From: Dan Williams <dan.j.williams@intel.com>
To: Logan Gunthorpe <logang@deltatee.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 12:26:45 -0800 [thread overview]
Message-ID: <CAPcyv4g3c0rhW0eofG6FFMVNVPiw5fxP7LUpFJ2OYdLCAabZ1Q@mail.gmail.com> (raw)
In-Reply-To: <8b13f6aa-77b7-a47d-1a49-b8e2f800ac9d@deltatee.com>
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.
next prev parent reply other threads:[~2020-03-02 20:26 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
2020-03-02 20:26 ` Dan Williams [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAPcyv4g3c0rhW0eofG6FFMVNVPiw5fxP7LUpFJ2OYdLCAabZ1Q@mail.gmail.com \
--to=dan.j.williams@intel.com \
--cc=akpm@linux-foundation.org \
--cc=benh@kernel.crashing.org \
--cc=bp@alien8.de \
--cc=catalin.marinas@arm.com \
--cc=dave.hansen@linux.intel.com \
--cc=david@redhat.com \
--cc=ebadger@gigaio.com \
--cc=hch@lst.de \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-ia64@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-s390@vger.kernel.org \
--cc=linux-sh@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=logang@deltatee.com \
--cc=luto@kernel.org \
--cc=mhocko@kernel.org \
--cc=mhocko@suse.com \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=platform-driver-x86@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).