HostMemoryBackend *backend = MEMORY_BACKEND(obj);
@@ -162,6 +198,9 @@ file_backend_class_init(ObjectClass *oc, void *data)
file_memory_backend_get_align,
file_memory_backend_set_align,
NULL, NULL, &error_abort);
+ object_class_property_add_bool(oc, "pmem",
+ file_memory_backend_get_pmem, file_memory_backend_set_pmem,
+ &error_abort);
}
static void file_backend_instance_finalize(Object *o)
@@ -173,3 +173,25 @@ There are currently two valid values for this option:
the NVDIMMs in the event of power loss. This implies that the
platform also supports flushing dirty data through the memory
controller on power loss.
+
+If the vNVDIMM backend is on the host persistent memory that can be
+accessed in SNIA NVM Programming Model [1] (e.g., Intel NVDIMM), it's
+suggested to set the 'pmem' option of memory-backend-file to 'on'. When
+'pmem' is 'on' and QEMU is built with libpmem [2] support (configured with
+--enable-libpmem), QEMU will take necessary operations to guarantee the
+persistence of its own writes to the vNVDIMM backend(e.g., in vNVDIMM label
+emulation and live migration). If 'pmem' is 'on' while there is no libpmem
+support, qemu will exit and report a "lack of libpmem support" message to
+ensure the persistence is available. For example, if we want to ensure the
+persistence for some backend file, use the QEMU command line:
+
+ -object memory-backend-file,id=nv_mem,mem-path=/XXX/yyy,size=4G,pmem=on
+
+References
+----------
+
+[1] NVM Programming Model (NPM)
+ Version 1.2
+ https://www.snia.org/sites/default/files/technical_work/final/NVMProgrammingModel_v1.2.pdf
+[2] Persistent Memory Development Kit (PMDK), formerly known as NVML project, home page:
+ http://pmem.io/pmdk/
@@ -2245,6 +2245,9 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
Error *local_err = NULL;
int64_t file_size;
+ /* Just support these ram flags by now. */
+ assert(ram_flags == 0 || (ram_flags & (RAM_SHARED | RAM_PMEM)));
+
if (xen_enabled()) {
error_setg(errp, "-mem-path not supported with Xen");
return NULL;
@@ -4072,6 +4075,11 @@ err:
return ret;
}
+bool ramblock_is_pmem(RAMBlock *rb)
+{
+ return rb->flags & RAM_PMEM;
+}
+
#endif
void page_size_init(void)
@@ -123,6 +123,9 @@ typedef struct IOMMUNotifier IOMMUNotifier;
/* RAM can be migrated */
#define RAM_MIGRATABLE (1 << 4)
+/* RAM is a persistent kind memory */
+#define RAM_PMEM (1 << 5)
+
static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
IOMMUNotifierFlag flags,
hwaddr start, hwaddr end,
@@ -654,6 +657,7 @@ void memory_region_init_resizeable_ram(MemoryRegion *mr,
* (getpagesize()) will be used.
* @ram_flags: Memory region features:
* - RAM_SHARED: memory must be mmaped with the MAP_SHARED flag
+ * - RAM_PMEM: the memory is persistent memory
* Other bits are ignored now.
* @path: the path in which to allocate the RAM.
* @errp: pointer to Error*, to store an error if it happens.
@@ -70,6 +70,8 @@ static inline unsigned long int ramblock_recv_bitmap_offset(void *host_addr,
return host_addr_offset >> TARGET_PAGE_BITS;
}
+bool ramblock_is_pmem(RAMBlock *rb);
+
long qemu_getrampagesize(void);
/**
@@ -83,6 +85,7 @@ long qemu_getrampagesize(void);
* @ram_flags: specify the properties of the ram block, which can be one
* or bit-or of following values
* - RAM_SHARED: mmap the backing file or device with MAP_SHARED
+ * - RAM_PMEM: the backend @mem_path or @fd is persistent memory
* Other bits are ignored.
* @mem_path or @fd: specify the backing file or device
* @errp: pointer to Error*, to store an error if it happens
@@ -4070,6 +4070,13 @@ requires an alignment different than the default one used by QEMU, eg
the device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
such cases, users can specify the required alignment via this option.
+The @option{pmem} option specifies whether the backing file specified
+by @option{mem-path} is on the persistent memory that can be accessed
+using the SNIA NVM programming model (e.g. Intel NVDIMM).
+If @option{pmem} is set to 'on', QEMU will take necessary operations to
+guarantee the persistence of its own writes to @option{mem-path}
+(e.g. in vNVDIMM label emulation and live migration).
+
@item -object memory-backend-ram,id=@var{id},merge=@var{on|off},dump=@var{on|off},share=@var{on|off},prealloc=@var{on|off},size=@var{size},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave}
Creates a memory backend object, which can be used to back the guest RAM.