File libxc-sr-restore-handle_incoming_page_data.patch of Package xen.21116
From: Olaf Hering <olaf@aepfle.de>
Date: Thu, 29 Oct 2020 16:13:10 +0100
Subject: libxc sr restore handle_incoming_page_data
tools/guest: restore: write data directly into guest
Read incoming migration stream directly into the guest memory.
This avoids the memory allocation and copying, and the resulting
performance penalty.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
tools/libxc/xc_sr_common.h | 1 +
tools/libxc/xc_sr_restore.c | 132 ++++++++++++++++++++++++++++++++++--
2 files changed, 129 insertions(+), 4 deletions(-)
--- xen-4.14.0-testing.orig/tools/libxc/xc_sr_common.h
+++ xen-4.14.0-testing/tools/libxc/xc_sr_common.h
@@ -232,6 +232,7 @@ struct xc_sr_restore_arrays {
xen_pfn_t mfns[MAX_BATCH_SIZE];
int map_errs[MAX_BATCH_SIZE];
void *guest_data[MAX_BATCH_SIZE];
+ struct iovec iov[MAX_BATCH_SIZE];
/* populate_pfns */
xen_pfn_t pp_mfns[MAX_BATCH_SIZE];
--- xen-4.14.0-testing.orig/tools/libxc/xc_sr_restore.c
+++ xen-4.14.0-testing/tools/libxc/xc_sr_restore.c
@@ -393,6 +393,122 @@ err:
}
/*
+ * Handle PAGE_DATA record from the stream.
+ * Given a list of pfns, their types, and a block of page data from the
+ * stream, populate and record their types, map the relevant subset and copy
+ * the data into the guest.
+ */
+static int handle_incoming_page_data(struct xc_sr_context *ctx,
+ struct xc_sr_rhdr *rhdr)
+{
+ xc_interface *xch = ctx->xch;
+ struct xc_sr_restore_arrays *m = ctx->restore.m;
+ struct xc_sr_rec_page_data_header *pages = &m->pages;
+ uint64_t *pfn_nums = m->pages.pfn;
+ uint32_t i;
+ int rc, iov_idx;
+
+ rc = handle_static_data_end_v2(ctx);
+ if ( rc )
+ goto err;
+
+ /* First read and verify the header */
+ rc = read_exact(ctx->fd, pages, sizeof(*pages));
+ if ( rc )
+ {
+ PERROR("Could not read rec_pfn header");
+ goto err;
+ }
+
+ if ( verify_rec_page_hdr(ctx, rhdr->length, pages) == false )
+ {
+ rc = -1;
+ goto err;
+ }
+
+ /* Then read and verify the incoming pfn numbers */
+ rc = read_exact(ctx->fd, pfn_nums, sizeof(*pfn_nums) * pages->count);
+ if ( rc )
+ {
+ PERROR("Could not read rec_pfn data");
+ goto err;
+ }
+
+ if ( verify_rec_page_pfns(ctx, rhdr->length, pages) == false )
+ {
+ rc = -1;
+ goto err;
+ }
+
+ /* Finally read and verify the incoming pfn data */
+ rc = map_guest_pages(ctx, pages);
+ if ( rc )
+ goto err;
+
+ /* Prepare read buffers, either guest or throw away memory */
+ for ( i = 0, iov_idx = 0; i < pages->count; i++ )
+ {
+ if ( !m->guest_data[i] )
+ continue;
+
+ m->iov[iov_idx].iov_len = PAGE_SIZE;
+ if ( ctx->restore.verify )
+ m->iov[iov_idx].iov_base = ctx->restore.verify_buf + i * PAGE_SIZE;
+ else
+ m->iov[iov_idx].iov_base = m->guest_data[i];
+ iov_idx++;
+ }
+
+ if ( !iov_idx )
+ goto done;
+
+ rc = readv_exact(ctx->fd, m->iov, iov_idx);
+ if ( rc )
+ {
+ PERROR("read of %d pages failed", iov_idx);
+ goto err;
+ }
+
+ /* Post-processing of pfn data */
+ for ( i = 0, iov_idx = 0; i < pages->count; i++ )
+ {
+ if ( !m->guest_data[i] )
+ continue;
+
+ rc = ctx->restore.ops.localise_page(ctx, m->types[i], m->iov[iov_idx].iov_base);
+ if ( rc )
+ {
+ ERROR("Failed to localise pfn %#"PRIpfn" (type %#"PRIx32")",
+ m->pfns[i], m->types[i] >> XEN_DOMCTL_PFINFO_LTAB_SHIFT);
+ goto err;
+
+ }
+
+ if ( ctx->restore.verify )
+ {
+ if ( memcmp(m->guest_data[i], m->iov[iov_idx].iov_base, PAGE_SIZE) )
+ {
+ ERROR("verify pfn %#"PRIpfn" failed (type %#"PRIx32")",
+ m->pfns[i], m->types[i] >> XEN_DOMCTL_PFINFO_LTAB_SHIFT);
+ }
+ }
+
+ iov_idx++;
+ }
+
+done:
+ rc = 0;
+
+err:
+ if ( ctx->restore.guest_mapping )
+ {
+ xenforeignmemory_unmap(xch->fmem, ctx->restore.guest_mapping, ctx->restore.nr_mapped_pages);
+ ctx->restore.guest_mapping = NULL;
+ }
+ return rc;
+}
+
+/*
* Handle PAGE_DATA record from an existing buffer
* Given a list of pfns, their types, and a block of page data from the
* stream, populate and record their types, map the relevant subset and copy
@@ -773,11 +889,19 @@ static int process_incoming_record_heade
struct xc_sr_record rec;
int rc;
- rc = read_record_data(ctx, ctx->fd, rhdr, &rec);
- if ( rc )
- return rc;
+ switch ( rhdr->type )
+ {
+ case REC_TYPE_PAGE_DATA:
+ rc = handle_incoming_page_data(ctx, rhdr);
+ break;
+ default:
+ rc = read_record_data(ctx, ctx->fd, rhdr, &rec);
+ if ( rc == 0 )
+ rc = process_buffered_record(ctx, &rec);;
+ break;
+ }
- return process_buffered_record(ctx, &rec);
+ return rc;
}