From bfeb022f8fe4c5afdcfd7a3d868fac9765f9bcad Mon Sep 17 00:00:00 2001 From: Logan Gunthorpe Date: Fri, 10 Apr 2020 14:33:36 -0700 Subject: mm/memory_hotplug: add pgprot_t to mhp_params devm_memremap_pages() is currently used by the PCI P2PDMA code to create struct page mappings for IO memory. At present, these mappings are created with PAGE_KERNEL which implies setting the PAT bits to be WB. However, on x86, an mtrr register will typically override this and force the cache type to be UC-. In the case firmware doesn't set this register it is effectively WB and will typically result in a machine check exception when it's accessed. Other arches are not currently likely to function correctly seeing they don't have any MTRR registers to fall back on. To solve this, provide a way to specify the pgprot value explicitly to arch_add_memory(). Of the arches that support MEMORY_HOTPLUG: x86_64, and arm64 need a simple change to pass the pgprot_t down to their respective functions which set up the page tables. For x86_32, set the page tables explicitly using _set_memory_prot() (seeing they are already mapped). For ia64, s390 and sh, reject anything but PAGE_KERNEL settings -- this should be fine, for now, seeing these architectures don't support ZONE_DEVICE. A check in __add_pages() is also added to ensure the pgprot parameter was set for all arches. Signed-off-by: Logan Gunthorpe Signed-off-by: Andrew Morton Acked-by: David Hildenbrand Acked-by: Michal Hocko Acked-by: Dan Williams Cc: Andy Lutomirski Cc: Benjamin Herrenschmidt Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christoph Hellwig Cc: Dave Hansen Cc: Eric Badger Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jason Gunthorpe Cc: Michael Ellerman Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Link: http://lkml.kernel.org/r/20200306170846.9333-7-logang@deltatee.com Signed-off-by: Linus Torvalds --- include/linux/memory_hotplug.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include') diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 75f0f6304735..93d9ada74ddd 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -60,9 +60,12 @@ enum { /* * Extended parameters for memory hotplug: * altmap: alternative allocator for memmap array (optional) + * pgprot: page protection flags to apply to newly created page tables + * (required) */ struct mhp_params { struct vmem_altmap *altmap; + pgprot_t pgprot; }; /* -- cgit v1.2.3-58-ga151