From: Mike Rapoport <rppt@kernel.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
Ard Biesheuvel <ardb@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
David Hildenbrand <david@redhat.com>,
Marc Zyngier <maz@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Mike Rapoport <rppt@linux.ibm.com>, Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [RFC/RFT PATCH 2/3] arm64: decouple check whether pfn is normal memory from pfn_valid()
Date: Thu, 8 Apr 2021 09:00:52 +0300 [thread overview]
Message-ID: <YG6cFKKimksg+FX3@kernel.org> (raw)
In-Reply-To: <4a788546-b854-fd35-644a-f1d9075a9a78@arm.com>
On Thu, Apr 08, 2021 at 10:44:58AM +0530, Anshuman Khandual wrote:
>
> On 4/7/21 10:56 PM, Mike Rapoport wrote:
> > From: Mike Rapoport <rppt@linux.ibm.com>
> >
> > The intended semantics of pfn_valid() is to verify whether there is a
> > struct page for the pfn in question and nothing else.
>
> Should there be a comment affirming this semantics interpretation, above the
> generic pfn_valid() in include/linux/mmzone.h ?
Yeah, that would have been helpful :)
> >
> > Yet, on arm64 it is used to distinguish memory areas that are mapped in the
> > linear map vs those that require ioremap() to access them.
> >
> > Introduce a dedicated pfn_is_memory() to perform such check and use it
> > where appropriate.
> >
> > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> > ---
> > arch/arm64/include/asm/memory.h | 2 +-
> > arch/arm64/include/asm/page.h | 1 +
> > arch/arm64/kvm/mmu.c | 2 +-
> > arch/arm64/mm/init.c | 6 ++++++
> > arch/arm64/mm/ioremap.c | 4 ++--
> > arch/arm64/mm/mmu.c | 2 +-
> > 6 files changed, 12 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> > index 0aabc3be9a75..7e77fdf71b9d 100644
> > --- a/arch/arm64/include/asm/memory.h
> > +++ b/arch/arm64/include/asm/memory.h
> > @@ -351,7 +351,7 @@ static inline void *phys_to_virt(phys_addr_t x)
> >
> > #define virt_addr_valid(addr) ({ \
> > __typeof__(addr) __addr = __tag_reset(addr); \
> > - __is_lm_address(__addr) && pfn_valid(virt_to_pfn(__addr)); \
> > + __is_lm_address(__addr) && pfn_is_memory(virt_to_pfn(__addr)); \
> > })
> >
> > void dump_mem_limit(void);
> > diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
> > index 012cffc574e8..32b485bcc6ff 100644
> > --- a/arch/arm64/include/asm/page.h
> > +++ b/arch/arm64/include/asm/page.h
> > @@ -38,6 +38,7 @@ void copy_highpage(struct page *to, struct page *from);
> > typedef struct page *pgtable_t;
> >
> > extern int pfn_valid(unsigned long);
> > +extern int pfn_is_memory(unsigned long);
> >
> > #include <asm/memory.h>
> >
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index 8711894db8c2..ad2ea65a3937 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -85,7 +85,7 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
> >
> > static bool kvm_is_device_pfn(unsigned long pfn)
> > {
> > - return !pfn_valid(pfn);
> > + return !pfn_is_memory(pfn);
> > }
> >
> > /*
> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> > index 3685e12aba9b..258b1905ed4a 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -258,6 +258,12 @@ int pfn_valid(unsigned long pfn)
> > }
> > EXPORT_SYMBOL(pfn_valid);
> >
> > +int pfn_is_memory(unsigned long pfn)
> > +{
> > + return memblock_is_map_memory(PFN_PHYS(pfn));
> > +}
> > +EXPORT_SYMBOL(pfn_is_memory);> +
>
> Should not this be generic though ? There is nothing platform or arm64
> specific in here.
As NOMAP itself is quite ARM specific, this check is currently only
relevant for arm64 and maybe arm32.
But probably having an EXPORT_SYMBOL wrapper for memblock_is_map_memory(),
say in memblock does make sense for all architectures that have
KEEP_MEMBLOCK.
> Wondering as pfn_is_memory() just indicates that the
> pfn is linear mapped, should not it be renamed as pfn_is_linear_memory()
> instead ? Regardless, it's fine either way.
