On 4/7/2020 4:08 PM, Paolo Bonzini wrote:
On 07/04/20 09:29, Liu, Jingqi wrote:
Ping.
Any comments are appreciated.
Hi Paolo, Richard,
Any comments about this ?
I was hoping to get a review from someone else because I have no way to
test it. But I've now queued the patch, thanks.
Hi Paolo,
Thanks for your comments.
Hi Dan,
Can you help review this patch ?
Thanks,
Jingqi
Paolo
Thanks,
Jingqi
On 4/1/2020 11:13 AM, Liu, Jingqi wrote:
If the backend file is devdax pmem character device, the alignment
specified by the option 'align=NUM' in the '-object memory-backend-file'
needs to match the alignment requirement of the devdax pmem character
device.
This patch fetches the devdax pmem file 'align', so that we can compare
it with the NUM of 'align=NUM'.
The NUM needs to be larger than or equal to the devdax pmem file 'align'.
It also fixes the problem that mmap() returns failure in qemu_ram_mmap()
when the NUM of 'align=NUM' is less than the devdax pmem file 'align'.
Cc: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: Jingqi Liu <jingqi....@intel.com>
---
exec.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 45 insertions(+), 1 deletion(-)
diff --git a/exec.c b/exec.c
index de9d949902..8221abffec 100644
--- a/exec.c
+++ b/exec.c
@@ -1736,6 +1736,42 @@ static int64_t get_file_size(int fd)
return size;
}
+static int64_t get_file_align(int fd)
+{
+ int64_t align = -1;
+#if defined(__linux__)
+ struct stat st;
+
+ if (fstat(fd, &st) < 0) {
+ return -errno;
+ }
+
+ /* Special handling for devdax character devices */
+ if (S_ISCHR(st.st_mode)) {
+ g_autofree char *subsystem_path = NULL;
+ g_autofree char *subsystem = NULL;
+
+ subsystem_path =
g_strdup_printf("/sys/dev/char/%d:%d/subsystem",
+ major(st.st_rdev),
minor(st.st_rdev));
+ subsystem = g_file_read_link(subsystem_path, NULL);
+
+ if (subsystem && g_str_has_suffix(subsystem, "/dax")) {
+ g_autofree char *align_path = NULL;
+ g_autofree char *align_str = NULL;
+
+ align_path =
g_strdup_printf("/sys/dev/char/%d:%d/device/align",
+ major(st.st_rdev),
minor(st.st_rdev));
+
+ if (g_file_get_contents(align_path, &align_str, NULL,
NULL)) {
+ return g_ascii_strtoll(align_str, NULL, 0);
+ }
+ }
+ }
+#endif /* defined(__linux__) */
+
+ return align;
+}
+
static int file_ram_open(const char *path,
const char *region_name,
bool *created,
@@ -2275,7 +2311,7 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t
size, MemoryRegion *mr,
{
RAMBlock *new_block;
Error *local_err = NULL;
- int64_t file_size;
+ int64_t file_size, file_align;
/* Just support these ram flags by now. */
assert((ram_flags & ~(RAM_SHARED | RAM_PMEM)) == 0);
@@ -2311,6 +2347,14 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t
size, MemoryRegion *mr,
return NULL;
}
+ file_align = get_file_align(fd);
+ if (file_align > 0 && mr && file_align > mr->align) {
+ error_setg(errp, "backing store align 0x%" PRIx64
+ " is larger than 'align' option 0x" RAM_ADDR_FMT,
+ file_align, mr->align);
+ return NULL;
+ }
+
new_block = g_malloc0(sizeof(*new_block));
new_block->mr = mr;
new_block->used_length = size;
