[Xen-devel] [PATCH 24 of 25] libxc: do not align/lock buffers which do not need it

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1287650255 -3600
# Node ID 42caa87197dfe69901d4d20c6432b5914b62ac07
# Parent  970a248771788f44fac6e4139972deb3af40a280
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@xxxxxxxxxx>

diff -r 970a24877178 -r 42caa87197df tools/libxc/xc_domain_restore.c
--- a/tools/libxc/xc_domain_restore.c   Thu Oct 21 09:37:35 2010 +0100
+++ b/tools/libxc/xc_domain_restore.c   Thu Oct 21 09:37:35 2010 +0100
@@ -1172,10 +1172,8 @@ int xc_domain_restore(xc_interface *xch,
     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) )
@@ -1189,18 +1187,6 @@ int xc_domain_restore(xc_interface *xch,
            ROUNDUP(MAX_BATCH_SIZE * sizeof(xen_pfn_t), PAGE_SHIFT)); 
     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;
diff -r 970a24877178 -r 42caa87197df tools/libxc/xc_domain_save.c
--- a/tools/libxc/xc_domain_save.c      Thu Oct 21 09:37:35 2010 +0100
+++ b/tools/libxc/xc_domain_save.c      Thu Oct 21 09:37:35 2010 +0100
@@ -1071,8 +1071,7 @@ int xc_domain_save(xc_interface *xch, in
 
     analysis_phase(xch, dom, ctx, HYPERCALL_BUFFER(to_skip), 0);
 
-    pfn_type   = xc_memalign(PAGE_SIZE, ROUNDUP(
-                              MAX_BATCH_SIZE * sizeof(*pfn_type), PAGE_SHIFT));
+    pfn_type   = malloc(ROUNDUP(MAX_BATCH_SIZE * sizeof(*pfn_type), 
PAGE_SHIFT));
     pfn_batch  = calloc(MAX_BATCH_SIZE, sizeof(*pfn_batch));
     pfn_err    = malloc(MAX_BATCH_SIZE * sizeof(*pfn_err));
     if ( (pfn_type == NULL) || (pfn_batch == NULL) || (pfn_err == NULL) )
@@ -1083,12 +1082,6 @@ int xc_domain_save(xc_interface *xch, in
     }
     memset(pfn_type, 0,
            ROUNDUP(MAX_BATCH_SIZE * sizeof(*pfn_type), PAGE_SHIFT));
-
-    if ( lock_pages(xch, pfn_type, MAX_BATCH_SIZE * sizeof(*pfn_type)) )
-    {
-        PERROR("Unable to lock pfn_type array");
-        goto out;
-    }
 
     /* Setup the mfn_to_pfn table mapping */
     if ( !(ctx->live_m2p = xc_map_m2p(xch, ctx->max_mfn, PROT_READ, 
&ctx->m2p_mfn0)) )

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