| Message ID | 20180117081325.11924-2-haozhong.zhang@intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,1/3] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap() | expand |
> index 50385e3f81..dd5876471f 100644 > --- a/include/qemu/mmap-alloc.h > +++ b/include/qemu/mmap-alloc.h > @@ -7,7 +7,8 @@ size_t qemu_fd_getpagesize(int fd); > > size_t qemu_mempath_getpagesize(const char *mem_path); > > -void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared); > +void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared, > + OnOffAuto sync); > > void qemu_ram_munmap(void *ptr, size_t size); > And Marcel plans to add a remappable flag ... Is it time we switched to a flags field? > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > index adb3758275..0ff10cb529 100644 > --- a/include/qemu/osdep.h > +++ b/include/qemu/osdep.h > @@ -372,6 +372,24 @@ void qemu_anon_ram_free(void *ptr, size_t size); > # define QEMU_VMALLOC_ALIGN getpagesize() > #endif > > +/* > + * MAP_SHARED_VALIDATE and MAP_SYNC were introduced in Linux kernel > + * 4.15, so they may not be defined when compiling on older kernels. > + */ > +#ifdef CONFIG_LINUX > +#ifndef MAP_SHARED_VALIDATE > +#define MAP_SHARED_VALIDATE 0x3 > +#endif > +#ifndef MAP_SYNC > +#define MAP_SYNC 0x80000 > +#endif > +#define QEMU_HAS_MAP_SYNC true > +#else /* !CONFIG_LINUX */ > +#define MAP_SHARED_VALIDATE 0x0 > +#define MAP_SYNC 0x0 > +#define QEMU_HAS_MAP_SYNC false > +#endif /* CONFIG_LINUX */ > + > #ifdef CONFIG_POSIX > struct qemu_signalfd_siginfo { > uint32_t ssi_signo; /* Signal number */ Please just import this into standard-headers from Linux.
On 01/24/18 22:20 +0200, Michael S. Tsirkin wrote: > > index 50385e3f81..dd5876471f 100644 > > --- a/include/qemu/mmap-alloc.h > > +++ b/include/qemu/mmap-alloc.h > > @@ -7,7 +7,8 @@ size_t qemu_fd_getpagesize(int fd); > > > > size_t qemu_mempath_getpagesize(const char *mem_path); > > > > -void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared); > > +void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared, > > + OnOffAuto sync); > > > > void qemu_ram_munmap(void *ptr, size_t size); > > > > And Marcel plans to add a remappable flag ... Is it time we > switched to a flags field? Yes. Some patches on my hands are going to add another field to this function, so let's switch to flags. > > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > > index adb3758275..0ff10cb529 100644 > > --- a/include/qemu/osdep.h > > +++ b/include/qemu/osdep.h > > @@ -372,6 +372,24 @@ void qemu_anon_ram_free(void *ptr, size_t size); > > # define QEMU_VMALLOC_ALIGN getpagesize() > > #endif > > > > +/* > > + * MAP_SHARED_VALIDATE and MAP_SYNC were introduced in Linux kernel > > + * 4.15, so they may not be defined when compiling on older kernels. > > + */ > > +#ifdef CONFIG_LINUX > > +#ifndef MAP_SHARED_VALIDATE > > +#define MAP_SHARED_VALIDATE 0x3 > > +#endif > > +#ifndef MAP_SYNC > > +#define MAP_SYNC 0x80000 > > +#endif > > +#define QEMU_HAS_MAP_SYNC true > > +#else /* !CONFIG_LINUX */ > > +#define MAP_SHARED_VALIDATE 0x0 > > +#define MAP_SYNC 0x0 > > +#define QEMU_HAS_MAP_SYNC false > > +#endif /* CONFIG_LINUX */ > > + > > #ifdef CONFIG_POSIX > > struct qemu_signalfd_siginfo { > > uint32_t ssi_signo; /* Signal number */ > > Please just import this into standard-headers from Linux. > Sure, I'll move it to a new file include/standard-headers/linux/mman.h. Thanks, Haozhong
diff --git a/exec.c b/exec.c index 8fba88ae1c..f4254cb6d3 100644 --- a/exec.c +++ b/exec.c @@ -1646,7 +1646,7 @@ static void *file_ram_alloc(RAMBlock *block, } area = qemu_ram_mmap(fd, memory, block->mr->align, - block->flags & RAM_SHARED); + block->flags & RAM_SHARED, ON_OFF_AUTO_OFF); if (area == MAP_FAILED) { error_setg_errno(errp, errno, "unable to map backing store for guest RAM"); diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h index 50385e3f81..dd5876471f 100644 --- a/include/qemu/mmap-alloc.h +++ b/include/qemu/mmap-alloc.h @@ -7,7 +7,8 @@ size_t qemu_fd_getpagesize(int fd); size_t qemu_mempath_getpagesize(const char *mem_path); -void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared); +void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared, + OnOffAuto sync); void qemu_ram_munmap(void *ptr, size_t size); diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index adb3758275..0ff10cb529 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -372,6 +372,24 @@ void qemu_anon_ram_free(void *ptr, size_t size); # define QEMU_VMALLOC_ALIGN getpagesize() #endif +/* + * MAP_SHARED_VALIDATE and MAP_SYNC were introduced in Linux kernel + * 4.15, so they may not be defined when compiling on older kernels. + */ +#ifdef CONFIG_LINUX +#ifndef MAP_SHARED_VALIDATE +#define MAP_SHARED_VALIDATE 0x3 +#endif +#ifndef MAP_SYNC +#define MAP_SYNC 0x80000 +#endif +#define QEMU_HAS_MAP_SYNC true +#else /* !CONFIG_LINUX */ +#define MAP_SHARED_VALIDATE 0x0 +#define MAP_SYNC 0x0 +#define QEMU_HAS_MAP_SYNC false +#endif /* CONFIG_LINUX */ + #ifdef CONFIG_POSIX struct qemu_signalfd_siginfo { uint32_t ssi_signo; /* Signal number */ diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 2fd8cbcc6f..b42d9719f3 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -73,7 +73,8 @@ size_t qemu_mempath_getpagesize(const char *mem_path) return getpagesize(); } -void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) +void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared, + OnOffAuto sync) { /* * Note: this always allocates at least one extra page of virtual address @@ -97,6 +98,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) #endif size_t offset; void *ptr1; + int xflags = 0; if (ptr == MAP_FAILED) { return MAP_FAILED; @@ -106,13 +108,31 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) /* Always align to host page size */ assert(align >= getpagesize()); + if (!QEMU_HAS_MAP_SYNC || !shared) { + if (sync == ON_OFF_AUTO_ON) { + return MAP_FAILED; + } + sync = ON_OFF_AUTO_OFF; + } + if (sync != ON_OFF_AUTO_OFF) { + /* MAP_SYNC is only available with MAP_SHARED_VALIDATE. */ + xflags |= MAP_SYNC | MAP_SHARED_VALIDATE; + } + offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr; + retry_mmap_fd: ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE, MAP_FIXED | (fd == -1 ? MAP_ANONYMOUS : 0) | - (shared ? MAP_SHARED : MAP_PRIVATE), + (shared ? MAP_SHARED : MAP_PRIVATE) | xflags, fd, 0); if (ptr1 == MAP_FAILED) { + if (sync == ON_OFF_AUTO_AUTO) { + xflags &= ~(MAP_SYNC | MAP_SHARED_VALIDATE); + sync = ON_OFF_AUTO_OFF; + goto retry_mmap_fd; + } + munmap(ptr, total); return MAP_FAILED; } diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 77369c92ce..ecb1c275d2 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -130,7 +130,7 @@ void *qemu_memalign(size_t alignment, size_t size) void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment) { size_t align = QEMU_VMALLOC_ALIGN; - void *ptr = qemu_ram_mmap(-1, size, align, false); + void *ptr = qemu_ram_mmap(-1, size, align, false, ON_OFF_AUTO_OFF); if (ptr == MAP_FAILED) { return NULL;
When a file supporting DAX is used as vNVDIMM backend, mmap it with MAP_SYNC flag in addition can guarantee the persistence of guest write to the backend file without other QEMU actions (e.g., periodic fsync() by QEMU). A OnOffAuto parameter 'sync' is added to qemu_ram_mmap(): - If sync == ON_OFF_AUTO_ON, qemu_ram_mmap() will try to pass MAP_SYNC to mmap(). It will then fail if the host OS or the backend file do not support MAP_SYNC, or MAP_SYNC is conflict with other flags. - If sync == ON_OFF_AUTO_OFF, qemu_ram_mmap() will never pass MAP_SYNC to mmap(). - If sync == ON_OFF_AUTO_AUTO, and * if the host OS and the backend file support MAP_SYNC, and MAP_SYNC is not conflict with other flags, qemu_ram_mmap() will work as if sync == ON_OFF_AUTO_ON. * otherwise, qemu_ram_mmap() will work as if sync == ON_OFF_AUTO_OFF. Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> --- exec.c | 2 +- include/qemu/mmap-alloc.h | 3 ++- include/qemu/osdep.h | 18 ++++++++++++++++++ util/mmap-alloc.c | 24 ++++++++++++++++++++++-- util/oslib-posix.c | 2 +- 5 files changed, 44 insertions(+), 5 deletions(-)