On Fri, 1 Jun 2018 16:10:25 +0800 junyan...@gmx.com wrote: > From: Junyan He <junyan...@intel.com> > > When QEMU emulates vNVDIMM labels and migrates vNVDIMM devices, it > needs to know whether the backend storage is a real persistent memory, > in order to decide whether special operations should be performed to > ensure the data persistence. > > This boolean option 'pmem' allows users to specify whether the backend > storage of memory-backend-file is a real persistent memory. If > 'pmem=on', QEMU will set the flag RAM_PMEM in the RAM block of the > corresponding memory region. > > Signed-off-by: Junyan He <junyan...@intel.com> > Signed-off-by: Haozhong Zhang <haozhong.zh...@intel.com> > --- > backends/hostmem-file.c | 27 ++++++++++++++++++++++++++- > docs/nvdimm.txt | 14 ++++++++++++++ > exec.c | 9 +++++++++ > include/exec/memory.h | 6 ++++++ > include/exec/ram_addr.h | 3 +++ > qemu-options.hx | 7 +++++++ > 6 files changed, 65 insertions(+), 1 deletion(-) > > diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c > index 34c68bb..ccca7a1 100644 > --- a/backends/hostmem-file.c > +++ b/backends/hostmem-file.c > @@ -34,6 +34,7 @@ struct HostMemoryBackendFile { > bool discard_data; > char *mem_path; > uint64_t align; > + bool is_pmem; > }; > > static void > @@ -59,7 +60,8 @@ 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 +133,26 @@ 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(OBJECT(backend))); why not to use 'o' vs backend like on previous line or other way around?
> + return; > + } > + > + fb->is_pmem = value; > +} > + > static void file_backend_unparent(Object *obj) > { > HostMemoryBackend *backend = MEMORY_BACKEND(obj); > @@ -162,6 +184,9 @@ 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 e903d8b..bcb2032 100644 > --- a/docs/nvdimm.txt > +++ b/docs/nvdimm.txt > @@ -153,3 +153,17 @@ guest NVDIMM region mapping structure. This unarmed > flag indicates > guest software that this vNVDIMM device contains a region that cannot > accept persistent writes. In result, for example, the guest Linux > NVDIMM driver, marks such vNVDIMM device as read-only. > + > +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=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). > + > +References > +---------- > + > +[1] SNIA NVM Programming Model: > https://www.snia.org/sites/default/files/technical_work/final/NVMProgrammingModel_v1.2.pdf > +[2] PMDK: http://pmem.io/pmdk/ > diff --git a/exec.c b/exec.c > index f2082fa..f066705 100644 > --- a/exec.c > +++ b/exec.c > @@ -2061,6 +2061,9 @@ 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; > @@ -3971,6 +3974,11 @@ err: > return ret; > } > > +bool ramblock_is_pmem(RAMBlock *rb) > +{ > + return rb->flags & RAM_PMEM; > +} > + > #endif > > void page_size_init(void) > @@ -4069,3 +4077,4 @@ void mtree_print_dispatch(fprintf_function mon, void *f, > } > > #endif > + > diff --git a/include/exec/memory.h b/include/exec/memory.h > index 3b68a43..6523512 100644 > --- a/include/exec/memory.h > +++ b/include/exec/memory.h > @@ -119,6 +119,11 @@ typedef struct IOMMUNotifier IOMMUNotifier; > */ > #define RAM_UF_ZEROPAGE (1 << 3) > > +/* QEMU_RAM_PMEM is available on this RAMBlock to specify that the > + * memory is a persistent kind memory. > + */ > +#define RAM_PMEM (1 << 4) > + > static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn, > IOMMUNotifierFlag flags, > hwaddr start, hwaddr end) > @@ -611,6 +616,7 @@ void memory_region_init_resizeable_ram(MemoryRegion *mr, > * @ram_flags: specify properties of this memory region, which can be one or > * bit-or of following values: > * - RAM_SHARED: memory must be mmaped with the MAP_SHARED flag > + * - RAM_PMEM: the backend @path is persistent memory not sure that we need to mention backend in general API, maybe would be better: - RAM_PMEM: memory is persistent memory and in other places the same > * Other bits are ignored. > * @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 b478455..722bd1a 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); > unsigned long last_ram_page(void); > > @@ -84,6 +86,7 @@ unsigned long last_ram_page(void); > * @ram_flags: specify the properties of the ram block, which can be one > * or bit-or of following values > * - RAM_SHARED: mmap the back 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 back 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 2f61ea4..228e154 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -4042,6 +4042,13 @@ 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 backend store specified s/backend store/backing file/ > +by @option{mem-path} is on the persistent memory that can be accessed > +in the SNIA NVM programming model (e.g. Intel NVDIMM). s/in/using/ > +If @address@hidden, QEMU will take necessary operations to ^^^^^^^^^^^^^^^ I don't get it, could you clarify? > +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.