hypervisor/xen/tools: Remove the XENMEM_get_oustanding_pages and provide the data via xc_phys_info

During the review of the patches it was noticed that there exists
a race wherein the 'free_memory' value consists of information from
two hypercalls. That is the XEN_SYSCTL_physinfo and XENMEM_get_outstanding_pages.

The free memory the host has available for guest is the difference between
the 'free_pages' (from XEN_SYSCTL_physinfo) and 'outstanding_pages'. As they
are two hypercalls many things can happen in between the execution of them.

This patch resolves this by eliminating the XENMEM_get_outstanding_pages
hypercall and providing the free_pages and outstanding_pages information
via the xc_phys_info structure.

It also removes the XSM hooks and adds locking as needed.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Reviewed-by: Tim Deegan <tim@xen.org>
Acked-by: Keir Fraser <keir.xen@gmail.com>

4 files changed, 5 insertions, 28 deletions

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index bc91fd5abf..ee1fa9cf8c 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -3942,6 +3942,7 @@ int libxl_get_physinfo(libxl_ctx *ctx, libxl_physinfo *physinfo)
     physinfo->total_pages = xcphysinfo.total_pages;
     physinfo->free_pages = xcphysinfo.free_pages;
     physinfo->scrub_pages = xcphysinfo.scrub_pages;
+    physinfo->outstanding_pages = xcphysinfo.outstanding_pages;
     l = xc_sharing_freed_pages(ctx->xch);
     if (l == -ENOSYS) {
         l = 0;
@@ -4105,20 +4106,6 @@ libxl_numainfo *libxl_get_numainfo(libxl_ctx *ctx, int *nr)
     return ret;
 }
 
-uint64_t libxl_get_claiminfo(libxl_ctx *ctx)
-{
-    long l;
-
-    l = xc_domain_get_outstanding_pages(ctx->xch);
-    if (l < 0) {
-        LIBXL__LOG_ERRNOVAL(ctx, LIBXL__LOG_WARNING, l,
-                            "xc_domain_get_outstanding_pages failed.");
-        return ERROR_FAIL;
-    }
-    /* In pages */
-    return l;
-}
-
 const libxl_version_info* libxl_get_version_info(libxl_ctx *ctx)
 {
     union {
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index ef96bce1a7..0bc005e0ee 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -624,7 +624,6 @@ int libxl_wait_for_free_memory(libxl_ctx *ctx, uint32_t domid, uint32_t memory_k
 /* wait for the memory target of a domain to be reached */
 int libxl_wait_for_memory_target(libxl_ctx *ctx, uint32_t domid, int wait_secs);
 
-uint64_t libxl_get_claiminfo(libxl_ctx *ctx);
 int libxl_vncviewer_exec(libxl_ctx *ctx, uint32_t domid, int autopass);
 int libxl_console_exec(libxl_ctx *ctx, uint32_t domid, int cons_num, libxl_console_type type);
 /* libxl_primary_console_exec finds the domid and console number
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index ecf1f0bc4f..8262cba623 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -487,6 +487,7 @@ libxl_physinfo = Struct("physinfo", [
     ("total_pages", uint64),
     ("free_pages", uint64),
     ("scrub_pages", uint64),
+    ("outstanding_pages", uint64),
     ("sharing_freed_pages", uint64),
     ("sharing_used_frames", uint64),
 
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index c1a969b80c..edf0325fdd 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -4576,21 +4576,11 @@ static void output_physinfo(void)
     unsigned int i;
     libxl_bitmap cpumap;
     int n = 0;
-    long claims = 0;
 
     if (libxl_get_physinfo(ctx, &info) != 0) {
         fprintf(stderr, "libxl_physinfo failed.\n");
         return;
     }
-    /*
-     * Don't bother checking "claim_mode" as user might have turned it off
-     * and we have outstanding claims.
-     */
-    if ((claims = libxl_get_claiminfo(ctx)) < 0){
-        fprintf(stderr, "libxl_get_claiminfo failed. errno: %d (%s)\n",
-                errno, strerror(errno));
-        return;
-    }
     printf("nr_cpus                : %d\n", info.nr_cpus);
     printf("max_cpu_id             : %d\n", info.max_cpu_id);
     printf("nr_nodes               : %d\n", info.nr_nodes);
@@ -4610,15 +4600,15 @@ static void output_physinfo(void)
     if (vinfo) {
         i = (1 << 20) / vinfo->pagesize;
         printf("total_memory           : %"PRIu64"\n", info.total_pages / i);
-        printf("free_memory            : %"PRIu64"\n", (info.free_pages - claims) / i);
+        printf("free_memory            : %"PRIu64"\n", (info.free_pages - info.outstanding_pages) / i);
         printf("sharing_freed_memory   : %"PRIu64"\n", info.sharing_freed_pages / i);
         printf("sharing_used_memory    : %"PRIu64"\n", info.sharing_used_frames / i);
     }
     /*
      * Only if enabled (claim_mode=1) or there are outstanding claims.
      */
-    if (libxl_defbool_val(claim_mode) || claims)
-        printf("outstanding_claims     : %ld\n", claims / i);
+    if (libxl_defbool_val(claim_mode) || info.outstanding_pages)
+        printf("outstanding_claims     : %"PRIu64"\n", info.outstanding_pages / i);
 
     if (!libxl_get_freecpus(ctx, &cpumap)) {
         libxl_for_each_bit(i, cpumap)