[Xen-devel] [PATCH] Synchronize privcmd header constants

[Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>]

 tools/include/xen-sys/Linux/privcmd.h |   3 +++
 tools/libxc/xc_linux_osdep.c          |  10 +++++-----
 xen/include/public/domctl.h           |   1 -
 3 files changed, 8 insertions(+), 6 deletions(-)


Since Linux's git commit ceb90fa0a8008059ecbbf9114cb89dc71a730bb6, the
privcmd.h interface between Linux and libxc specifies two new constants,
PRIVCMD_MMAPBATCH_MFN_ERROR and PRIVCMD_MMAPBATCH_PAGED_ERROR. These constants
represent the error codes encoded in the top nibble of an mfn slot passed to
the legacy MMAPBATCH ioctl.

In particular, libxenctrl checks for the equivalent of the latter constant when
dealing with paged out frames that might be the target of a foreign map.

Previously, the relevant constant was defined in the domctl hypervisor
interface header (XEN_DOMCTL_PFINFO_PAGEDTAB). Because this top-nibble encoding
is a contract between the dom0 kernel and libxc, a domctl.h definition is
misplaced.

- Sync the privcmd.h header to that now available in upstream Linux
- Update libxc appropriately
- Remove the unnecessary constant in domctl.h

Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>

diff -r 4eed5e64544f -r 5171750d133e tools/include/xen-sys/Linux/privcmd.h
--- a/tools/include/xen-sys/Linux/privcmd.h
+++ b/tools/include/xen-sys/Linux/privcmd.h
@@ -64,6 +64,9 @@ typedef struct privcmd_mmapbatch {
        xen_pfn_t __user *arr; /* array of mfns - top nibble set on err */
 } privcmd_mmapbatch_t; 
 
+#define PRIVCMD_MMAPBATCH_MFN_ERROR     0xf0000000U
+#define PRIVCMD_MMAPBATCH_PAGED_ERROR   0x80000000U
+
 typedef struct privcmd_mmapbatch_v2 {
        unsigned int num; /* number of pages to populate */
        domid_t dom;      /* target domain */
diff -r 4eed5e64544f -r 5171750d133e tools/libxc/xc_linux_osdep.c
--- a/tools/libxc/xc_linux_osdep.c
+++ b/tools/libxc/xc_linux_osdep.c
@@ -129,7 +129,7 @@ static int xc_map_foreign_batch_single(i
 
     do
     {
-        *mfn ^= XEN_DOMCTL_PFINFO_PAGEDTAB;
+        *mfn ^= PRIVCMD_MMAPBATCH_PAGED_ERROR;
         usleep(100);
         rc = ioctl(fd, IOCTL_PRIVCMD_MMAPBATCH, &ioctlx);
     }
@@ -166,8 +166,8 @@ static void *linux_privcmd_map_foreign_b
 
         for ( i = 0; i < num; i++ )
         {
-            if ( (arr[i] & XEN_DOMCTL_PFINFO_LTAB_MASK) ==
-                 XEN_DOMCTL_PFINFO_PAGEDTAB )
+            if ( (arr[i] & PRIVCMD_MMAPBATCH_MFN_ERROR) ==
+                           PRIVCMD_MMAPBATCH_PAGED_ERROR )
             {
                 unsigned long paged_addr = (unsigned long)addr + (i << 
XC_PAGE_SHIFT);
                 rc = xc_map_foreign_batch_single(fd, dom, &arr[i],
@@ -323,12 +323,12 @@ static void *linux_privcmd_map_foreign_b
             default:
                 err[i] = -EINVAL;
                 continue;
-            case XEN_DOMCTL_PFINFO_PAGEDTAB:
+            case PRIVCMD_MMAPBATCH_PAGED_ERROR:
                 if ( rc != -ENOENT )
                 {
                     err[i] = rc ?: -EINVAL;
                     continue;
-                 }
+                }
                 rc = xc_map_foreign_batch_single(fd, dom, pfn + i,
                         (unsigned long)addr + ((unsigned 
long)i<<XC_PAGE_SHIFT));
                 if ( rc < 0 )
diff -r 4eed5e64544f -r 5171750d133e xen/include/public/domctl.h
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -135,7 +135,6 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_getme
 #define XEN_DOMCTL_PFINFO_LPINTAB (0x1U<<31)
 #define XEN_DOMCTL_PFINFO_XTAB    (0xfU<<28) /* invalid page */
 #define XEN_DOMCTL_PFINFO_XALLOC  (0xeU<<28) /* allocate-only page */
-#define XEN_DOMCTL_PFINFO_PAGEDTAB (0x8U<<28)
 #define XEN_DOMCTL_PFINFO_LTAB_MASK (0xfU<<28)
 
 struct xen_domctl_getpageframeinfo {

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