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xen/libxc-sr-restore-read_record.patch

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From: Olaf Hering <olaf@aepfle.de>
Date: Mon, 26 Oct 2020 12:19:17 +0100
Subject: libxc sr restore read_record
tools: restore: split record processing
handle_page_data must be able to read directly into mapped guest memory.
This will avoid unneccesary memcpy calls for data which can be consumed verbatim.
Rearrange the code to allow decisions based on the incoming record.
This change is preparation for future changes in handle_page_data,
no change in behavior is intended.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
---
tools/libs/guest/xg_sr_common.c | 33 ++++++++++++---------
tools/libs/guest/xg_sr_common.h | 4 ++-
tools/libs/guest/xg_sr_restore.c | 49 ++++++++++++++++++++++----------
tools/libs/guest/xg_sr_save.c | 7 ++++-
4 files changed, 63 insertions(+), 30 deletions(-)
--- a/tools/libs/guest/xg_sr_common.c
+++ b/tools/libs/guest/xg_sr_common.c
@@ -91,26 +91,33 @@ int write_split_record(struct xc_sr_cont
return -1;
}
-int read_record(struct xc_sr_context *ctx, int fd, struct xc_sr_record *rec)
+int read_record_header(struct xc_sr_context *ctx, int fd, struct xc_sr_rhdr *rhdr)
{
xc_interface *xch = ctx->xch;
- struct xc_sr_rhdr rhdr;
- size_t datasz;
- if ( read_exact(fd, &rhdr, sizeof(rhdr)) )
+ if ( read_exact(fd, rhdr, sizeof(*rhdr)) )
{
PERROR("Failed to read Record Header from stream");
return -1;
}
- if ( rhdr.length > REC_LENGTH_MAX )
+ if ( rhdr->length > REC_LENGTH_MAX )
{
- ERROR("Record (0x%08x, %s) length %#x exceeds max (%#x)", rhdr.type,
- rec_type_to_str(rhdr.type), rhdr.length, REC_LENGTH_MAX);
+ ERROR("Record (0x%08x, %s) length %#x exceeds max (%#x)", rhdr->type,
+ rec_type_to_str(rhdr->type), rhdr->length, REC_LENGTH_MAX);
return -1;
}
- datasz = ROUNDUP(rhdr.length, REC_ALIGN_ORDER);
+ return 0;
+}
+
+int read_record_data(struct xc_sr_context *ctx, int fd, struct xc_sr_rhdr *rhdr,
+ struct xc_sr_record *rec)
+{
+ xc_interface *xch = ctx->xch;
+ size_t datasz;
+
+ datasz = ROUNDUP(rhdr->length, REC_ALIGN_ORDER);
if ( datasz )
{
@@ -119,7 +126,7 @@ int read_record(struct xc_sr_context *ct
if ( !rec->data )
{
ERROR("Unable to allocate %zu bytes for record data (0x%08x, %s)",
- datasz, rhdr.type, rec_type_to_str(rhdr.type));
+ datasz, rhdr->type, rec_type_to_str(rhdr->type));
return -1;
}
@@ -128,18 +135,18 @@ int read_record(struct xc_sr_context *ct
free(rec->data);
rec->data = NULL;
PERROR("Failed to read %zu bytes of data for record (0x%08x, %s)",
- datasz, rhdr.type, rec_type_to_str(rhdr.type));
+ datasz, rhdr->type, rec_type_to_str(rhdr->type));
return -1;
}
}
else
rec->data = NULL;
- rec->type = rhdr.type;
- rec->length = rhdr.length;
+ rec->type = rhdr->type;
+ rec->length = rhdr->length;
return 0;
-};
+}
static void __attribute__((unused)) build_assertions(void)
{
--- a/tools/libs/guest/xg_sr_common.h
+++ b/tools/libs/guest/xg_sr_common.h
@@ -458,7 +458,9 @@ static inline int write_record(struct xc
*
* On failure, the contents of the record structure are undefined.
