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Re: [Xen-devel] [PATCH v5 RFC 14/14] tools/libxc: noarch restore code



On 06/12/2014 02:14 AM, Andrew Cooper wrote:
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxxx>
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
  tools/libxc/saverestore/common.h  |    6 +
  tools/libxc/saverestore/restore.c |  556 ++++++++++++++++++++++++++++++++++++-
  2 files changed, 561 insertions(+), 1 deletion(-)

diff --git a/tools/libxc/saverestore/common.h b/tools/libxc/saverestore/common.h
index e16e0de..2d44961 100644
--- a/tools/libxc/saverestore/common.h
+++ b/tools/libxc/saverestore/common.h
@@ -292,6 +292,12 @@ static inline int write_record(struct context *ctx, struct 
record *rec)
      return write_split_record(ctx, rec, NULL, 0);
  }

...snip...
+/*
+ * Given a list of pfns, their types, and a block of page data from the
+ * stream, populate and record their types, map the relevent subset and copy
+ * the data into the guest.
+ */
+static int process_page_data(struct context *ctx, unsigned count,
+                             xen_pfn_t *pfns, uint32_t *types, void *page_data)
+{
+    xc_interface *xch = ctx->xch;
+    xen_pfn_t *mfns = malloc(count * sizeof(*mfns));
+    int *map_errs = malloc(count * sizeof(*map_errs));
+    int rc = -1;
+    void *mapping = NULL, *guest_page = NULL;
+    unsigned i,    /* i indexes the pfns from the record. */
+        j,         /* j indexes the subset of pfns we decide to map. */
+        nr_pages;
+
+    if ( !mfns || !map_errs )
+    {
+        ERROR("Failed to allocate %zu bytes to process page data",
+              count * (sizeof(*mfns) + sizeof(*map_errs)));
+        goto err;
+    }
+
+    rc = populate_pfns(ctx, count, pfns, types);
+    if ( rc )
+    {
+        ERROR("Failed to populate pfns for batch of %u pages", count);
+        goto err;
+    }
+    rc = -1;
+
+    for ( i = 0, nr_pages = 0; i < count; ++i )
+    {
+        ctx->ops.set_page_type(ctx, pfns[i], types[i]);
+
+        switch ( types[i] )
+        {
+        case XEN_DOMCTL_PFINFO_NOTAB:
+
+        case XEN_DOMCTL_PFINFO_L1TAB:
+        case XEN_DOMCTL_PFINFO_L1TAB | XEN_DOMCTL_PFINFO_LPINTAB:
+
+        case XEN_DOMCTL_PFINFO_L2TAB:
+        case XEN_DOMCTL_PFINFO_L2TAB | XEN_DOMCTL_PFINFO_LPINTAB:
+
+        case XEN_DOMCTL_PFINFO_L3TAB:
+        case XEN_DOMCTL_PFINFO_L3TAB | XEN_DOMCTL_PFINFO_LPINTAB:
+
+        case XEN_DOMCTL_PFINFO_L4TAB:
+        case XEN_DOMCTL_PFINFO_L4TAB | XEN_DOMCTL_PFINFO_LPINTAB:
+
+            mfns[nr_pages++] = ctx->ops.pfn_to_gfn(ctx, pfns[i]);
+            break;
+        }
+
+    }
+
+    if ( nr_pages > 0 )
+    {
+        mapping = guest_page = xc_map_foreign_bulk(
+            xch, ctx->domid, PROT_READ | PROT_WRITE,
+            mfns, map_errs, nr_pages);
+        if ( !mapping )
+        {
+            PERROR("Unable to map %u mfns for %u pages of data",
+                   nr_pages, count);
+            goto err;
+        }
+    }
+
+    for ( i = 0, j = 0; i < count; ++i )
+    {
+        switch ( types[i] )
+        {
+        case XEN_DOMCTL_PFINFO_XTAB:
+        case XEN_DOMCTL_PFINFO_BROKEN:
+        case XEN_DOMCTL_PFINFO_XALLOC:
+            /* No page data to deal with. */
+            continue;
+        }
+
+        if ( map_errs[j] )
+        {
+            ERROR("Mapping pfn %lx (mfn %lx, type %#"PRIx32")failed with %d",
+                  pfns[i], mfns[j], types[i], map_errs[j]);

missing rc = -1 here, rc could be 0 because in the following called:
    rc = ctx->restore.ops.localise_page(ctx, types[i], guest_page);

