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xen/libxc-sr-restore-handle_incoming_page_data.patch

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From: Olaf Hering <olaf@aepfle.de>
Date: Thu, 29 Oct 2020 16:13:10 +0100
Subject: libxc sr restore handle_incoming_page_data
tools: 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/libs/guest/xg_sr_common.h | 3 +
tools/libs/guest/xg_sr_restore.c | 155 ++++++++++++++++++++++++++++++-
2 files changed, 153 insertions(+), 5 deletions(-)
--- a/tools/libs/guest/xg_sr_common.h
+++ b/tools/libs/guest/xg_sr_common.h
@@ -263,6 +263,8 @@ struct xc_sr_context
xen_pfn_t *pp_pfns;
xen_pfn_t *pp_mfns;
void **guest_data;
+ struct iovec *iov;
+ struct xc_sr_rec_page_data_header *pages;
void *guest_mapping;
uint32_t nr_mapped_pages;
@@ -311,6 +313,7 @@ struct xc_sr_context
/* Sender has invoked verify mode on the stream. */
bool verify;
+ void *verify_buf;
} restore;
};
--- a/tools/libs/guest/xg_sr_restore.c
+++ b/tools/libs/guest/xg_sr_restore.c
@@ -382,6 +382,129 @@ 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_rec_page_data_header *pages = ctx->restore.pages;
+ uint64_t *pfn_nums = &pages->pfn[0];
+ 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) )
+ {
+ 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) )
+ {
+ 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++ )
+ {
+ struct iovec *iov;
+
+ if ( !ctx->restore.guest_data[i] )
+ continue;
+
+ iov = &ctx->restore.iov[iov_idx];
+ iov->iov_len = PAGE_SIZE;
+ if ( ctx->restore.verify )
+ iov->iov_base = ctx->restore.verify_buf + (i * PAGE_SIZE);
+ else
+ iov->iov_base = ctx->restore.guest_data[i];
+ iov_idx++;
+ }
+
+ if ( !iov_idx )
+ goto done;
+
+ rc = readv_exact(ctx->fd, ctx->restore.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++ )
+ {
+ void *addr;
+
+ if ( !ctx->restore.guest_data[i] )
+ continue;
+
+ addr = ctx->restore.iov[iov_idx].iov_base;
+ rc = ctx->restore.ops.localise_page(ctx, ctx->restore.types[i], addr);
+ if ( rc )
+ {
+ ERROR("Failed to localise pfn %#"PRIpfn" (type %#"PRIx32")",
+ ctx->restore.pfns[i],
+ ctx->restore.types[i] >> XEN_DOMCTL_PFINFO_LTAB_SHIFT);
+ goto err;
+
+ }
+
+ if ( ctx->restore.verify )
+ {
+ if ( memcmp(ctx->restore.guest_data[i], addr, PAGE_SIZE) )
+ {
+ ERROR("verify pfn %#"PRIpfn" failed (type %#"PRIx32")",
+ ctx->restore.pfns[i],
+ ctx->restore.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
@@ -713,6 +836,15 @@ static int process_buffered_record(struc
case REC_TYPE_VERIFY:
DPRINTF("Verify mode enabled");
ctx->restore.verify = true;
+ if ( !ctx->restore.verify_buf )
+ {
+ ctx->restore.verify_buf = malloc(MAX_BATCH_SIZE * PAGE_SIZE);
+ if ( !ctx->restore.verify_buf )
+ {
+ PERROR("Unable to allocate verify_buf");
+ rc = -1;
+ }
+ }
break;
case REC_TYPE_CHECKPOINT:
@@ -739,11 +871,19 @@ 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;
}
@@ -788,9 +928,12 @@ static int setup(struct xc_sr_context *c
ctx->restore.pp_pfns = malloc(MAX_BATCH_SIZE * sizeof(*ctx->restore.pp_pfns));
ctx->restore.pp_mfns = malloc(MAX_BATCH_SIZE * sizeof(*ctx->restore.pp_mfns));
ctx->restore.guest_data = malloc(MAX_BATCH_SIZE * sizeof(*ctx->restore.guest_data));
+ ctx->restore.iov = malloc(MAX_BATCH_SIZE * sizeof(*ctx->restore.iov));
+ ctx->restore.pages = malloc(MAX_BATCH_SIZE * sizeof(*ctx->restore.pages->pfn) + sizeof(*ctx->restore.pages));
if ( !ctx->restore.pfns || !ctx->restore.types || !ctx->restore.mfns ||
!ctx->restore.map_errs || !ctx->restore.pp_pfns ||
- !ctx->restore.pp_mfns || !ctx->restore.guest_data )
+ !ctx->restore.pp_mfns || !ctx->restore.guest_data ||
+ !ctx->restore.iov || !ctx->restore.pages )
{
ERROR("Unable to allocate memory");
rc = -1;
@@ -827,6 +970,8 @@ static void cleanup(struct xc_sr_context
free(ctx->restore.buffered_records);
free(ctx->restore.populated_pfns);
+ free(ctx->restore.pages);
+ free(ctx->restore.iov);
free(ctx->restore.guest_data);
free(ctx->restore.pp_mfns);
free(ctx->restore.pp_pfns);
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