Extract the alignment check and sanity check out from
ram_block_discard_range() into a seperate function
ram_block_discard_range_fd(), which can be passed with an explicit fd as
input parameter.
ram_block_discard_range_fd() can be used to discard private memory range
from gmem fd with later patch. When doing private memory <-> shared
memory conversion, it requires 4KB alignment instead of
RamBlock.page_size.
Signed-off-by: Xiaoyao Li <xiaoyao...@intel.com>
---
softmmu/physmem.c | 192 ++++++++++++++++++++++++----------------------
1 file changed, 100 insertions(+), 92 deletions(-)
diff --git a/softmmu/physmem.c b/softmmu/physmem.c
index 34d580ec0d39..6ee6bc794f44 100644
--- a/softmmu/physmem.c
+++ b/softmmu/physmem.c
@@ -3425,117 +3425,125 @@ int qemu_ram_foreach_block(RAMBlockIterFunc func,
void *opaque)
return ret;
}
+static int ram_block_discard_range_fd(RAMBlock *rb, uint64_t start,
+ size_t length, int fd)
+{
+ uint8_t *host_startaddr = rb->host + start;
+ bool need_madvise, need_fallocate;
+ int ret = -1;
+
+ errno = ENOTSUP; /* If we are missing MADVISE etc */
+
+ /* The logic here is messy;
+ * madvise DONTNEED fails for hugepages
+ * fallocate works on hugepages and shmem
+ * shared anonymous memory requires madvise REMOVE
+ */
+ need_madvise = (rb->page_size == qemu_host_page_size) && (rb->fd == fd);
+ need_fallocate = fd != -1;
+
+ if (need_fallocate) {
+ /* For a file, this causes the area of the file to be zero'd
+ * if read, and for hugetlbfs also causes it to be unmapped
+ * so a userfault will trigger.
+ */
+#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
+ /*
+ * We'll discard data from the actual file, even though we only
+ * have a MAP_PRIVATE mapping, possibly messing with other
+ * MAP_PRIVATE/MAP_SHARED mappings. There is no easy way to
+ * change that behavior whithout violating the promised
+ * semantics of ram_block_discard_range().
+ *
+ * Only warn, because it works as long as nobody else uses that
+ * file.
+ */
+ if (!qemu_ram_is_shared(rb)) {
+ warn_report_once("%s: Discarding RAM"
+ " in private file mappings is possibly"
+ " dangerous, because it will modify the"
+ " underlying file and will affect other"
+ " users of the file", __func__);
+ }
+
+ ret = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+ start, length);
+ if (ret) {
+ ret = -errno;
+ error_report("%s: Failed to fallocate %s:%" PRIx64 " +%zx (%d)",
+ __func__, rb->idstr, start, length, ret);
+ return ret;
+ }
+#else
+ ret = -ENOSYS;
+ error_report("%s: fallocate not available/file "
+ "%s:%" PRIx64 " +%zx (%d)",
+ __func__, rb->idstr, start, length, ret);
+ return ret;
+#endif
+ }
+
+ if (need_madvise) {
+ /* For normal RAM this causes it to be unmapped,
+ * for shared memory it causes the local mapping to disappear
+ * and to fall back on the file contents (which we just
+ * fallocate'd away).
+ */
+#if defined(CONFIG_MADVISE)
+ if (qemu_ram_is_shared(rb) && fd < 0) {
+ ret = madvise(host_startaddr, length, QEMU_MADV_REMOVE);
+ } else {
+ ret = madvise(host_startaddr, length, QEMU_MADV_DONTNEED);
+ }
+ if (ret) {
+ ret = -errno;
+ error_report("%s: Failed to discard range %s:%" PRIx64 " +%zx
(%d)",
+ __func__, rb->idstr, start, length, ret);
+ return ret;
+ }
+#else
+ ret = -ENOSYS;
+ error_report("%s: MADVISE not available %s:%" PRIx64 " +%zx (%d)",
+ __func__, rb->idstr, start, length, ret);
+ return ret;
+#endif
+ }
+
+ trace_ram_block_discard_range(rb->idstr, host_startaddr, length,
+ need_madvise, need_fallocate, ret);
+ return ret;
+}
+
/*
* Unmap pages of memory from start to start+length such that
* they a) read as 0, b) Trigger whatever fault mechanism
* the OS provides for postcopy.
