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-rw-r--r--backends/hostmem-file.c43
-rw-r--r--docs/nvdimm.txt22
-rw-r--r--exec.c8
-rw-r--r--include/exec/memory.h4
-rw-r--r--include/exec/ram_addr.h3
-rw-r--r--qemu-options.hx7
6 files changed, 85 insertions, 2 deletions
diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
index 34c68bb..2476dcb 100644
--- a/backends/hostmem-file.c
+++ b/backends/hostmem-file.c
@@ -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"
@@ -31,9 +32,10 @@ typedef struct HostMemoryBackendFile HostMemoryBackendFile;
struct HostMemoryBackendFile {
HostMemoryBackend parent_obj;
- bool discard_data;
char *mem_path;
uint64_t align;
+ bool discard_data;
+ 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)
diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt
index 24b443b..5f158a6 100644
--- a/docs/nvdimm.txt
+++ b/docs/nvdimm.txt
@@ -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 in 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/
diff --git a/exec.c b/exec.c
index 3b8f914..fa3fbc6 100644
--- a/exec.c
+++ b/exec.c
@@ -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 & ~(RAM_SHARED | RAM_PMEM)) == 0);
+
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)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 30e7166..cd62029 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -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.
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 8a4a9bc..3abb639 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -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
diff --git a/qemu-options.hx b/qemu-options.hx
index b1bf0f4..9b920f2 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -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 in host 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.