[v3,6/7] mm/memory_hotplug: Add pgprot_t to mhp_params
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Message ID 20200221182503.28317-7-logang@deltatee.com
State New
Headers show
Series
  • Allow setting caching mode in arch_add_memory() for P2PDMA
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Commit Message

Logan Gunthorpe Feb. 21, 2020, 6:25 p.m. UTC
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.

Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 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          | 5 +++++
 arch/x86/mm/init_64.c          | 2 +-
 include/linux/memory_hotplug.h | 2 ++
 mm/memory_hotplug.c            | 5 ++++-
 mm/memremap.c                  | 6 +++---
 10 files changed, 28 insertions(+), 7 deletions(-)

Comments

David Hildenbrand Feb. 24, 2020, 9:26 a.m. UTC | #1
On 21.02.20 19:25, Logan Gunthorpe wrote:
> 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.
> 
> Cc: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Acked-by: David Hildenbrand <david@redhat.com>
> Acked-by: Michal Hocko <mhocko@suse.com>

[...]

> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index c5df1b3dada0..30d6c1b8847e 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -56,9 +56,11 @@ enum {
>  /*
>   * Extended parameters for memory hotplug:
>   * altmap: alternative allocator for memmap array (optional)
> + * pgprot: page protection flags to apply to newly added page tables (required)

s/added/created/?
Dan Williams Feb. 29, 2020, 10:44 p.m. UTC | #2
On Fri, Feb 21, 2020 at 10:25 AM Logan Gunthorpe <logang@deltatee.com> wrote:
>
> 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.
>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Acked-by: David Hildenbrand <david@redhat.com>
> Acked-by: Michal Hocko <mhocko@suse.com>
> ---
>  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          | 5 +++++
>  arch/x86/mm/init_64.c          | 2 +-
>  include/linux/memory_hotplug.h | 2 ++
>  mm/memory_hotplug.c            | 5 ++++-
>  mm/memremap.c                  | 6 +++---
>  10 files changed, 28 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index ee37bca8aba8..ea3fa844a8a2 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1058,7 +1058,8 @@ 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 97bbc23ea1e3..d637b4ea3147 100644
> --- 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 19b1da5d7eca..832412bc7fad 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -138,7 +138,8 @@ 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 e9e4a7abd0cc..87b2d024e75a 100644
> --- 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 e5114c053364..b9de2d4fa57e 100644
> --- 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 e25a4218e6ff..96d8e4fb1cc8 100644
> --- a/arch/x86/mm/init_32.c
> +++ b/arch/x86/mm/init_32.c
> @@ -858,6 +858,11 @@ 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;
> +
> +       ret = _set_memory_prot(start, nr_pages, params->pgprot);

Perhaps a comment since it's not immediately obvious where the
PAGE_KERNEL prot was established, and perhaps add a conditional to
skip this call in the param->pgprot == PAGE_KERNEL case?

Other than that looks good to me, but only an ack since I'm only
testing the x86 changes.

Acked-by: Dan Williams <dan.j.williams@intel.com>
Logan Gunthorpe March 2, 2020, 6:55 p.m. UTC | #3
On 2020-02-29 3:44 p.m., Dan Williams wrote:
> On Fri, Feb 21, 2020 at 10:25 AM Logan Gunthorpe <logang@deltatee.com> wrote:
>>
>> 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.
>>
>> Cc: Dan Williams <dan.j.williams@intel.com>
>> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
>> Acked-by: David Hildenbrand <david@redhat.com>
>> Acked-by: Michal Hocko <mhocko@suse.com>
>> ---
>>  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          | 5 +++++
>>  arch/x86/mm/init_64.c          | 2 +-
>>  include/linux/memory_hotplug.h | 2 ++
>>  mm/memory_hotplug.c            | 5 ++++-
>>  mm/memremap.c                  | 6 +++---
>>  10 files changed, 28 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>> index ee37bca8aba8..ea3fa844a8a2 100644
>> --- a/arch/arm64/mm/mmu.c
>> +++ b/arch/arm64/mm/mmu.c
>> @@ -1058,7 +1058,8 @@ 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 97bbc23ea1e3..d637b4ea3147 100644
>> --- 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 19b1da5d7eca..832412bc7fad 100644
>> --- a/arch/powerpc/mm/mem.c
>> +++ b/arch/powerpc/mm/mem.c
>> @@ -138,7 +138,8 @@ 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 e9e4a7abd0cc..87b2d024e75a 100644
>> --- 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 e5114c053364..b9de2d4fa57e 100644
>> --- 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 e25a4218e6ff..96d8e4fb1cc8 100644
>> --- a/arch/x86/mm/init_32.c
>> +++ b/arch/x86/mm/init_32.c
>> @@ -858,6 +858,11 @@ 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;
>> +
>> +       ret = _set_memory_prot(start, nr_pages, params->pgprot);
> 
> Perhaps a comment since it's not immediately obvious where the
> PAGE_KERNEL prot was established, and perhaps add a conditional to
> skip this call in the param->pgprot == PAGE_KERNEL case?

