Override hook_ram_load to receive the pipe file descriptor
passed by source process and page address which will be
extracted to vmsplice the page data from pipe.
Signed-off-by: Lei Li <li...@linux.vnet.ibm.com>
---
migration-local.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 59 insertions(+), 0 deletions(-)
diff --git a/migration-local.c b/migration-local.c
index 76ec306..b086f38 100644
--- a/migration-local.c
+++ b/migration-local.c
@@ -231,10 +231,69 @@ static size_t qemu_local_save_ram(QEMUFile *f, void
*opaque,
return RAM_SAVE_CONTROL_NOT_SUPP;
}
+static int qemu_local_ram_load(QEMUFile *f, void *opaque,
+ ram_addr_t addr, uint64_t flags)
+{
+ QEMUFileLocal *s = opaque;
+ struct iovec iov;
+ ssize_t ret = -EINVAL;
+
+ if (!s->pipefd_received) {
+ /*
+ * send_pipefd was called at this point, and it wrote one
+ * byte to the stream.
+ */
+ qemu_get_byte(s->file);
+ s->pipefd_received = true;
+ }
+
+ if (s->pipefd_passed) {
+ void *host;
+ /*
+ * Extract the page address from the 8-byte record and
+ * read the page data from the pipe.
+ */
+ host = qemu_get_ram_ptr(addr);
+
+ iov.iov_base = host;
+ iov.iov_len = TARGET_PAGE_SIZE;
+
+ /*
+ * The flag SPLICE_F_MOVE is introduced in kernel for the page
+ * flipping feature in QEMU, which will movie pages rather than
+ * copying, previously unused.
+ *
+ * If a move is not possible the kernel will transparently falls
+ * back to copying data.
+ *
+ * For older kernels the SPLICE_F_MOVE would be ignored and a copy
+ * would occur.
+ */
+
+ ret = vmsplice(s->pipefd[0], &iov, 1, SPLICE_F_MOVE);
+ if (ret == -1) {
+ if (errno != EAGAIN && errno != EINTR) {
+ fprintf(stderr, "vmsplice() load error: %s", strerror(errno));
+ return ret;
+ }
+ DPRINTF("vmsplice load error\n");
+ } else if (ret == 0) {
+ DPRINTF(stderr, "load_page: zero read\n");
+ }
+
+ DPRINTF("vmsplice (read): %zu\n", ret);
+ return ret;
+ }
+
+ return -EINVAL;
+}
+
+
static const QEMUFileOps pipe_read_ops = {
.get_fd = qemu_local_get_sockfd,
.get_buffer = qemu_local_get_buffer,
.close = qemu_local_close,
+ .hook_ram_load = qemu_local_ram_load
};
static const QEMUFileOps pipe_write_ops = {
--
1.7.7.6
