[Xen-devel] [RFC XEN PATCH v4 01/41] x86_64/mm: fix the PDX group check in mem_hotadd_check()

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

The current check refuses the hot-plugged memory that falls in one
unused PDX group, which should be allowed.

Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/x86_64/mm.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 9b37da6698..839038b6c3 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -1295,12 +1295,8 @@ static int mem_hotadd_check(unsigned long spfn, unsigned 
long epfn)
         return 0;
 
     /* Make sure the new range is not present now */
-    sidx = ((pfn_to_pdx(spfn) + PDX_GROUP_COUNT - 1)  & ~(PDX_GROUP_COUNT - 1))
-            / PDX_GROUP_COUNT;
+    sidx = (pfn_to_pdx(spfn) & ~(PDX_GROUP_COUNT - 1)) / PDX_GROUP_COUNT;
     eidx = (pfn_to_pdx(epfn - 1) & ~(PDX_GROUP_COUNT - 1)) / PDX_GROUP_COUNT;
-    if (sidx >= eidx)
-        return 0;
-
     s = find_next_zero_bit(pdx_group_valid, eidx, sidx);
     if ( s > eidx )
         return 0;
-- 
2.15.1


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