From: Marc Zyngier <maz@kernel.org>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Oliver Upton <oliver.upton@linux.dev>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Arnd Bergmann <arnd@arndb.de>, Oleg Nesterov <oleg@redhat.com>,
Eric Biederman <ebiederm@xmission.com>,
Shuah Khan <shuah@kernel.org>,
"Rick P. Edgecombe" <rick.p.edgecombe@intel.com>,
Deepak Gupta <debug@rivosinc.com>,
Ard Biesheuvel <ardb@kernel.org>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
Kees Cook <kees@kernel.org>, "H.J. Lu" <hjl.tools@gmail.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Florian Weimer <fweimer@redhat.com>,
Christian Brauner <brauner@kernel.org>,
Thiago Jung Bauermann <thiago.bauermann@linaro.org>,
Ross Burton <ross.burton@arm.com>,
David Spickett <david.spickett@arm.com>,
Yury Khrustalev <yury.khrustalev@arm.com>,
Wilco Dijkstra <wilco.dijkstra@arm.com>,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org
Subject: Re: [PATCH v13 16/40] KVM: arm64: Manage GCS access and registers for guests
Date: Wed, 02 Oct 2024 20:29:28 +0100 [thread overview]
Message-ID: <868qv6717r.wl-maz@kernel.org> (raw)
In-Reply-To: <37fbc082-6bda-46e3-9ee7-9240b41f26fd@sirena.org.uk>
On Wed, 02 Oct 2024 19:24:12 +0100,
Mark Brown <broonie@kernel.org> wrote:
>
> [1 <text/plain; us-ascii (7bit)>]
> On Wed, Oct 02, 2024 at 04:55:25PM +0100, Marc Zyngier wrote:
> > Marc Zyngier <maz@kernel.org> wrote:
>
> > > > + if (!kvm_has_gcs(kvm))
> > > > + kvm->arch.fgu[HFGxTR_GROUP] |= (HFGxTR_EL2_nGCS_EL0 |
> > > > + HFGxTR_EL2_nGCS_EL1);
>
> > > Why are you still allowing the GCS instructions when GCS isn't
> > > enabled?
>
> > Scratch that, they are NOPs when GCS isn't enabled, so there shouldn't
> > be any need for extra traps.
>
> They are, though really they should UNDEF if GCS isn't there (which I
> had thought was what you were referencing here). Equally we only have
> traps for a subset of GCS instructions and it's not like there aren't a
> whole bunch of untrappable extensions anyway so it's not clear it's
> worth the effort just for that.
If the encodings UNDEF when GCS is not implemented (i.e. they are not
in the NOP space), then all trapable instructions should absolutely
UNDEF (and yes, it is worth the effort, even if it is only to
demonstrate that the architecture is sub-par).
So I expect the next version to handle traps for GCSPUSHX, GCSPOPX,
GCSPUSHM, GCSSTR and GCSSTTR when GCS isn't enabled.
I'm also pretty sure this is missing some form of sanitisation for
PSTATE.EXLOCK, and looking at the pseudocode, you seem to be missing
the handling of that bit on exception injection.
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2024-10-02 19:29 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-01 22:58 [PATCH v13 00/40] arm64/gcs: Provide support for GCS in userspace Mark Brown
2024-10-01 22:58 ` [PATCH v13 01/40] mm: Introduce ARCH_HAS_USER_SHADOW_STACK Mark Brown
2024-10-01 22:58 ` [PATCH v13 02/40] mm: Define VM_HIGH_ARCH_6 Mark Brown
2024-10-01 22:58 ` [PATCH v13 03/40] arm64/mm: Restructure arch_validate_flags() for extensibility Mark Brown
2024-10-01 22:58 ` [PATCH v13 04/40] prctl: arch-agnostic prctl for shadow stack Mark Brown
2024-10-01 23:13 ` Deepak Gupta
2024-10-01 22:58 ` [PATCH v13 05/40] mman: Add map_shadow_stack() flags Mark Brown
2024-10-01 22:58 ` [PATCH v13 06/40] arm64: Document boot requirements for Guarded Control Stacks Mark Brown
2024-10-01 22:58 ` [PATCH v13 07/40] arm64/gcs: Document the ABI " Mark Brown
2024-10-01 22:58 ` [PATCH v13 08/40] arm64/sysreg: Add definitions for architected GCS caps Mark Brown
2024-10-01 22:58 ` [PATCH v13 09/40] arm64/gcs: Add manual encodings of GCS instructions Mark Brown
2024-10-01 22:58 ` [PATCH v13 10/40] arm64/gcs: Provide put_user_gcs() Mark Brown
2024-10-01 22:58 ` [PATCH v13 11/40] arm64/gcs: Provide basic EL2 setup to allow GCS usage at EL0 and EL1 Mark Brown
2024-10-09 20:49 ` Nathan Chancellor
2024-10-10 15:18 ` Marc Zyngier
2024-10-10 17:16 ` Catalin Marinas
2024-10-11 12:55 ` Marc Zyngier
2024-10-14 16:31 ` Catalin Marinas
2024-10-15 13:05 ` Catalin Marinas
