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vhost: Huge page align and merge

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Align RAMBlocks to page size alignment, and adjust the merging code
to deal with partial overlap due to that alignment.

This is needed for postcopy so that we can place/fetch whole hugepages
when under userfault.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Dr. David Alan Gilbert 2018-03-12 17:21:21 +00:00 committed by Michael S. Tsirkin
parent 46343570c0
commit c1ece84e7c
2 changed files with 58 additions and 11 deletions
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3
hw/virtio/trace-events
View File

@ -3,7 +3,8 @@
# hw/virtio/vhost.c
vhost_commit(bool started, bool changed) "Started: %d Changed: %d"
vhost_region_add_section(const char *name, uint64_t gpa, uint64_t size, uint64_t host) "%s: 0x%"PRIx64"+0x%"PRIx64" @ 0x%"PRIx64
vhost_region_add_section_abut(const char *name, uint64_t new_size) "%s: 0x%"PRIx64
vhost_region_add_section_merge(const char *name, uint64_t new_size, uint64_t gpa, uint64_t owr) "%s: size: 0x%"PRIx64 " gpa: 0x%"PRIx64 " owr: 0x%"PRIx64
vhost_region_add_section_aligned(const char *name, uint64_t gpa, uint64_t size, uint64_t host) "%s: 0x%"PRIx64"+0x%"PRIx64" @ 0x%"PRIx64
vhost_section(const char *name, int r) "%s:%d"
# hw/virtio/vhost-user.c

66
hw/virtio/vhost.c
View File

@ -522,10 +522,28 @@ static void vhost_region_add_section(struct vhost_dev *dev,
uint64_t mrs_gpa = section->offset_within_address_space;
uintptr_t mrs_host = (uintptr_t)memory_region_get_ram_ptr(section->mr) +
section->offset_within_region;
RAMBlock *mrs_rb = section->mr->ram_block;
size_t mrs_page = qemu_ram_pagesize(mrs_rb);
trace_vhost_region_add_section(section->mr->name, mrs_gpa, mrs_size,
mrs_host);
/* Round the section to it's page size */
/* First align the start down to a page boundary */
uint64_t alignage = mrs_host & (mrs_page - 1);
if (alignage) {
mrs_host -= alignage;
mrs_size += alignage;
mrs_gpa -= alignage;
}
/* Now align the size up to a page boundary */
alignage = mrs_size & (mrs_page - 1);
if (alignage) {
mrs_size += mrs_page - alignage;
}
trace_vhost_region_add_section_aligned(section->mr->name, mrs_gpa, mrs_size,
mrs_host);
if (dev->n_tmp_sections) {
/* Since we already have at least one section, lets see if
* this extends it; since we're scanning in order, we only
@ -542,18 +560,46 @@ static void vhost_region_add_section(struct vhost_dev *dev,
prev_sec->offset_within_region;
uint64_t prev_host_end = range_get_last(prev_host_start, prev_size);
if (prev_gpa_end + 1 == mrs_gpa &&
prev_host_end + 1 == mrs_host &&
section->mr == prev_sec->mr &&
(!dev->vhost_ops->vhost_backend_can_merge ||
dev->vhost_ops->vhost_backend_can_merge(dev,
if (mrs_gpa <= (prev_gpa_end + 1)) {
/* OK, looks like overlapping/intersecting - it's possible that
* the rounding to page sizes has made them overlap, but they should
* match up in the same RAMBlock if they do.
*/
if (mrs_gpa < prev_gpa_start) {
error_report("%s:Section rounded to %"PRIx64
" prior to previous %"PRIx64,
__func__, mrs_gpa, prev_gpa_start);
/* A way to cleanly fail here would be better */
return;
}
/* Offset from the start of the previous GPA to this GPA */
size_t offset = mrs_gpa - prev_gpa_start;
if (prev_host_start + offset == mrs_host &&
section->mr == prev_sec->mr &&
(!dev->vhost_ops->vhost_backend_can_merge ||
dev->vhost_ops->vhost_backend_can_merge(dev,
mrs_host, mrs_size,
prev_host_start, prev_size))) {
/* The two sections abut */
need_add = false;
prev_sec->size = int128_add(prev_sec->size, section->size);
trace_vhost_region_add_section_abut(section->mr->name,
mrs_size + prev_size);
uint64_t max_end = MAX(prev_host_end, mrs_host + mrs_size);
need_add = false;
prev_sec->offset_within_address_space =
MIN(prev_gpa_start, mrs_gpa);
prev_sec->offset_within_region =
MIN(prev_host_start, mrs_host) -
(uintptr_t)memory_region_get_ram_ptr(prev_sec->mr);
prev_sec->size = int128_make64(max_end - MIN(prev_host_start,
mrs_host));
trace_vhost_region_add_section_merge(section->mr->name,
int128_get64(prev_sec->size),
prev_sec->offset_within_address_space,
prev_sec->offset_within_region);
} else {
error_report("%s: Overlapping but not coherent sections "
"at %"PRIx64,
__func__, mrs_gpa);
return;
}
}
}