+            goto err;
+        }
+
+        memcpy(guest_page, page_data, PAGE_SIZE);
+
+        /* Undo page normalisation done by the saver. */
+        rc = ctx->restore.ops.localise_page(ctx, types[i], guest_page);
+        if ( rc )
+        {
+            DPRINTF("Failed to localise");
+            goto err;
+        }
+
+        ++j;
+        guest_page += PAGE_SIZE;
+        page_data += PAGE_SIZE;
+    }
+
+    rc = 0;
+
+ err:
+    if ( mapping )
+        munmap(mapping, nr_pages * PAGE_SIZE);
+
+    free(map_errs);
+    free(mfns);
+
+    return rc;
+}
+
+/*
+ * Validate a PAGE_DATA record from the stream, and pass the results to
+ * process_page_data() to actually perform the legwork.
+ */
+static int handle_page_data(struct context *ctx, struct record *rec)
+{
+    xc_interface *xch = ctx->xch;
+    struct rec_page_data_header *pages = rec->data;
+    unsigned i, pages_of_data = 0;
+    int rc = -1;
+
+    xen_pfn_t *pfns = NULL, pfn;
+    uint32_t *types = NULL, type;
+
+    if ( rec->length < sizeof(*pages) )
+    {
+        ERROR("PAGE_DATA record truncated: length %"PRIu32", min %zu",
+              rec->length, sizeof(*pages));
+        goto err;
+    }
+    else if ( pages->count < 1 )
+    {
+        ERROR("Expected at least 1 pfn in PAGE_DATA record");
+        goto err;
+    }
+    else if ( rec->length < sizeof(*pages) + (pages->count * sizeof(uint64_t)) 
)
+    {
+        ERROR("PAGE_DATA record (length %"PRIu32") too short to contain %"
+              PRIu32" pfns worth of information", rec->length, pages->count);
+        goto err;
+    }
+
+    pfns = malloc(pages->count * sizeof(*pfns));
+    types = malloc(pages->count * sizeof(*types));
+    if ( !pfns || !types )
+    {
+        ERROR("Unable to allocate enough memory for %"PRIu32" pfns",
+              pages->count);
+        goto err;
+    }
+
+    for ( i = 0; i < pages->count; ++i )
+    {
+        pfn = pages->pfn[i] & PAGE_DATA_PFN_MASK;
+        if ( !ctx->ops.pfn_is_valid(ctx, pfn) )
+        {
+            ERROR("pfn %#lx (index %u) outside domain maximum", pfn, i);
+            goto err;
+        }
+
+        type = (pages->pfn[i] & PAGE_DATA_TYPE_MASK) >> 32;
+        if ( ((type >> XEN_DOMCTL_PFINFO_LTAB_SHIFT) >= 5) &&
+             ((type >> XEN_DOMCTL_PFINFO_LTAB_SHIFT) <= 8) )
+        {
+            ERROR("Invalid type %#"PRIx32" for pfn %#lx (index %u)", type, 
pfn, i);
+            goto err;
+        }
+        else if ( type < XEN_DOMCTL_PFINFO_BROKEN )
+            /* NOTAB and all L1 thru L4 tables (including pinned) should have
+             * a page worth of data in the record. */
+            pages_of_data++;
+
+        pfns[i] = pfn;
+        types[i] = type;
+    }
+
+    if ( rec->length != (sizeof(*pages) +
+                         (sizeof(uint64_t) * pages->count) +
+                         (PAGE_SIZE * pages_of_data)) )
+    {
+        ERROR("PAGE_DATA record wrong size: length %"PRIu32", expected "
+              "%zu + %zu + %zu", rec->length, sizeof(*pages),
+              (sizeof(uint64_t) * pages->count), (PAGE_SIZE * pages_of_data));
+        goto err;
+    }
+
+    rc = process_page_data(ctx, pages->count, pfns, types,
+                           &pages->pfn[pages->count]);
+ err:
+    free(types);
+    free(pfns);
+
+    return rc;
+}
+
+/*
+ * Restore a domain.
+ */
+static int restore(struct context *ctx)
+{
+    xc_interface *xch = ctx->xch;
