[Xen-devel] [PATCH for-4.12 1/8] dom0/pvh: align allocation and mapping order to start address

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Due to the recent changes in the iommu mapping logic, the start
addresses provided need to be aligned to the order intended to be
mapped.

dom0 PVH domain builder didn't take this into account when populating
the p2m, fix this by making sure the order is chosen so that the start
address is aligned to it.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
Without this patch trying to create a PVH dom0 will trigger an assert
on certain hardware depending on the memory map.
---
 xen/arch/x86/hvm/dom0_build.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
index 51cf490811..a571d15c13 100644
--- a/xen/arch/x86/hvm/dom0_build.c
+++ b/xen/arch/x86/hvm/dom0_build.c
@@ -152,6 +152,8 @@ static int __init pvh_populate_memory_range(struct domain 
*d,
 
         order = get_order_from_pages(end - start + 1);
         order = min(order ? order - 1 : 0, max_order);
+        /* The order allocated and populated must be aligned to the address. */
+        order = min(order, start ? find_first_set_bit(start) : MAX_ORDER);
         page = alloc_domheap_pages(d, order, dom0_memflags | MEMF_no_scrub);
         if ( page == NULL )
         {
-- 
2.20.1


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