From: Will Deacon <will@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-arm-kernel@lists.infradead.org, Jan Kara <jack@suse.cz>,
Minchan Kim <minchan@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Vinayak Menon <vinmenon@codeaurora.org>,
kernel-team@android.com
Subject: Re: [PATCH 2/2] arm64: mm: Implement arch_wants_old_faultaround_pte()
Date: Wed, 9 Dec 2020 18:46:44 +0000 [thread overview]
Message-ID: <20201209184643.GB8778@willie-the-truck> (raw)
In-Reply-To: <20201209183509.GH13566@gaia>
On Wed, Dec 09, 2020 at 06:35:09PM +0000, Catalin Marinas wrote:
> On Wed, Dec 09, 2020 at 04:39:50PM +0000, Will Deacon wrote:
> > diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> > index da250e4741bd..3424f5881390 100644
> > --- a/arch/arm64/include/asm/cpufeature.h
> > +++ b/arch/arm64/include/asm/cpufeature.h
> > @@ -764,6 +764,18 @@ static inline bool cpu_has_hw_af(void)
> > ID_AA64MMFR1_HADBS_SHIFT);
> > }
> >
> > +static inline bool system_has_hw_af(void)
> > +{
> > + u64 mmfr1;
> > +
> > + if (!IS_ENABLED(CONFIG_ARM64_HW_AFDBM))
> > + return false;
> > +
> > + mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
> > + return cpuid_feature_extract_unsigned_field(mmfr1,
> > + ID_AA64MMFR1_HADBS_SHIFT);
> > +}
>
> Could we not add a new system-wide cpu feature that checks for hardware
> AF? This read_sanitised_ftr_reg() does a binary search on each
> invocation.
I posted a diff [1] which would allow removing the binary search for cases
where we can pass the register coding as a constant (like this), but
honestly, it's not like we have many ID registers so I doubt it really
matters in the grand scheme of things.
That said, I'm spinning a v2 anyway so I can include it for comments
since I haven't posted it as a proper patch before.
Will
[1] https://lore.kernel.org/r/20201202172727.GC29813@willie-the-truck
prev parent reply other threads:[~2020-12-09 18:46 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-09 16:39 [PATCH 0/2] Create 'old' ptes for faultaround mappings on arm64 with hardware access flag Will Deacon
2020-12-09 16:39 ` [PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting Will Deacon
2020-12-09 17:58 ` Linus Torvalds
2020-12-09 18:40 ` Will Deacon
2020-12-09 19:04 ` Linus Torvalds
2020-12-09 20:32 ` Matthew Wilcox
2020-12-09 21:04 ` Linus Torvalds
2020-12-10 15:08 ` Kirill A. Shutemov
2020-12-10 17:23 ` Linus Torvalds
[not found] ` <20201214160724.ewhjqoi32chheone@box>
2020-12-14 17:54 ` Linus Torvalds
2020-12-14 18:56 ` Matthew Wilcox
2020-12-16 17:07 ` Kirill A. Shutemov
2020-12-16 18:41 ` Linus Torvalds
2020-12-17 10:54 ` Kirill A. Shutemov
2020-12-17 18:22 ` Linus Torvalds
2020-12-18 11:04 ` Kirill A. Shutemov
2020-12-18 18:56 ` Linus Torvalds
2020-12-19 12:41 ` Kirill A. Shutemov
2020-12-19 20:08 ` Linus Torvalds
2020-12-19 20:34 ` Linus Torvalds
2020-12-22 10:00 ` Kirill A. Shutemov
2020-12-24 4:04 ` Hugh Dickins
2020-12-25 11:31 ` Kirill A. Shutemov
2020-12-26 17:57 ` Linus Torvalds
2020-12-26 20:43 ` Kirill A. Shutemov
2020-12-26 21:03 ` Hugh Dickins
2020-12-26 21:16 ` Linus Torvalds
2020-12-26 22:40 ` Kirill A. Shutemov
2020-12-27 0:45 ` Hugh Dickins
2020-12-27 2:38 ` Hugh Dickins
2020-12-27 19:38 ` Linus Torvalds
2020-12-27 20:32 ` Damian Tometzki
2020-12-27 22:35 ` Hugh Dickins
2020-12-27 23:12 ` Linus Torvalds
2020-12-27 23:40 ` Linus Torvalds
2020-12-27 23:55 ` Kirill A. Shutemov
2020-12-27 23:48 ` Kirill A. Shutemov
2020-12-28 1:54 ` Linus Torvalds
2020-12-28 6:43 ` Hugh Dickins
2020-12-28 12:53 ` Kirill A. Shutemov
2020-12-28 18:47 ` Linus Torvalds
2020-12-28 21:58 ` Linus Torvalds
2020-12-29 13:28 ` Kirill A. Shutemov
2020-12-29 15:19 ` Matthew Wilcox
2020-12-29 20:52 ` Linus Torvalds
2020-12-28 22:05 ` Kirill A. Shutemov
2020-12-28 22:12 ` Kirill A. Shutemov
2020-12-29 4:35 ` Hugh Dickins
2020-12-28 23:28 ` Linus Torvalds
2020-12-26 21:07 ` Linus Torvalds
2020-12-26 21:41 ` Matthew Wilcox
2020-12-09 16:39 ` [PATCH 2/2] arm64: mm: Implement arch_wants_old_faultaround_pte() Will Deacon
2020-12-09 18:35 ` Catalin Marinas
2020-12-09 18:46 ` Will Deacon [this message]
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=20201209184643.GB8778@willie-the-truck \
--to=will@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=catalin.marinas@arm.com \
--cc=jack@suse.cz \
--cc=kernel-team@android.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=minchan@kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=vinmenon@codeaurora.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).