[Xen-devel] [PATCH RFC v1 11/12] x86/mm: Prepare __ioremap_check_ram() for PG_reserved changes

[David Hildenbrand <david@xxxxxxxxxx>]

Right now, ZONE_DEVICE memory is always set PG_reserved. We want to
change that.

We could explicitly check for is_zone_device_page(page). But looking at
the pfn_valid() check, it seems safer to just use pfn_to_online_page()
here, that will skip all ZONE_DEVICE pages right away.

Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 arch/x86/mm/ioremap.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index a39dcdb5ae34..db6913b48edf 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -77,10 +77,17 @@ static unsigned int __ioremap_check_ram(struct resource 
*res)
        start_pfn = (res->start + PAGE_SIZE - 1) >> PAGE_SHIFT;
        stop_pfn = (res->end + 1) >> PAGE_SHIFT;
        if (stop_pfn > start_pfn) {
-               for (i = 0; i < (stop_pfn - start_pfn); ++i)
-                       if (pfn_valid(start_pfn + i) &&
-                           !PageReserved(pfn_to_page(start_pfn + i)))
+               for (i = 0; i < (stop_pfn - start_pfn); ++i) {
+                       struct page *page;
+                        /*
+                         * We treat any pages that are not online (not managed
+                         * by the buddy) as not being RAM. This includes
+                         * ZONE_DEVICE pages.
+                         */
+                       page = pfn_to_online_page(start_pfn + i);
+                       if (page && !PageReserved(page))
                                return IORES_MAP_SYSTEM_RAM;
+               }
        }
 
        return 0;
-- 
2.21.0


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