From: Logan Gunthorpe <logang@deltatee.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
linux-ia64@vger.kernel.org,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-s390 <linux-s390@vger.kernel.org>,
Linux-sh <linux-sh@vger.kernel.org>,
platform-driver-x86@vger.kernel.org,
Linux MM <linux-mm@kvack.org>, Michal Hocko <mhocko@kernel.org>,
David Hildenbrand <david@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@lst.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Eric Badger <ebadger@gigaio.com>, Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH v3 6/7] mm/memory_hotplug: Add pgprot_t to mhp_params
Date: Mon, 2 Mar 2020 11:55:18 -0700 [thread overview]
Message-ID: <8b13f6aa-77b7-a47d-1a49-b8e2f800ac9d@deltatee.com> (raw)
In-Reply-To: <CAPcyv4gR1+NaWzteqNKip=cYk89oEVW18HNao7Xv=JipzzDagw@mail.gmail.com>
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
next prev parent reply other threads:[~2020-03-02 18:55 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 18:24 [PATCH v3 0/7] Allow setting caching mode in arch_add_memory() for P2PDMA Logan Gunthorpe
2020-02-21 18:24 ` [PATCH v3 1/7] mm/memory_hotplug: Drop the flags field from struct mhp_restrictions Logan Gunthorpe
2020-02-28 21:31 ` Dan Williams
2020-03-03 9:50 ` Michal Hocko
2020-02-21 18:24 ` [PATCH v3 2/7] mm/memory_hotplug: Rename mhp_restrictions to mhp_params Logan Gunthorpe
2020-02-24 9:11 ` David Hildenbrand
2020-02-29 20:44 ` Dan Williams
2020-03-03 9:50 ` Michal Hocko
2020-02-21 18:24 ` [PATCH v3 3/7] x86/mm: Thread pgprot_t through init_memory_mapping() Logan Gunthorpe
2020-02-29 22:37 ` Dan Williams
2020-03-03 9:52 ` Michal Hocko
2020-02-21 18:25 ` [PATCH v3 4/7] x86/mm: Introduce _set_memory_prot() Logan Gunthorpe
2020-02-29 22:33 ` Dan Williams
2020-03-02 18:46 ` Logan Gunthorpe
2020-02-21 18:25 ` [PATCH v3 5/7] powerpc/mm: Thread pgprot_t through create_section_mapping() Logan Gunthorpe
2020-02-21 18:25 ` [PATCH v3 6/7] mm/memory_hotplug: Add pgprot_t to mhp_params Logan Gunthorpe
2020-02-24 9:26 ` David Hildenbrand
2020-02-29 22:44 ` Dan Williams
2020-03-02 18:55 ` Logan Gunthorpe [this message]
2020-03-02 20:26 ` Dan Williams
2020-02-21 18:25 ` [PATCH v3 7/7] mm/memremap: Set caching mode for PCI P2PDMA memory to WC Logan Gunthorpe
2020-02-29 22:47 ` Dan Williams
2020-03-02 21:20 ` Logan Gunthorpe
2020-02-27 17:17 ` [PATCH v3 0/7] Allow setting caching mode in arch_add_memory() for P2PDMA Jason Gunthorpe
2020-02-27 17:21 ` Logan Gunthorpe
2020-02-27 17:43 ` Jason Gunthorpe
2020-02-27 17:54 ` Logan Gunthorpe
2020-02-27 17:55 ` Dan Williams
2020-02-27 18:03 ` Jason Gunthorpe
2020-02-27 18:08 ` Dan Williams
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