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 <logang@deltatee.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Dan 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.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 6d4e9c2..a374e4f 100644 (file)
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1382,7 +1382,8 @@ int arch_add_memory(int nid, u64 start, u64 size,
                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);
 

diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
index 97bbc23..d637b4e 100644 (file)
--- a/arch/ia64/mm/init.c
+++ b/arch/ia64/mm/init.c
@@ -676,6 +676,9 @@ int arch_add_memory(int nid, u64 start, u64 size,
        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",

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index bf63ab0..041ed7c 100644 (file)
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -132,7 +132,8 @@ int __ref arch_add_memory(int nid, u64 start, u64 size,
        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);

diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index e9e4a7a..87b2d02 100644 (file)
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -277,6 +277,9 @@ int arch_add_memory(int nid, u64 start, u64 size,
        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;

diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index e5114c0..b9de2d4 100644 (file)
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -412,6 +412,9 @@ int arch_add_memory(int nid, u64 start, u64 size,
        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))

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index ac75a83..4222a01 100644 (file)
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -824,6 +824,18 @@ int arch_add_memory(int nid, u64 start, u64 size,
 {
        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);
 }

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 7480de7..3b289c2 100644 (file)
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -867,7 +867,7 @@ int arch_add_memory(int nid, u64 start, u64 size,
        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);
 }

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 75f0f63..93d9ada 100644 (file)
--- 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;
 };
 
 /*

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index fbfe7b4..fc0aad0 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -311,6 +311,9 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
        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 memory_block *mem, void *arg)
  */
 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;

diff --git a/mm/memremap.c b/mm/memremap.c
index b0b5170..bc167cd 100644 (file)
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -189,8 +189,8 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
                 * 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 *pgmap, int nid)
        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, &params.pgprot, PHYS_PFN(res->start),
+                               0, resource_size(res));
        if (error)
                goto err_pfn_remap;