Yes I can add the skip in the PAGE_KERNEL case. Though I'm not sure what
you are asking for with regards to the comment. Just that pgprot is set
by the caller usually to PAGE_KERNEL?

> Other than that looks good to me, but only an ack since I'm only
> testing the x86 changes.
> 
> Acked-by: Dan Williams <dan.j.williams@intel.com>


Thanks,

Logan
Dan Williams March 2, 2020, 8:26 p.m. UTC | #4
On Mon, Mar 2, 2020 at 10:55 AM Logan Gunthorpe <logang@deltatee.com> wrote:
>
>
>
> On 2020-02-29 3:44 p.m., Dan Williams wrote:
> > On Fri, Feb 21, 2020 at 10:25 AM Logan Gunthorpe <logang@deltatee.com> wrote:
> >>
> >> 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.
> >>
> >> Cc: Dan Williams <dan.j.williams@intel.com>
> >> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> >> Acked-by: David Hildenbrand <david@redhat.com>
> >> Acked-by: Michal Hocko <mhocko@suse.com>
> >> ---
> >>  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          | 5 +++++
> >>  arch/x86/mm/init_64.c          | 2 +-
> >>  include/linux/memory_hotplug.h | 2 ++
> >>  mm/memory_hotplug.c            | 5 ++++-
> >>  mm/memremap.c                  | 6 +++---
> >>  10 files changed, 28 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> >> index ee37bca8aba8..ea3fa844a8a2 100644
> >> --- a/arch/arm64/mm/mmu.c
> >> +++ b/arch/arm64/mm/mmu.c
> >> @@ -1058,7 +1058,8 @@ 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 97bbc23ea1e3..d637b4ea3147 100644
> >> --- 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 19b1da5d7eca..832412bc7fad 100644
> >> --- a/arch/powerpc/mm/mem.c
> >> +++ b/arch/powerpc/mm/mem.c
> >> @@ -138,7 +138,8 @@ 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 e9e4a7abd0cc..87b2d024e75a 100644
> >> --- 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 e5114c053364..b9de2d4fa57e 100644
> >> --- 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 e25a4218e6ff..96d8e4fb1cc8 100644
> >> --- a/arch/x86/mm/init_32.c
> >> +++ b/arch/x86/mm/init_32.c
> >> @@ -858,6 +858,11 @@ 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;
> >> +
> >> +       ret = _set_memory_prot(start, nr_pages, params->pgprot);
> >
> > Perhaps a comment since it's not immediately obvious where the
> > PAGE_KERNEL prot was established, and perhaps add a conditional to
> > skip this call in the param->pgprot == PAGE_KERNEL case?
>
> Yes I can add the skip in the PAGE_KERNEL case. Though I'm not sure what
> you are asking for with regards to the comment. Just that pgprot is set
> by the caller usually to PAGE_KERNEL?

No, I'm reacting to this comment in the changelog "For x86_32, set the
page tables explicitly using _set_memory_prot() (seeing they are
already mapped)". You've done some investigation that
x86_32::arch_add_memory() expects the page tables to be already
established. I think that's worth capturing inline in the code for
other people doing cross-arch arch_add_memory() changes.

Patch
diff mbox series

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index ee37bca8aba8..ea3fa844a8a2 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1058,7 +1058,8 @@  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 97bbc23ea1e3..d637b4ea3147 100644
--- 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 19b1da5d7eca..832412bc7fad 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -138,7 +138,8 @@  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 e9e4a7abd0cc..87b2d024e75a 100644
--- 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 e5114c053364..b9de2d4fa57e 100644
--- 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 e25a4218e6ff..96d8e4fb1cc8 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -858,6 +858,11 @@  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;
+
+	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 9e7692080dda..230240af38b4 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -868,7 +868,7 @@  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 c5df1b3dada0..30d6c1b8847e 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -56,9 +56,11 @@  enum {
 /*
  * Extended parameters for memory hotplug:
  * altmap: alternative allocator for memmap array (optional)
+ * pgprot: page protection flags to apply to newly added 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 c69469e1b40e..d7d4806ad81b 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -305,6 +305,9 @@  int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
 	unsigned long nr, start_sec, end_sec;
 	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;
@@ -993,7 +996,7 @@  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 6891a503a078..06742372a203 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -166,8 +166,8 @@  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;
 
@@ -255,8 +255,8 @@  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;