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>

1 files changed, 5 insertions, 2 deletions

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 203f77a485..2162ef14d4 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -380,9 +380,12 @@ out:
     return ret;
 }
 
-long get_outstanding_claims(void)
+void get_outstanding_claims(uint64_t *free_pages, uint64_t *outstanding_pages)
 {
-    return outstanding_claims;
+    spin_lock(&heap_lock);
+    *outstanding_pages = outstanding_claims;
+    *free_pages =  avail_domheap_pages();
+    spin_unlock(&heap_lock);
 }
 
 static unsigned long init_node_heap(int node, unsigned long mfn,