tools/libxc: x86 PV restore code

Restore the x86 PV specific parts.  The X86_PV_INFO, the P2M_FRAMES,
SHARED_INFO, and VCPU context records.

The localise_page callback is called from the common PAGE_DATA code to convert
PFNs in page tables to MFNs.

Page tables are pinned and the guest's P2M is updated when the stream is
complete.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>

tools/libxc/Makefile

@@ -57,6 +57,7 @@ GUEST_SRCS-y += xc_domain_restore.c xc_domain_save.c
 GUEST_SRCS-y += xc_sr_common.c
 GUEST_SRCS-$(CONFIG_X86) += xc_sr_common_x86.c
 GUEST_SRCS-$(CONFIG_X86) += xc_sr_common_x86_pv.c
+GUEST_SRCS-$(CONFIG_X86) += xc_sr_restore_x86_pv.c
 GUEST_SRCS-$(CONFIG_X86) += xc_sr_save_x86_pv.c
 GUEST_SRCS-y += xc_sr_restore.c
 GUEST_SRCS-y += xc_sr_save.c

tools/libxc/xc_sr_common.h

@@ -287,6 +287,8 @@ struct xc_sr_context
 
 extern struct xc_sr_save_ops save_ops_x86_pv;
 
+extern struct xc_sr_restore_ops restore_ops_x86_pv;
+
 struct xc_sr_record
 {
     uint32_t type;
@@ -321,6 +323,14 @@ static inline int write_record(struct xc_sr_context *ctx,
     return write_split_record(ctx, rec, NULL, 0);
 }
 
+/*
+ * This would ideally be private in restore.c, but is needed by
+ * x86_pv_localise_page() if we receive pagetables frames ahead of the
+ * contents of the frames they point at.
+ */
+int populate_pfns(struct xc_sr_context *ctx, unsigned count,
+                  const xen_pfn_t *original_pfns, const uint32_t *types);
+
 #endif
 /*
  * Local variables:

tools/libxc/xc_sr_restore.c

@@ -1,5 +1,130 @@
 #include "xc_sr_common.h"
 
+/*
+ * Is a pfn populated?
+ */
+static bool pfn_is_populated(const struct xc_sr_context *ctx, xen_pfn_t pfn)
+{
+    if ( pfn > ctx->restore.max_populated_pfn )
+        return false;
+    return test_bit(pfn, ctx->restore.populated_pfns);
+}
+
+/*
+ * Set a pfn as populated, expanding the tracking structures if needed. To
+ * avoid realloc()ing too excessivly, the size increased to the nearest power
+ * of two large enough to contain the required pfn.
+ */
+static int pfn_set_populated(struct xc_sr_context *ctx, xen_pfn_t pfn)
+{
+    xc_interface *xch = ctx->xch;
+
+    if ( pfn > ctx->restore.max_populated_pfn )
+    {
+        xen_pfn_t new_max;
+        size_t old_sz, new_sz;
+        unsigned long *p;
+
+        /* Round up to the nearest power of two larger than pfn, less 1. */
+        new_max = pfn;
+        new_max |= new_max >> 1;
+        new_max |= new_max >> 2;
+        new_max |= new_max >> 4;
+        new_max |= new_max >> 8;
+        new_max |= new_max >> 16;
+#ifdef __x86_64__
+        new_max |= new_max >> 32;
+#endif
+
+        old_sz = bitmap_size(ctx->restore.max_populated_pfn + 1);
+        new_sz = bitmap_size(new_max + 1);
+        p = realloc(ctx->restore.populated_pfns, new_sz);
+        if ( !p )
+        {
+            ERROR("Failed to realloc populated bitmap");
+            errno = ENOMEM;
+            return -1;
+        }
+
+        memset((uint8_t *)p + old_sz, 0x00, new_sz - old_sz);
+
+        ctx->restore.populated_pfns    = p;
+        ctx->restore.max_populated_pfn = new_max;
+    }
+
+    set_bit(pfn, ctx->restore.populated_pfns);
+
+    return 0;
+}
+
+/*
+ * Given a set of pfns, obtain memory from Xen to fill the physmap for the
+ * unpopulated subset.  If types is NULL, no page typechecking is performed
+ * and all unpopulated pfns are populated.
+ */
+int populate_pfns(struct xc_sr_context *ctx, unsigned count,
+                  const xen_pfn_t *original_pfns, const uint32_t *types)
+{
+    xc_interface *xch = ctx->xch;
+    xen_pfn_t *mfns = malloc(count * sizeof(*mfns)),
+        *pfns = malloc(count * sizeof(*pfns));
+    unsigned i, nr_pfns = 0;
+    int rc = -1;
+
+    if ( !mfns || !pfns )
+    {
+        ERROR("Failed to allocate %zu bytes for populating the physmap",
+              2 * count * sizeof(*mfns));
+        goto err;
+    }
+
+    for ( i = 0; i < count; ++i )
+    {
+        if ( (!types || (types &&
+                         (types[i] != XEN_DOMCTL_PFINFO_XTAB &&
+                          types[i] != XEN_DOMCTL_PFINFO_BROKEN))) &&
+             !pfn_is_populated(ctx, original_pfns[i]) )
+        {
+            pfns[nr_pfns] = mfns[nr_pfns] = original_pfns[i];
+            ++nr_pfns;
+        }
+    }
+
+    if ( nr_pfns )
+    {
+        rc = xc_domain_populate_physmap_exact(
+            xch, ctx->domid, nr_pfns, 0, 0, mfns);
+        if ( rc )
+        {
+            PERROR("Failed to populate physmap");
+            goto err;
+        }
+
+        for ( i = 0; i < nr_pfns; ++i )
+        {
+            if ( mfns[i] == INVALID_MFN )
+            {
+                ERROR("Populate physmap failed for pfn %u", i);
+                rc = -1;
+                goto err;
+            }
+
+            rc = pfn_set_populated(ctx, pfns[i]);
+            if ( rc )
+                goto err;
+            ctx->restore.ops.set_gfn(ctx, pfns[i], mfns[i]);
+        }
+    }
+
+    rc = 0;
+
+ err:
+    free(pfns);
+    free(mfns);
+
+    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,