From: Will Deacon <will@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: maz@kernel.org, dbrazdil@google.com,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCHv2 3/3] arm64: cpufeature: upgrade hyp caps to final
Date: Fri, 30 Oct 2020 08:24:01 +0000 [thread overview]
Message-ID: <20201030082400.GB32163@willie-the-truck> (raw)
In-Reply-To: <20201026134931.28246-4-mark.rutland@arm.com>
On Mon, Oct 26, 2020 at 01:49:31PM +0000, Mark Rutland wrote:
> We finalize caps before initializing kvm hyp code, and any use of
> cpus_have_const_cap() in kvm hyp code generates redundant and
> potentially unsound code to read the cpu_hwcaps array.
>
> A number of helper functions used in both hyp context and regular kernel
> context use cpus_have_const_cap(), as some regular kernel code runs
> before the capabilities are finalized. It's tedious and error-prone to
> write separate copies of these for hyp and non-hyp code.
>
> So that we can avoid the redundant code, let's automatically upgrade
> cpus_have_const_cap() to cpus_have_final_cap() when used in hyp context.
> With this change, there's never a reason to access to cpu_hwcaps array
> from hyp code, and we don't need to create an NVHE alias for this.
>
> This should have no effect on non-hyp code.
>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: David Brazdil <dbrazdil@google.com>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Will Deacon <will@kernel.org>
> ---
> arch/arm64/include/asm/cpufeature.h | 26 ++++++++++++++++++++++++--
> arch/arm64/include/asm/virt.h | 12 ------------
> arch/arm64/kernel/image-vars.h | 1 -
> 3 files changed, 24 insertions(+), 15 deletions(-)
[...]
> diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
> index 61684a5009148..c615b285ff5b3 100644
> --- a/arch/arm64/kernel/image-vars.h
> +++ b/arch/arm64/kernel/image-vars.h
> @@ -87,7 +87,6 @@ KVM_NVHE_ALIAS(__icache_flags);
> /* Kernel symbols needed for cpus_have_final/const_caps checks. */
> KVM_NVHE_ALIAS(arm64_const_caps_ready);
> KVM_NVHE_ALIAS(cpu_hwcap_keys);
> -KVM_NVHE_ALIAS(cpu_hwcaps);
Nice!
Acked-by: Will Deacon <will@kernel.org>
Will
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-10-30 8:25 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 13:49 [PATCHv2 0/3] arm64: kvm: avoid referencing cpu_hwcaps from hyp Mark Rutland
2020-10-26 13:49 ` [PATCHv2 1/3] arm64: kvm: factor out is_{vhe,nvhe}_hyp_code() Mark Rutland
2020-10-30 8:21 ` Will Deacon
2020-10-26 13:49 ` [PATCHv2 2/3] arm64: cpufeature: reorder cpus_have_{const, final}_cap() Mark Rutland
2020-10-30 8:18 ` [PATCHv2 2/3] arm64: cpufeature: reorder cpus_have_{const,final}_cap() Will Deacon
2020-10-30 8:20 ` Will Deacon
2020-10-30 14:18 ` Mark Rutland
2020-10-26 13:49 ` [PATCHv2 3/3] arm64: cpufeature: upgrade hyp caps to final Mark Rutland
2020-10-30 8:24 ` Will Deacon [this message]
2020-10-29 19:48 ` [PATCHv2 0/3] arm64: kvm: avoid referencing cpu_hwcaps from hyp Marc Zyngier
2020-10-30 10:59 ` Marc Zyngier
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=20201030082400.GB32163@willie-the-truck \
--to=will@kernel.org \
--cc=dbrazdil@google.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=maz@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