*/
-int read_record(struct xc_sr_context *ctx, int fd, struct xc_sr_record *rec);
+int read_record_header(struct xc_sr_context *ctx, int fd, struct xc_sr_rhdr *rhdr);
+int read_record_data(struct xc_sr_context *ctx, int fd, struct xc_sr_rhdr *rhdr,
+ struct xc_sr_record *rec);
/*
* This would ideally be private in restore.c, but is needed by
--- a/tools/libs/guest/xg_sr_restore.c
+++ b/tools/libs/guest/xg_sr_restore.c
@@ -453,7 +453,7 @@ static int send_checkpoint_dirty_pfn_lis
return rc;
}
-static int process_record(struct xc_sr_context *ctx, struct xc_sr_record *rec);
+static int process_buffered_record(struct xc_sr_context *ctx, struct xc_sr_record *rec);
static int handle_checkpoint(struct xc_sr_context *ctx)
{
xc_interface *xch = ctx->xch;
@@ -492,7 +492,7 @@ static int handle_checkpoint(struct xc_s
for ( i = 0; i < ctx->restore.buffered_rec_num; i++ )
{
- rc = process_record(ctx, &ctx->restore.buffered_records[i]);
+ rc = process_buffered_record(ctx, &ctx->restore.buffered_records[i]);
if ( rc )
goto err;
}
@@ -553,10 +553,11 @@ static int handle_checkpoint(struct xc_s
return rc;
}
-static int buffer_record(struct xc_sr_context *ctx, struct xc_sr_record *rec)
+static int buffer_record(struct xc_sr_context *ctx, struct xc_sr_rhdr *rhdr)
{
xc_interface *xch = ctx->xch;
unsigned int new_alloc_num;
+ struct xc_sr_record rec;
struct xc_sr_record *p;
if ( ctx->restore.buffered_rec_num >= ctx->restore.allocated_rec_num )
@@ -574,8 +575,13 @@ static int buffer_record(struct xc_sr_co
ctx->restore.allocated_rec_num = new_alloc_num;
}
+ if ( read_record_data(ctx, ctx->fd, rhdr, &rec) )
+ {
+ return -1;
+ }
+
memcpy(&ctx->restore.buffered_records[ctx->restore.buffered_rec_num++],
- rec, sizeof(*rec));
+ &rec, sizeof(rec));
return 0;
}
@@ -606,7 +612,7 @@ int handle_static_data_end(struct xc_sr_
return rc;
}
-static int process_record(struct xc_sr_context *ctx, struct xc_sr_record *rec)
+static int process_buffered_record(struct xc_sr_context *ctx, struct xc_sr_record *rec)
{
xc_interface *xch = ctx->xch;
int rc = 0;
@@ -644,6 +650,19 @@ static int process_record(struct xc_sr_c
return rc;
}
+static int process_incoming_record_header(struct xc_sr_context *ctx, struct xc_sr_rhdr *rhdr)
+{
+ struct xc_sr_record rec;
+ int rc;
+
+ rc = read_record_data(ctx, ctx->fd, rhdr, &rec);
+ if ( rc )
+ return rc;
+
+ return process_buffered_record(ctx, &rec);
+}
+
+
static int setup(struct xc_sr_context *ctx)
{
xc_interface *xch = ctx->xch;
@@ -740,7 +759,7 @@ static void cleanup(struct xc_sr_context
static int restore(struct xc_sr_context *ctx)
{
xc_interface *xch = ctx->xch;
- struct xc_sr_record rec;
+ struct xc_sr_rhdr rhdr;
int rc, saved_rc = 0, saved_errno = 0;
IPRINTF("Restoring domain");
@@ -751,7 +770,7 @@ static int restore(struct xc_sr_context
do
{
- rc = read_record(ctx, ctx->fd, &rec);
+ rc = read_record_header(ctx, ctx->fd, &rhdr);
if ( rc )
{
if ( ctx->restore.buffer_all_records )
@@ -761,25 +780,25 @@ static int restore(struct xc_sr_context
}
if ( ctx->restore.buffer_all_records &&
- rec.type != REC_TYPE_END &&
- rec.type != REC_TYPE_CHECKPOINT )
+ rhdr.type != REC_TYPE_END &&
+ rhdr.type != REC_TYPE_CHECKPOINT )
{
- rc = buffer_record(ctx, &rec);
+ rc = buffer_record(ctx, &rhdr);
if ( rc )
goto err;
}
else
{
- rc = process_record(ctx, &rec);
+ rc = process_incoming_record_header(ctx, &rhdr);
if ( rc == RECORD_NOT_PROCESSED )
{
- if ( rec.type & REC_TYPE_OPTIONAL )
+ if ( rhdr.type & REC_TYPE_OPTIONAL )
DPRINTF("Ignoring optional record %#x (%s)",
- rec.type, rec_type_to_str(rec.type));
+ rhdr.type, rec_type_to_str(rhdr.type));
else
{
ERROR("Mandatory record %#x (%s) not handled",
- rec.type, rec_type_to_str(rec.type));
+ rhdr.type, rec_type_to_str(rhdr.type));
rc = -1;
goto err;
}
@@ -790,7 +809,7 @@ static int restore(struct xc_sr_context
goto err;
}
- } while ( rec.type != REC_TYPE_END );
+ } while ( rhdr.type != REC_TYPE_END );
remus_failover:
if ( ctx->stream_type == XC_STREAM_COLO )
--- a/tools/libs/guest/xg_sr_save.c
+++ b/tools/libs/guest/xg_sr_save.c
@@ -590,6 +590,7 @@ static int send_memory_live(struct xc_sr
static int colo_merge_secondary_dirty_bitmap(struct xc_sr_context *ctx)
{
xc_interface *xch = ctx->xch;
+ struct xc_sr_rhdr rhdr;
struct xc_sr_record rec;
uint64_t *pfns = NULL;
uint64_t pfn;
@@ -598,7 +599,11 @@ static int colo_merge_secondary_dirty_bi
DECLARE_HYPERCALL_BUFFER_SHADOW(unsigned long, dirty_bitmap,
&ctx->save.dirty_bitmap_hbuf);
- rc = read_record(ctx, ctx->save.recv_fd, &rec);
+ rc = read_record_header(ctx, ctx->save.recv_fd, &rhdr);
+ if ( rc )
+ goto err;
+
+ rc = read_record_data(ctx, ctx->save.recv_fd, &rhdr, &rec);
if ( rc )
goto err;
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