[Xen-devel] [PATCH] VT-d: fix off-by-one error in RMRR validation

["Jan Beulich" <JBeulich@xxxxxxxx>]

(base_addr,end_addr) is an inclusive range, and hence there shouldn't
be a subtraction of 1 in the second invocation of page_is_ram_type().
For RMRRs covering a single page that actually resulted in the
immediately preceding page to get checked (which could have resulted
in a false warning).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/drivers/passthrough/vtd/dmar.c
+++ b/xen/drivers/passthrough/vtd/dmar.c
@@ -520,7 +520,7 @@ acpi_parse_one_rmrr(struct acpi_dmar_ent
      * inform the user
      */
     if ( (!page_is_ram_type(paddr_to_pfn(base_addr), RAM_TYPE_RESERVED)) ||
-         (!page_is_ram_type(paddr_to_pfn(end_addr) - 1, RAM_TYPE_RESERVED)) )
+         (!page_is_ram_type(paddr_to_pfn(end_addr), RAM_TYPE_RESERVED)) )
     {
         dprintk(XENLOG_WARNING VTDPREFIX,
                 "  RMRR address range not in reserved memory "

vtd-rmrr-reserved-check.patch
Description: Text document

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