+    struct record rec;
+    int rc, saved_rc = 0, saved_errno = 0;
+
+    IPRINTF("Restoring domain");
+
+    rc = ctx->restore.ops.setup(ctx);
+    if ( rc )
+        goto err;
+
+    do
+    {
+        rc = read_record(ctx, &rec);
+        if ( rc )
+            goto err;
+
+        switch ( rec.type )
+        {
+        case REC_TYPE_END:
+            DPRINTF("End record");
+            break;
+
+        case REC_TYPE_PAGE_DATA:
+            rc = handle_page_data(ctx, &rec);
+            break;
+
+        default:
+            rc = ctx->restore.ops.process_record(ctx, &rec);
+            break;
+        }
+
+        free(rec.data);
+        if ( rc )
+            goto err;
+
+    } while ( rec.type != REC_TYPE_END );
+
+    rc = ctx->restore.ops.stream_complete(ctx);
+    if ( rc )
+        goto err;
+
+    IPRINTF("Restore successful");
+    goto done;
+
+ err:
+    saved_errno = errno;
+    saved_rc = rc;
+    PERROR("Restore failed");
+
+ done:
+    free(ctx->restore.populated_pfns);
+    rc = ctx->restore.ops.cleanup(ctx);
+    if ( rc )
+        PERROR("Failed to clean up");
+
+    if ( saved_rc )
+    {
+        rc = saved_rc;
+        errno = saved_errno;
+    }
+
+    return rc;
+}
+
  int xc_domain_restore2(xc_interface *xch, int io_fd, uint32_t dom,
                         unsigned int store_evtchn, unsigned long *store_mfn,
                         domid_t store_domid, unsigned int console_evtchn,
@@ -8,8 +502,68 @@ int xc_domain_restore2(xc_interface *xch, int io_fd, 
uint32_t dom,
                         int checkpointed_stream,
                         struct restore_callbacks *callbacks)
  {
+    struct context ctx =
+        {
+            .xch = xch,
+            .fd = io_fd,
+        };
+
+    /* GCC 4.4 (of CentOS 6.x vintage) can' t initialise anonymous unions :( */
+    ctx.restore.console_evtchn = console_evtchn;
+    ctx.restore.console_domid = console_domid;
+    ctx.restore.xenstore_evtchn = store_evtchn;
+    ctx.restore.xenstore_domid = store_domid;
+    ctx.restore.callbacks = callbacks;
+
      IPRINTF("In experimental %s", __func__);
-    return -1;
+
+    if ( xc_domain_getinfo(xch, dom, 1, &ctx.dominfo) != 1 )
+    {
+        PERROR("Failed to get domain info");
+        return -1;
+    }
+
+    if ( ctx.dominfo.domid != dom )
+    {
+        ERROR("Domain %d does not exist", dom);
+        return -1;
+    }
+
+    ctx.domid = dom;
+    IPRINTF("Restoring domain %d", dom);
+
+    if ( read_headers(&ctx) )
+        return -1;
+
+    if ( ctx.dominfo.hvm )
+    {
+        ctx.ops = common_ops_x86_hvm;
+        ctx.restore.ops = restore_ops_x86_hvm;
+        if ( restore(&ctx) )
+            return -1;
+    }
+    else
+    {
+        ctx.ops = common_ops_x86_pv;
+        ctx.restore.ops = restore_ops_x86_pv;
+        if ( restore(&ctx) )
+            return -1;
+    }
+
+    DPRINTF("XenStore: mfn %#lx, dom %d, evt %u",
+            ctx.restore.xenstore_mfn,
+            ctx.restore.xenstore_domid,
+            ctx.restore.xenstore_evtchn);
+
+    DPRINTF("Console: mfn %#lx, dom %d, evt %u",
+            ctx.restore.console_mfn,
+            ctx.restore.console_domid,
+            ctx.restore.console_evtchn);
+
+    *console_mfn = ctx.restore.console_mfn;
+    *store_mfn = ctx.restore.xenstore_mfn;
+
+    return 0;
  }

  /*


--
Thanks,
Yang.

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