+ *
* The pages must be unmapped by the end of the function.
- * Returns: 0 on success, none-0 on failure
- *
+ * Returns: 0 on success, none-0 on failure.
*/
int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length)
{
- int ret = -1;
-
uint8_t *host_startaddr = rb->host + start;
if (!QEMU_PTR_IS_ALIGNED(host_startaddr, rb->page_size)) {
error_report("%s: Unaligned start address: %p",
__func__, host_startaddr);
- goto err;
+ return -1;
}
- if ((start + length) <= rb->max_length) {
- bool need_madvise, need_fallocate;
- if (!QEMU_IS_ALIGNED(length, rb->page_size)) {
- error_report("%s: Unaligned length: %zx", __func__, length);
- goto err;
- }
-
- errno = ENOTSUP; /* If we are missing MADVISE etc */
-
- /* The logic here is messy;
- * madvise DONTNEED fails for hugepages
- * fallocate works on hugepages and shmem
- * shared anonymous memory requires madvise REMOVE
- */
- need_madvise = (rb->page_size == qemu_host_page_size);
- need_fallocate = rb->fd != -1;
- if (need_fallocate) {
- /* For a file, this causes the area of the file to be zero'd
- * if read, and for hugetlbfs also causes it to be unmapped
- * so a userfault will trigger.
- */
-#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
- /*
- * We'll discard data from the actual file, even though we only
- * have a MAP_PRIVATE mapping, possibly messing with other
- * MAP_PRIVATE/MAP_SHARED mappings. There is no easy way to
- * change that behavior whithout violating the promised
- * semantics of ram_block_discard_range().
- *
- * Only warn, because it works as long as nobody else uses that
- * file.
- */
- if (!qemu_ram_is_shared(rb)) {
- warn_report_once("%s: Discarding RAM"
- " in private file mappings is possibly"
- " dangerous, because it will modify the"
- " underlying file and will affect other"
- " users of the file", __func__);
- }
-
- ret = fallocate(rb->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
- start, length);
- if (ret) {
- ret = -errno;
- error_report("%s: Failed to fallocate %s:%" PRIx64 " +%zx
(%d)",
- __func__, rb->idstr, start, length, ret);
- goto err;
- }
-#else
- ret = -ENOSYS;
- error_report("%s: fallocate not available/file"
- "%s:%" PRIx64 " +%zx (%d)",
- __func__, rb->idstr, start, length, ret);
- goto err;
-#endif
- }
- if (need_madvise) {
- /* For normal RAM this causes it to be unmapped,
- * for shared memory it causes the local mapping to disappear
- * and to fall back on the file contents (which we just
- * fallocate'd away).
- */
-#if defined(CONFIG_MADVISE)
- if (qemu_ram_is_shared(rb) && rb->fd < 0) {
- ret = madvise(host_startaddr, length, QEMU_MADV_REMOVE);
- } else {
- ret = madvise(host_startaddr, length, QEMU_MADV_DONTNEED);
- }
- if (ret) {
- ret = -errno;
- error_report("%s: Failed to discard range "
- "%s:%" PRIx64 " +%zx (%d)",
- __func__, rb->idstr, start, length, ret);
- goto err;
- }
-#else
- ret = -ENOSYS;
- error_report("%s: MADVISE not available %s:%" PRIx64 " +%zx (%d)",
- __func__, rb->idstr, start, length, ret);
- goto err;
-#endif
- }
- trace_ram_block_discard_range(rb->idstr, host_startaddr, length,
- need_madvise, need_fallocate, ret);
- } else {
+ if ((start + length) > rb->max_length) {
error_report("%s: Overrun block '%s' (%" PRIu64 "/%zx/"
RAM_ADDR_FMT")",
__func__, rb->idstr, start, length, rb->max_length);
+ return -1;
}
-err:
- return ret;
+ if (!QEMU_IS_ALIGNED(length, rb->page_size)) {
+ error_report("%s: Unaligned length: %zx", __func__, length);
+ return -1;
+ }
+
+ return ram_block_discard_range_fd(rb, start, length, rb->fd);
}
bool ramblock_is_pmem(RAMBlock *rb)
--
2.34.1
