[Xen-devel] [PATCH 2/5] x86/PoD: Avoid using variable length arrays in p2m_pod_zero_check()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Callers of p2m_pod_zero_check() pass a count of up to POD_SWEEP_STRIDE.
Move the definition of POD_SWEEP_STRIDE and give the arrays a fixed
bound.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
---
 xen/arch/x86/mm/p2m-pod.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c
index f1b221f..7978456 100644
--- a/xen/arch/x86/mm/p2m-pod.c
+++ b/xen/arch/x86/mm/p2m-pod.c
@@ -862,15 +862,19 @@ p2m_pod_zero_check_superpage(struct p2m_domain *p2m, 
gfn_t gfn)
     return ret;
 }
 
+#define POD_SWEEP_LIMIT 1024
+#define POD_SWEEP_STRIDE  16
+
 static void
 p2m_pod_zero_check(struct p2m_domain *p2m, const gfn_t *gfns, unsigned int 
count)
 {
-    mfn_t mfns[count];
-    p2m_type_t types[count];
-    unsigned long *map[count];
+    mfn_t mfns[POD_SWEEP_STRIDE];
+    p2m_type_t types[POD_SWEEP_STRIDE];
+    unsigned long *map[POD_SWEEP_STRIDE];
     struct domain *d = p2m->domain;
     unsigned int i, j, max_ref = 1;
 
+    BUG_ON(count > POD_SWEEP_STRIDE);
 
     /* Allow an extra refcount for one shadow pt mapping in shadowed domains */
     if ( paging_mode_shadow(d) )
@@ -1012,8 +1016,6 @@ p2m_pod_zero_check(struct p2m_domain *p2m, const gfn_t 
*gfns, unsigned int count
             unmap_domain_page(map[i]);
 }
 
-#define POD_SWEEP_LIMIT 1024
-#define POD_SWEEP_STRIDE  16
 static void
 p2m_pod_emergency_sweep(struct p2m_domain *p2m)
 {
-- 
2.1.4


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