Hi, The main feedback from v1 was around the interface for arch_add_memory(). Per Dan's suggestions I've renamed the mhp_restrictions structure to mhp_modifiers and put a pgprot_t field in that structure. I've also included patch to drop the unused flags field. Thanks, Logan -- Changes in v2: * Rebased onto v5.5-rc5 * Renamed mhp_restrictions to mhp_modifiers and added the pgprot field to that structure instead of using an argument for arch_add_memory(). * Add patch to drop the unused flags field in mhp_restrictions A git branch is available here: https://github.com/sbates130272/linux-p2pmem remap_pages_cache_v2 -- Currently, the page tables created using memremap_pages() are always created with the PAGE_KERNEL cacheing mode. However, the P2PDMA code is creating pages for PCI BAR memory which should never be accessed through the cache and instead use either WC or UC. This still works in most cases, on x86, because the MTRR registers typically override the caching settings in the page tables for all of the IO memory to be UC-. However, this tends not to work so well on other arches or some rare x86 machines that have firmware which does not setup the MTRR registers in this way. Instead of this, this series proposes a change to arch_add_memory() to take the pgprot required by the mapping which allows us to explicitly set pagetable entries for P2PDMA memory to WC. This changes is pretty routine for most of the arches: x86_64, s390, arm64 and powerpc simply need to thread the pgprot through to where the page tables are setup. x86_32 unfortunately sets up the page tables at boot so must use _set_memory_prot() to change their caching mode. ia64 and sh don't appear to have an easy way to change the page tables so, for now at least, we just return -EINVAL on such mappings and thus they will not support P2PDMA memory until the work for this is done. -- Logan Gunthorpe (8): mm/memory_hotplug: Drop the flags field from struct mhp_restrictions mm/memory_hotplug: Rename mhp_restrictions to mhp_modifiers x86/mm: Thread pgprot_t through init_memory_mapping() x86/mm: Introduce _set_memory_prot() powerpc/mm: Thread pgprot_t through create_section_mapping() s390/mm: Thread pgprot_t through vmem_add_mapping() mm/memory_hotplug: Add pgprot_t to mhp_modifiers mm/memremap: Set caching mode for PCI P2PDMA memory to WC arch/arm64/mm/mmu.c | 7 ++-- arch/ia64/mm/init.c | 6 +++- arch/powerpc/include/asm/book3s/64/hash.h | 3 +- arch/powerpc/include/asm/book3s/64/radix.h | 3 +- arch/powerpc/include/asm/sparsemem.h | 3 +- arch/powerpc/mm/book3s64/hash_utils.c | 5 +-- arch/powerpc/mm/book3s64/pgtable.c | 7 ++-- arch/powerpc/mm/book3s64/radix_pgtable.c | 18 ++++++---- arch/powerpc/mm/mem.c | 10 +++--- arch/s390/include/asm/pgtable.h | 3 +- arch/s390/mm/extmem.c | 3 +- arch/s390/mm/init.c | 8 ++--- arch/s390/mm/vmem.c | 10 +++--- arch/sh/mm/init.c | 7 ++-- arch/x86/include/asm/page_types.h | 3 -- arch/x86/include/asm/pgtable.h | 3 ++ arch/x86/include/asm/set_memory.h | 1 + arch/x86/kernel/amd_gart_64.c | 3 +- arch/x86/mm/init.c | 9 ++--- arch/x86/mm/init_32.c | 12 +++++-- arch/x86/mm/init_64.c | 40 ++++++++++++---------- arch/x86/mm/mm_internal.h | 3 +- arch/x86/mm/pageattr.c | 7 ++++ arch/x86/platform/efi/efi_64.c | 3 +- include/linux/memory_hotplug.h | 16 ++++----- mm/memory_hotplug.c | 8 ++--- mm/memremap.c | 17 +++++---- 27 files changed, 132 insertions(+), 86 deletions(-) -- 2.20.1
