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postcopy: helper for waking shared 

Provide a helper to send a 'wake' request on a userfaultfd for
a shared process.
The address in the clients address space is specified together
with the RAMBlock it was resolved to.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@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 17:21:14 +00:00 committed by Michael S. Tsirkin
parent 375318d03f
commit 5efc356403
3 changed files with 37 additions and 0 deletions
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26
migration/postcopy-ram.c
View File

@ -525,6 +525,25 @@ static int ram_block_enable_notify(const char *block_name, void *host_addr,
return 0;
}
int postcopy_wake_shared(struct PostCopyFD *pcfd,
uint64_t client_addr,
RAMBlock *rb)
{
size_t pagesize = qemu_ram_pagesize(rb);
struct uffdio_range range;
int ret;
trace_postcopy_wake_shared(client_addr, qemu_ram_get_idstr(rb));
range.start = client_addr & ~(pagesize - 1);
range.len = pagesize;
ret = ioctl(pcfd->fd, UFFDIO_WAKE, &range);
if (ret) {
error_report("%s: Failed to wake: %zx in %s (%s)",
__func__, (size_t)client_addr, qemu_ram_get_idstr(rb),
strerror(errno));
}
return ret;
}
/*
* Callback from shared fault handlers to ask for a page,
* the page must be specified by a RAMBlock and an offset in that rb
@ -961,6 +980,13 @@ void *postcopy_get_tmp_page(MigrationIncomingState *mis)
return NULL;
}
int postcopy_wake_shared(struct PostCopyFD *pcfd,
uint64_t client_addr,
RAMBlock *rb)
{
assert(0);
return -1;
}
#endif
/* ------------------------------------------------------------------------- */

10
migration/postcopy-ram.h
View File

@ -164,6 +164,16 @@ struct PostCopyFD {
*/
void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
/* postcopy_wake_shared: Notify a client ufd that a page is available
*
* Returns 0 on success
*
* @pcfd: Structure with fd, handler and name as above
* @client_addr: Address in the client program, not QEMU
* @rb: The RAMBlock the page is in
*/
int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr,
RAMBlock *rb);
/* Callback from shared fault handlers to ask for a page */
int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
uint64_t client_addr, uint64_t offset);

1
migration/trace-events
View File

@ -199,6 +199,7 @@ postcopy_ram_incoming_cleanup_entry(void) ""
postcopy_ram_incoming_cleanup_exit(void) ""
postcopy_ram_incoming_cleanup_join(void) ""
postcopy_request_shared_page(const char *sharer, const char *rb, uint64_t rb_offset) "for %s in %s offset 0x%"PRIx64
postcopy_wake_shared(uint64_t client_addr, const char *rb) "at 0x%"PRIx64" in %s"
save_xbzrle_page_skipping(void) ""
save_xbzrle_page_overflow(void) ""