[Xen-changelog] [xen-unstable] xc_map_foreign_pages(), a convenient alternative to xc_map_foreign_batch()

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1189161550 -3600
# Node ID 9071521d48646d247efafcf230ea0a4a2b6f0efa
# Parent  0c14d0bf369eca202a4b35af8c9b23f47a2f1fec
xc_map_foreign_pages(), a convenient alternative to xc_map_foreign_batch()

xc_map_foreign_batch() can succeed partially.  It is awkward to use
when you're only interested in complete success.  Provide new
xc_map_foreign_pages() convenience function for that kind of use.
Also convert two obvious calls to use it.

Signed-off-by: Markus Armbruster <armbru@xxxxxxxxxx>
---
 tools/ioemu/hw/cirrus_vga.c |    2 +-
 tools/ioemu/vl.c            |    2 +-
 tools/libxc/xc_misc.c       |   33 +++++++++++++++++++++++++++++++++
 tools/libxc/xenctrl.h       |    8 ++++++++
 tools/xenfb/xenfb.c         |   10 ++--------
 5 files changed, 45 insertions(+), 10 deletions(-)

diff -r 0c14d0bf369e -r 9071521d4864 tools/ioemu/hw/cirrus_vga.c
--- a/tools/ioemu/hw/cirrus_vga.c       Fri Sep 07 11:30:18 2007 +0100
+++ b/tools/ioemu/hw/cirrus_vga.c       Fri Sep 07 11:39:10 2007 +0100
@@ -2565,7 +2565,7 @@ static void *set_vram_mapping(unsigned l
         return NULL;
     }
 
-    vram_pointer = xc_map_foreign_batch(xc_handle, domid,
+    vram_pointer = xc_map_foreign_pages(xc_handle, domid,
                                         PROT_READ|PROT_WRITE,
                                         extent_start, nr_extents);
     if (vram_pointer == NULL) {
diff -r 0c14d0bf369e -r 9071521d4864 tools/ioemu/vl.c
--- a/tools/ioemu/vl.c  Fri Sep 07 11:30:18 2007 +0100
+++ b/tools/ioemu/vl.c  Fri Sep 07 11:39:10 2007 +0100
@@ -6948,7 +6948,7 @@ static void qemu_remap_bucket(struct map
         j = ((i + BITS_PER_LONG) > (MCACHE_BUCKET_SIZE >> PAGE_SHIFT)) ?
             (MCACHE_BUCKET_SIZE >> PAGE_SHIFT) % BITS_PER_LONG : BITS_PER_LONG;
         while (j > 0)
-            word = (word << 1) | !(pfns[i + --j] & 0xF0000000UL);
+            word = (word << 1) | (((pfns[i + --j] >> 28) & 0xf) != 0xf);
         entry->valid_mapping[i / BITS_PER_LONG] = word;
     }
 }
diff -r 0c14d0bf369e -r 9071521d4864 tools/libxc/xc_misc.c
--- a/tools/libxc/xc_misc.c     Fri Sep 07 11:30:18 2007 +0100
+++ b/tools/libxc/xc_misc.c     Fri Sep 07 11:39:10 2007 +0100
@@ -224,6 +224,39 @@ int xc_hvm_set_pci_link_route(
     unlock_pages(&arg, sizeof(arg));
 
     return rc;
+}
+
+void *xc_map_foreign_pages(int xc_handle, uint32_t dom, int prot,
+                           const xen_pfn_t *arr, int num)
+{
+    xen_pfn_t *pfn;
+    void *res;
+    int i;
+
+    pfn = malloc(num * sizeof(*pfn));
+    if (!pfn)
+        return NULL;
+    memcpy(pfn, arr, num * sizeof(*pfn));
+
+    res = xc_map_foreign_batch(xc_handle, dom, prot, pfn, num);
+    if (res) {
+        for (i = 0; i < num; i++) {
+            if ((pfn[i] & 0xF0000000UL) == 0xF0000000UL) {
+                /*
+                 * xc_map_foreign_batch() doesn't give us an error
+                 * code, so we have to make one up.  May not be the
+                 * appropriate one.
+                 */
+                errno = EINVAL;
+                munmap(res, num * PAGE_SIZE);
+                res = NULL;
+                break;
+            }
+        }
+    }
+
+    free(pfn);
+    return res;
 }
 
 /*
diff -r 0c14d0bf369e -r 9071521d4864 tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h     Fri Sep 07 11:30:18 2007 +0100
+++ b/tools/libxc/xenctrl.h     Fri Sep 07 11:39:10 2007 +0100
@@ -646,6 +646,14 @@ void *xc_map_foreign_range(int xc_handle
                             int size, int prot,
                             unsigned long mfn );
 
+void *xc_map_foreign_pages(int xc_handle, uint32_t dom, int prot,
+                           const xen_pfn_t *arr, int num );
+
+/**
+ * Like xc_map_foreign_pages(), except it can succeeed partially.
+ * When a page cannot be mapped, its PFN in @arr is or'ed with
+ * 0xF0000000 to indicate the error.
+ */
 void *xc_map_foreign_batch(int xc_handle, uint32_t dom, int prot,
                            xen_pfn_t *arr, int num );
 
diff -r 0c14d0bf369e -r 9071521d4864 tools/xenfb/xenfb.c
--- a/tools/xenfb/xenfb.c       Fri Sep 07 11:30:18 2007 +0100
+++ b/tools/xenfb/xenfb.c       Fri Sep 07 11:39:10 2007 +0100
@@ -398,21 +398,15 @@ static int xenfb_map_fb(struct xenfb_pri
        if (!pgmfns || !fbmfns)
                goto out;
 
-       /*
-        * Bug alert: xc_map_foreign_batch() can fail partly and
-        * return a non-null value.  This is a design flaw.  When it
-        * happens, we happily continue here, and later crash on
-        * access.
-        */
        xenfb_copy_mfns(mode, n_fbdirs, pgmfns, pd);
-       map = xc_map_foreign_batch(xenfb->xc, domid,
+       map = xc_map_foreign_pages(xenfb->xc, domid,
                                   PROT_READ, pgmfns, n_fbdirs);
        if (map == NULL)
                goto out;
        xenfb_copy_mfns(mode, n_fbmfns, fbmfns, map);
        munmap(map, n_fbdirs * XC_PAGE_SIZE);
 
-       xenfb->pub.pixels = xc_map_foreign_batch(xenfb->xc, domid,
+       xenfb->pub.pixels = xc_map_foreign_pages(xenfb->xc, domid,
                                PROT_READ | PROT_WRITE, fbmfns, n_fbmfns);
        if (xenfb->pub.pixels == NULL)
                goto out;

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