From: Marc Zyngier <maz@kernel.org>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Stefan Wahren <stefan.wahren@i2se.com>,
Corey Minyard <cminyard@mvista.com>,
minyard@acm.org, Catalin Marinas <catalin.marinas@arm.com>,
Andre Przywara <andre.przywara@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] arm64: Fix compile error with KVM and !HARDEN_BRANCH_PREDICTOR
Date: Tue, 03 Dec 2019 18:45:46 +0000 [thread overview]
Message-ID: <8274815953233fb2d522f216b36d7247@www.loen.fr> (raw)
In-Reply-To: <CAKv+Gu9mS2BZj+YMemMTy-e=42wBdu7u3+Rp=w9cWZXMmbpt7A@mail.gmail.com>
On 2019-12-03 18:35, Ard Biesheuvel wrote:
[...]
> OK, I have prepared a branch that carries all these patches in the
> right order with the upstream commit reference added to the commit
> log. I'll send this out for review first, before actually sending it
> to -stable, unless anyone feels that this is a bad idea.
>
> arm64: KVM: Move BP hardening vectors into .hyp.text section
> arm64: insn: Add N immediate encoding
> arm64: insn: Add encoder for bitwise operations using literals
> arm64: KVM: Dynamically patch the kernel/hyp VA mask
> arm64: cpufeatures: Drop the ARM64_HYP_OFFSET_LOW feature flag
> arm64; insn: Add encoder for the EXTR instruction
> arm64: insn: Allow ADD/SUB (immediate) with LSL #12
> arm64: KVM: Dynamically compute the HYP VA mask
> arm64: KVM: Introduce EL2 VA randomisation
> arm64: KVM: Move stashing of x0/x1 into the vector code itself
> arm64: KVM: Reserve 4 additional instructions in the BPI template
> arm64: KVM: Allow far branches from vector slots to the main vectors
> arm64: Make BP hardening slot counter available
> arm64: Move the content of bpi.S to hyp-entry.S
My personal take on this is that it is *a lot* of code that affects
a very critical path, and I'm not completely sure that it is what
we want for something as dated as 4.14.
The only valuable reason I can think of (aside of the vulnerability
mitigation aspect) would be if we need to backport more code to
the exception entry path for EL2. I don't know if there is such
need yet.
M.
--
Jazz is not dead. It just smells funny...
_______________________________________________
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:[~2019-12-03 18:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 18:10 [PATCH] arm64: Fix compile error with KVM and !HARDEN_BRANCH_PREDICTOR minyard
2019-11-28 17:20 ` Ard Biesheuvel
2019-11-29 7:21 ` Marc Zyngier
2019-11-29 7:25 ` Ard Biesheuvel
2019-11-29 9:04 ` Marc Zyngier
2019-12-03 18:35 ` Ard Biesheuvel
2019-12-03 18:45 ` Marc Zyngier [this message]
2019-12-03 19:16 ` Corey Minyard
2019-12-04 15:51 ` Ard Biesheuvel
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=8274815953233fb2d522f216b36d7247@www.loen.fr \
--to=maz@kernel.org \
--cc=andre.przywara@arm.com \
--cc=ard.biesheuvel@linaro.org \
--cc=catalin.marinas@arm.com \
--cc=cminyard@mvista.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=minyard@acm.org \
--cc=stefan.wahren@i2se.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).