Hello, David.
On 2/3/20 3:31 PM, David Hildenbrand wrote:
We want to populate memory within a reserved memory region. Let's factor
that out.
Cc: "Michael S. Tsirkin" <m...@redhat.com>
Cc: Greg Kurz <gr...@kaod.org>
Cc: Murilo Opsfelder Araujo <muri...@linux.ibm.com>
Cc: Eduardo Habkost <ehabk...@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
Signed-off-by: David Hildenbrand <da...@redhat.com>
---
Acked-by: Murilo Opsfelder Araujo <muri...@linux.ibm.com>
A minor comment below.
util/mmap-alloc.c | 89 +++++++++++++++++++++++++----------------------
1 file changed, 47 insertions(+), 42 deletions(-)
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
index 43a26f38a8..f043ccb0ab 100644
--- a/util/mmap-alloc.c
+++ b/util/mmap-alloc.c
@@ -114,6 +114,50 @@ static void *mmap_reserve(size_t size, int fd)
return mmap(0, size, PROT_NONE, flags, fd, 0);
}
+/*
+ * Populate memory in a reserved region from the given fd (if any).
+ */
+static void *mmap_populate(void *ptr, size_t size, int fd, bool shared,
+ bool is_pmem)
+{
+ int map_sync_flags = 0;
+ int flags = MAP_FIXED;
+ void *new_ptr;
Do you think another name would be welcome here, e.g.: "populated_ptr" or
"populated_memptr" or just "populated"?
+
+ flags |= fd == -1 ? MAP_ANONYMOUS : 0;
+ flags |= shared ? MAP_SHARED : MAP_PRIVATE;
+ if (shared && is_pmem) {
+ map_sync_flags = MAP_SYNC | MAP_SHARED_VALIDATE;
+ }
+
+ new_ptr = mmap(ptr, size, PROT_READ | PROT_WRITE, flags | map_sync_flags,
+ fd, 0);
+ if (new_ptr == MAP_FAILED && map_sync_flags) {
+ if (errno == ENOTSUP) {
+ char *proc_link = g_strdup_printf("/proc/self/fd/%d", fd);
+ char *file_name = g_malloc0(PATH_MAX);
+ int len = readlink(proc_link, file_name, PATH_MAX - 1);
+
+ if (len < 0) {
+ len = 0;
+ }
+ file_name[len] = '\0';
+ fprintf(stderr, "Warning: requesting persistence across crashes "
+ "for backend file %s failed. Proceeding without "
+ "persistence, data might become corrupted in case of host "
+ "crash.\n", file_name);
+ g_free(proc_link);
+ g_free(file_name);
+ }
+ /*
+ * If mmap failed with MAP_SHARED_VALIDATE | MAP_SYNC, we will try
+ * again without these flags to handle backwards compatibility.
+ */
+ new_ptr = mmap(ptr, size, PROT_READ | PROT_WRITE, flags, fd, 0);
+ }
+ return new_ptr;
+}
+
static inline size_t mmap_pagesize(int fd)
{
#if defined(__powerpc64__) && defined(__linux__)
@@ -131,12 +175,8 @@ void *qemu_ram_mmap(int fd,
bool is_pmem)
{
const size_t pagesize = mmap_pagesize(fd);
- int flags;
- int map_sync_flags = 0;
- size_t offset;
- size_t total;
- void *guardptr;
- void *ptr;
+ size_t offset, total;
+ void *ptr, *guardptr;
/*
* Note: this always allocates at least one extra page of virtual address
@@ -153,44 +193,9 @@ void *qemu_ram_mmap(int fd,
/* Always align to host page size */
assert(align >= pagesize);
- flags = MAP_FIXED;
- flags |= fd == -1 ? MAP_ANONYMOUS : 0;
- flags |= shared ? MAP_SHARED : MAP_PRIVATE;
- if (shared && is_pmem) {
- map_sync_flags = MAP_SYNC | MAP_SHARED_VALIDATE;
- }
-
offset = QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)guardptr;
- ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE,
- flags | map_sync_flags, fd, 0);
-
- if (ptr == MAP_FAILED && map_sync_flags) {
- if (errno == ENOTSUP) {
- char *proc_link, *file_name;
- int len;
- proc_link = g_strdup_printf("/proc/self/fd/%d", fd);
- file_name = g_malloc0(PATH_MAX);
- len = readlink(proc_link, file_name, PATH_MAX - 1);
- if (len < 0) {
- len = 0;
- }
- file_name[len] = '\0';
- fprintf(stderr, "Warning: requesting persistence across crashes "
- "for backend file %s failed. Proceeding without "
- "persistence, data might become corrupted in case of host "
- "crash.\n", file_name);
- g_free(proc_link);
- g_free(file_name);
- }
- /*
- * if map failed with MAP_SHARED_VALIDATE | MAP_SYNC,
- * we will remove these flags to handle compatibility.
- */
- ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE,
- flags, fd, 0);
- }
-
+ ptr = mmap_populate(guardptr + offset, size, fd, shared, is_pmem);
if (ptr == MAP_FAILED) {
munmap(guardptr, total);
return MAP_FAILED;
--
Murilo
