From: Logan Gunthorpe <logang@xxxxxxxxxxxx> 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. Link: http://lkml.kernel.org/r/20200306170846.9333-7-logang@xxxxxxxxxxxx Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> Acked-by: David Hildenbrand <david@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Eric Badger <ebadger@xxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Jason Gunthorpe <jgg@xxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/arm64/mm/mmu.c | 3 ++- arch/ia64/mm/init.c | 3 +++ arch/powerpc/mm/mem.c | 3 ++- arch/s390/mm/init.c | 3 +++ arch/sh/mm/init.c | 3 +++ arch/x86/mm/init_32.c | 12 ++++++++++++ arch/x86/mm/init_64.c | 2 +- include/linux/memory_hotplug.h | 3 +++ mm/memory_hotplug.c | 5 ++++- mm/memremap.c | 6 +++--- 10 files changed, 36 insertions(+), 7 deletions(-) --- a/arch/arm64/mm/mmu.c~mm-memory_hotplug-add-pgprot_t-to-mhp_params +++ a/arch/arm64/mm/mmu.c @@ -1382,7 +1382,8 @@ int arch_add_memory(int nid, u64 start, flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start), - size, PAGE_KERNEL, __pgd_pgtable_alloc, flags); + size, params->pgprot, __pgd_pgtable_alloc, + flags); memblock_clear_nomap(start, size); --- a/arch/ia64/mm/init.c~mm-memory_hotplug-add-pgprot_t-to-mhp_params +++ a/arch/ia64/mm/init.c @@ -676,6 +676,9 @@ int arch_add_memory(int nid, u64 start, unsigned long nr_pages = size >> PAGE_SHIFT; int ret; + if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot)) + return -EINVAL; + ret = __add_pages(nid, start_pfn, nr_pages, params); if (ret) printk("%s: Problem encountered in __add_pages() as ret=%d\n", --- a/arch/powerpc/mm/mem.c~mm-memory_hotplug-add-pgprot_t-to-mhp_params +++ a/arch/powerpc/mm/mem.c @@ -132,7 +132,8 @@ int __ref arch_add_memory(int nid, u64 s resize_hpt_for_hotplug(memblock_phys_mem_size()); start = (unsigned long)__va(start); - rc = create_section_mapping(start, start + size, nid, PAGE_KERNEL); + rc = create_section_mapping(start, start + size, nid, + params->pgprot); if (rc) { pr_warn("Unable to create mapping for hot added memory 0x%llx..0x%llx: %d\n", start, start + size, rc); --- a/arch/s390/mm/init.c~mm-memory_hotplug-add-pgprot_t-to-mhp_params +++ a/arch/s390/mm/init.c @@ -277,6 +277,9 @@ int arch_add_memory(int nid, u64 start, if (WARN_ON_ONCE(params->altmap)) return -EINVAL; + if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot)) + return -EINVAL; + rc = vmem_add_mapping(start, size); if (rc) return rc; --- a/arch/sh/mm/init.c~mm-memory_hotplug-add-pgprot_t-to-mhp_params +++ a/arch/sh/mm/init.c @@ -412,6 +412,9 @@ int arch_add_memory(int nid, u64 start, unsigned long nr_pages = size >> PAGE_SHIFT; int ret; + if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot) + return -EINVAL; + /* We only have ZONE_NORMAL, so this is easy.. */ ret = __add_pages(nid, start_pfn, nr_pages, params); if (unlikely(ret)) --- a/arch/x86/mm/init_32.c~mm-memory_hotplug-add-pgprot_t-to-mhp_params +++ a/arch/x86/mm/init_32.c @@ -824,6 +824,18 @@ int arch_add_memory(int nid, u64 start, { unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long nr_pages = size >> PAGE_SHIFT; + int ret; + + /* + * The page tables were already mapped at boot so if the caller + * requests a different mapping type then we must change all the + * pages with __set_memory_prot(). + */ + if (params->pgprot.pgprot != PAGE_KERNEL.pgprot) { + ret = __set_memory_prot(start, nr_pages, params->pgprot); + if (ret) + return ret; + } return __add_pages(nid, start_pfn, nr_pages, params); } --- a/arch/x86/mm/init_64.c~mm-memory_hotplug-add-pgprot_t-to-mhp_params +++ a/arch/x86/mm/init_64.c @@ -867,7 +867,7 @@ int arch_add_memory(int nid, u64 start, unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long nr_pages = size >> PAGE_SHIFT; - init_memory_mapping(start, start + size, PAGE_KERNEL); + init_memory_mapping(start, start + size, params->pgprot); return add_pages(nid, start_pfn, nr_pages, params); } --- a/include/linux/memory_hotplug.h~mm-memory_hotplug-add-pgprot_t-to-mhp_params +++ a/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; }; /* --- a/mm/memory_hotplug.c~mm-memory_hotplug-add-pgprot_t-to-mhp_params +++ a/mm/memory_hotplug.c @@ -311,6 +311,9 @@ int __ref __add_pages(int nid, unsigned int err; struct vmem_altmap *altmap = params->altmap; + if (WARN_ON_ONCE(!params->pgprot.pgprot)) + return -EINVAL; + err = check_hotplug_memory_addressable(pfn, nr_pages); if (err) return err; @@ -1002,7 +1005,7 @@ static int online_memory_block(struct me */ int __ref add_memory_resource(int nid, struct resource *res) { - struct mhp_params params = {}; + struct mhp_params params = { .pgprot = PAGE_KERNEL }; u64 start, size; bool new_node = false; int ret; --- a/mm/memremap.c~mm-memory_hotplug-add-pgprot_t-to-mhp_params +++ a/mm/memremap.c @@ -189,8 +189,8 @@ void *memremap_pages(struct dev_pagemap * We do not want any optional features only our own memmap */ .altmap = pgmap_altmap(pgmap), + .pgprot = PAGE_KERNEL, }; - pgprot_t pgprot = PAGE_KERNEL; int error, is_ram; bool need_devmap_managed = true; @@ -282,8 +282,8 @@ void *memremap_pages(struct dev_pagemap if (nid < 0) nid = numa_mem_id(); - error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(res->start), 0, - resource_size(res)); + error = track_pfn_remap(NULL, ¶ms.pgprot, PHYS_PFN(res->start), + 0, resource_size(res)); if (error) goto err_pfn_remap; _