Yeah, I agree that naming could be better here. I think that for a generic name
we'd need pfn_is_directly_mapped() so that it can be used on x86 ;-)
> > static phys_addr_t memory_limit = PHYS_ADDR_MAX;
> >
> > /*
> > diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c
> > index b5e83c46b23e..82a369b22ef5 100644
> > --- a/arch/arm64/mm/ioremap.c
> > +++ b/arch/arm64/mm/ioremap.c
> > @@ -43,7 +43,7 @@ static void __iomem *__ioremap_caller(phys_addr_t phys_addr, size_t size,
> > /*
> > * Don't allow RAM to be mapped.
> > */
> > - if (WARN_ON(pfn_valid(__phys_to_pfn(phys_addr))))
> > + if (WARN_ON(pfn_is_memory(__phys_to_pfn(phys_addr))))
> > return NULL;
> >
> > area = get_vm_area_caller(size, VM_IOREMAP, caller);
> > @@ -84,7 +84,7 @@ EXPORT_SYMBOL(iounmap);
> > void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size)
> > {
> > /* For normal memory we already have a cacheable mapping. */
> > - if (pfn_valid(__phys_to_pfn(phys_addr)))
> > + if (pfn_is_memory(__phys_to_pfn(phys_addr)))
> > return (void __iomem *)__phys_to_virt(phys_addr);
> >
> > return __ioremap_caller(phys_addr, size, __pgprot(PROT_NORMAL),
> > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> > index 5d9550fdb9cf..038d20fe163f 100644
> > --- a/arch/arm64/mm/mmu.c
> > +++ b/arch/arm64/mm/mmu.c
> > @@ -81,7 +81,7 @@ void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
> > pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
> > unsigned long size, pgprot_t vma_prot)
> > {
> > - if (!pfn_valid(pfn))
> > + if (!pfn_is_memory(pfn))
> > return pgprot_noncached(vma_prot);
> > else if (file->f_flags & O_SYNC)
> > return pgprot_writecombine(vma_prot);
> >
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2021-04-08 6:01 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 17:26 [RFC/RFT PATCH 0/3] arm64: drop pfn_valid_within() and simplify pfn_valid() Mike Rapoport
2021-04-07 17:26 ` [RFC/RFT PATCH 1/3] memblock: update initialization of reserved pages Mike Rapoport
2021-04-08 5:16 ` Anshuman Khandual
2021-04-08 5:48 ` Mike Rapoport
2021-04-14 15:12 ` David Hildenbrand
2021-04-14 15:27 ` Ard Biesheuvel
2021-04-14 15:52 ` David Hildenbrand
2021-04-14 20:24 ` Mike Rapoport
2021-04-15 9:30 ` David Hildenbrand
2021-04-16 11:44 ` Mike Rapoport
2021-04-16 11:54 ` David Hildenbrand
2021-04-14 20:11 ` Mike Rapoport
2021-04-14 20:06 ` Mike Rapoport
2021-04-07 17:26 ` [RFC/RFT PATCH 2/3] arm64: decouple check whether pfn is normal memory from pfn_valid() Mike Rapoport
2021-04-08 5:14 ` Anshuman Khandual
2021-04-08 6:00 ` Mike Rapoport [this message]
2021-04-14 15:58 ` David Hildenbrand
2021-04-14 20:29 ` Mike Rapoport
2021-04-15 9:31 ` David Hildenbrand
2021-04-16 11:40 ` Mike Rapoport
2021-04-07 17:26 ` [RFC/RFT PATCH 3/3] arm64: drop pfn_valid_within() and simplify pfn_valid() Mike Rapoport
2021-04-08 5:12 ` Anshuman Khandual
2021-04-08 6:17 ` Mike Rapoport
2021-04-08 5:19 ` [RFC/RFT PATCH 0/3] " Anshuman Khandual
2021-04-08 6:27 ` Mike Rapoport
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=YG6cFKKimksg+FX3@kernel.org \
--to=rppt@kernel.org \
--cc=anshuman.khandual@arm.com \
--cc=ardb@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=david@redhat.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mark.rutland@arm.com \
--cc=maz@kernel.org \
--cc=rppt@linux.ibm.com \
--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).