• Logan Gunthorpe's avatar
    mm/memory_hotplug: add pgprot_t to mhp_params · bfeb022f
    Logan Gunthorpe authored
    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: default avatarLogan Gunthorpe <logang@deltatee.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
    Acked-by: default avatarMichal Hocko <mhocko@suse.com>
    Acked-by: default avatarDan Williams <dan.j.williams@intel.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: Eric Badger <ebadger@gigaio.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Jason Gunthorpe <jgg@ziepe.ca>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Will Deacon <will@kernel.org>
    Link: http://lkml.kernel.org/r/20200306170846.9333-7-logang@deltatee.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    bfeb022f
memremap.c 13.1 KB