[PATCH v7 6/9] tools/libxc: split restore handler handle_shared_info() functionality

[Paul Durrant <paul@xxxxxxx>]

From: Paul Durrant <pdurrant@xxxxxxxxxx>

The code is invoked when a SHARED_INFO record is processed but actually
performs two functions:

[1] Copy the 'vcpu_info' and 'arch' substructures from the record into the
    new domain's shared_info
[2] Clear out any pending event channel state, mask all channels and also
    clear 'arch.pfn_to_mfn_frame_list_list'

To facilitate deprecation of the SHARED_INFO record in version 4 of the
migration stream, this patch splits the functionality, leaving [1] in
handle_shared_info() and adding update_shared_info() (called from
x86_pv_stream_complete()) to deal with [2].

Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wl@xxxxxxx>

v7:
 - New in v7
---
 tools/libxc/xc_sr_restore_x86_pv.c | 31 +++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/tools/libxc/xc_sr_restore_x86_pv.c 
b/tools/libxc/xc_sr_restore_x86_pv.c
index d086271efb..1ed8cc66ca 100644
--- a/tools/libxc/xc_sr_restore_x86_pv.c
+++ b/tools/libxc/xc_sr_restore_x86_pv.c
@@ -880,7 +880,6 @@ static int handle_shared_info(struct xc_sr_context *ctx,
                               struct xc_sr_record *rec)
 {
     xc_interface *xch = ctx->xch;
-    unsigned int i;
     int rc = -1;
     shared_info_any_t *guest_shinfo = NULL;
     const shared_info_any_t *old_shinfo = rec->data;
@@ -911,6 +910,32 @@ static int handle_shared_info(struct xc_sr_context *ctx,
     MEMCPY_FIELD(guest_shinfo, old_shinfo, vcpu_info, ctx->x86.pv.width);
     MEMCPY_FIELD(guest_shinfo, old_shinfo, arch, ctx->x86.pv.width);
 
+    rc = 0;
+
+ err:
+    if ( guest_shinfo )
+        munmap(guest_shinfo, PAGE_SIZE);
+
+    return rc;
+}
+
+static int update_shared_info(struct xc_sr_context *ctx)
+{
+    xc_interface *xch = ctx->xch;
+    unsigned int i;
+    int rc = -1;
+    shared_info_any_t *guest_shinfo = NULL;
+
+    guest_shinfo = xc_map_foreign_range(
+        xch, ctx->domid, PAGE_SIZE, PROT_READ | PROT_WRITE,
+        ctx->dominfo.shared_info_frame);
+    if ( !guest_shinfo )
+    {
+        PERROR("Failed to map Shared Info at mfn %#lx",
+               ctx->dominfo.shared_info_frame);
+        goto err;
+    }
+
     SET_FIELD(guest_shinfo, arch.pfn_to_mfn_frame_list_list,
               0, ctx->x86.pv.width);
 
@@ -1122,6 +1147,10 @@ static int x86_pv_stream_complete(struct xc_sr_context 
*ctx)
     xc_interface *xch = ctx->xch;
     int rc;
 
+    rc = update_shared_info(ctx);
+    if ( rc )
+        return rc;
+
     rc = update_vcpu_context(ctx);
     if ( rc )
         return rc;
-- 
2.20.1