The patch titled
Subject: mm/memory_hotplug: add pgprot_t to mhp_params
has been added to the -mm tree. Its filename is
mm-memory_hotplug-add-pgprot_t-to-mhp_params.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory_hotplug-add-pgprot_t-to-mhp_params.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory_hotplug-add-pgprot_t-to-mhp_params.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
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
@@ -858,6 +858,18 @@ 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
@@ -868,7 +868,7 @@ 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
@@ -56,9 +56,12 @@ 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
@@ -312,6 +312,9 @@ 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
@@ -186,8 +186,8 @@ 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;
@@ -275,8 +275,8 @@ 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;
_
Patches currently in -mm which might be from logang@xxxxxxxxxxxx are
mm-memory_hotplug-drop-the-flags-field-from-struct-mhp_restrictions.patch
mm-memory_hotplug-rename-mhp_restrictions-to-mhp_params.patch
x86-mm-thread-pgprot_t-through-init_memory_mapping.patch
x86-mm-introduce-__set_memory_prot.patch
powerpc-mm-thread-pgprot_t-through-create_section_mapping.patch
mm-memory_hotplug-add-pgprot_t-to-mhp_params.patch
mm-memremap-set-caching-mode-for-pci-p2pdma-memory-to-wc.patch
