libxc: do not align/lock buffers which do not need it

On restore:

region_mfn is passed to xc_map_foreign_range and
xc_map_foreign_bulk. In both cases the buffer is accessed from the
ioctl handler in the kernel and not from any hypercall. Therefore
normal copy_{to,from}_user handling in the kernel will cope with any
faulting access.

p2m_batch is passed to xc_domain_memory_populate_physmap which takes
care of bouncing the buffer already.

On save:

pfn_type is passed to xc_map_foreign_bulk which does not need locking
as per region_mfn above.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Ian Jackson <ian.jackson.citrix.com>

1 files changed, 2 insertions, 16 deletions

diff --git a/tools/libxc/xc_domain_restore.c b/tools/libxc/xc_domain_restore.c
index 047cd774a7..5ac2de5445 100644
--- a/tools/libxc/xc_domain_restore.c
+++ b/tools/libxc/xc_domain_restore.c
@@ -1172,10 +1172,8 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
     ctx->p2m   = calloc(dinfo->p2m_size, sizeof(xen_pfn_t));
     pfn_type   = calloc(dinfo->p2m_size, sizeof(unsigned long));
 
-    region_mfn = xc_memalign(PAGE_SIZE, ROUNDUP(
-                              MAX_BATCH_SIZE * sizeof(xen_pfn_t), PAGE_SHIFT));
-    ctx->p2m_batch = xc_memalign(
-        PAGE_SIZE, ROUNDUP(MAX_BATCH_SIZE * sizeof(xen_pfn_t), PAGE_SHIFT));
+    region_mfn = malloc(ROUNDUP(MAX_BATCH_SIZE * sizeof(xen_pfn_t), PAGE_SHIFT));
+    ctx->p2m_batch = malloc(ROUNDUP(MAX_BATCH_SIZE * sizeof(xen_pfn_t), PAGE_SHIFT));
 
     if ( (ctx->p2m == NULL) || (pfn_type == NULL) ||
          (region_mfn == NULL) || (ctx->p2m_batch == NULL) )
@@ -1190,18 +1188,6 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
     memset(ctx->p2m_batch, 0,
            ROUNDUP(MAX_BATCH_SIZE * sizeof(xen_pfn_t), PAGE_SHIFT)); 
 
-    if ( lock_pages(xch, region_mfn, sizeof(xen_pfn_t) * MAX_BATCH_SIZE) )
-    {
-        PERROR("Could not lock region_mfn");
-        goto out;
-    }
-
-    if ( lock_pages(xch, ctx->p2m_batch, sizeof(xen_pfn_t) * MAX_BATCH_SIZE) )
-    {
-        ERROR("Could not lock p2m_batch");
-        goto out;
-    }
-
     /* Get the domain's shared-info frame. */
     domctl.cmd = XEN_DOMCTL_getdomaininfo;
     domctl.domain = (domid_t)dom;