[Xen-changelog] [xen stable-4.12] xen/arm: fix nr_pdxs calculation

[patchbot@xxxxxxx]

commit 5572ba9676793ddc3f74f673ea502018d92fc3e0
Author:     Stefano Stabellini <sstabellini@xxxxxxxxxx>
AuthorDate: Mon Jun 3 15:02:43 2019 -0700
Commit:     Stefano Stabellini <sstabellini@xxxxxxxxxx>
CommitDate: Tue Oct 29 11:07:57 2019 -0700

    xen/arm: fix nr_pdxs calculation
    
    pfn_to_pdx expects an address, not a size, as a parameter. Specifically,
    it expects the end address, then the masks calculations compensate for
    any holes between start and end. Thus, we should pass the end address to
    pfn_to_pdx.
    
    The initial pdx is stored in frametable_base_pdx, so we can subtract the
    result of pfn_to_pdx(start_address) from nr_pdxs; we know that we don't
    need to cover any memory in the range 0-start in the frametable.
    
    Remove the variable `nr_pages' because it is unused.
    
    Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
    Reviewed-by: Julien Grall <julien.grall@xxxxxxx>
    CC: JBeulich@xxxxxxxx
    (cherry picked from commit f51027be0688540aaab61513b06a8693a37e4c00)
---
 xen/arch/arm/mm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 80049572d9..5042207c62 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -878,8 +878,8 @@ void __init setup_xenheap_mappings(unsigned long base_mfn,
 /* Map a frame table to cover physical addresses ps through pe */
 void __init setup_frametable_mappings(paddr_t ps, paddr_t pe)
 {
-    unsigned long nr_pages = (pe - ps) >> PAGE_SHIFT;
-    unsigned long nr_pdxs = pfn_to_pdx(nr_pages);
+    unsigned long nr_pdxs = mfn_to_pdx(mfn_add(maddr_to_mfn(pe), -1)) -
+                            mfn_to_pdx(maddr_to_mfn(ps)) + 1;
     unsigned long frametable_size = nr_pdxs * sizeof(struct page_info);
     mfn_t base_mfn;
     const unsigned long mapping_size = frametable_size < MB(32) ? MB(2) : 
MB(32);
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.12

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