2024-10-01 22:58 ` [PATCH v13 12/40] arm64/cpufeature: Runtime detection of Guarded Control Stack (GCS) Mark Brown
2024-10-01 22:58 ` [PATCH v13 13/40] arm64/mm: Allocate PIE slots for EL0 guarded control stack Mark Brown
2024-10-01 22:58 ` [PATCH v13 14/40] mm: Define VM_SHADOW_STACK for arm64 when we support GCS Mark Brown
2024-10-01 22:58 ` [PATCH v13 15/40] arm64/mm: Map pages for guarded control stack Mark Brown
2024-10-01 22:58 ` [PATCH v13 16/40] KVM: arm64: Manage GCS access and registers for guests Mark Brown
2024-10-02 0:24 ` Marc Zyngier
2024-10-02 15:55 ` Marc Zyngier
2024-10-02 18:24 ` Mark Brown
2024-10-02 19:29 ` Marc Zyngier [this message]
2024-10-03 14:50 ` Mark Brown
2024-10-01 22:58 ` [PATCH v13 17/40] arm64/idreg: Add overrride for GCS Mark Brown
2024-10-01 22:58 ` [PATCH v13 18/40] arm64/hwcap: Add hwcap " Mark Brown
2024-10-03 16:25 ` Yury Khrustalev
2024-10-01 22:58 ` [PATCH v13 19/40] arm64/traps: Handle GCS exceptions Mark Brown
2024-10-01 22:58 ` [PATCH v13 20/40] arm64/mm: Handle GCS data aborts Mark Brown
2024-10-01 22:59 ` [PATCH v13 21/40] arm64/gcs: Context switch GCS state for EL0 Mark Brown
2024-10-01 22:59 ` [PATCH v13 22/40] arm64/gcs: Ensure that new threads have a GCS Mark Brown
2024-10-04 11:18 ` Catalin Marinas
2024-10-04 11:50 ` Mark Brown
2024-10-01 22:59 ` [PATCH v13 23/40] arm64/gcs: Implement shadow stack prctl() interface Mark Brown
2024-10-01 22:59 ` [PATCH v13 24/40] arm64/mm: Implement map_shadow_stack() Mark Brown
2024-10-01 22:59 ` [PATCH v13 25/40] arm64/signal: Set up and restore the GCS context for signal handlers Mark Brown
2024-10-01 22:59 ` [PATCH v13 26/40] arm64/signal: Expose GCS state in signal frames Mark Brown
2024-10-01 22:59 ` [PATCH v13 27/40] arm64/ptrace: Expose GCS via ptrace and core files Mark Brown
2024-10-01 22:59 ` [PATCH v13 28/40] arm64: Add Kconfig for Guarded Control Stack (GCS) Mark Brown
2024-10-01 22:59 ` [PATCH v13 29/40] kselftest/arm64: Verify the GCS hwcap Mark Brown
2024-10-01 22:59 ` [PATCH v13 30/40] kselftest/arm64: Add GCS as a detected feature in the signal tests Mark Brown
2024-10-01 22:59 ` [PATCH v13 31/40] kselftest/arm64: Add framework support for GCS to signal handling tests Mark Brown
2024-10-01 22:59 ` [PATCH v13 32/40] kselftest/arm64: Allow signals tests to specify an expected si_code Mark Brown
2024-10-01 22:59 ` [PATCH v13 33/40] kselftest/arm64: Always run signals tests with GCS enabled Mark Brown
2024-10-01 22:59 ` [PATCH v13 34/40] kselftest/arm64: Add very basic GCS test program Mark Brown
2024-10-01 22:59 ` [PATCH v13 35/40] kselftest/arm64: Add a GCS test program built with the system libc Mark Brown
2024-10-01 22:59 ` [PATCH v13 36/40] kselftest/arm64: Add test coverage for GCS mode locking Mark Brown
2024-10-01 22:59 ` [PATCH v13 37/40] kselftest/arm64: Add GCS signal tests Mark Brown
2024-10-01 22:59 ` [PATCH v13 38/40] kselftest/arm64: Add a GCS stress test Mark Brown
2024-10-01 22:59 ` [PATCH v13 39/40] kselftest/arm64: Enable GCS for the FP stress tests Mark Brown
2024-10-01 22:59 ` [PATCH v13 40/40] KVM: selftests: arm64: Add GCS registers to get-reg-list Mark Brown
2024-10-04 13:52 ` (subset) [PATCH v13 00/40] arm64/gcs: Provide support for GCS in userspace Catalin Marinas
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=868qv6717r.wl-maz@kernel.org \
--to=maz@kernel.org \
--cc=Szabolcs.Nagy@arm.com \
--cc=akpm@linux-foundation.org \
--cc=aou@eecs.berkeley.edu \
--cc=ardb@kernel.org \
--cc=arnd@arndb.de \
--cc=brauner@kernel.org \
--cc=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=corbet@lwn.net \
--cc=david.spickett@arm.com \
--cc=debug@rivosinc.com \
--cc=ebiederm@xmission.com \
--cc=fweimer@redhat.com \
--cc=hjl.tools@gmail.com \
--cc=james.morse@arm.com \
--cc=kees@kernel.org \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-riscv@lists.infradead.org \
--cc=oleg@redhat.com \
--cc=oliver.upton@linux.dev \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=rick.p.edgecombe@intel.com \
--cc=ross.burton@arm.com \
--cc=shuah@kernel.org \
--cc=suzuki.poulose@arm.com \
--cc=thiago.bauermann@linaro.org \
--cc=wilco.dijkstra@arm.com \
--cc=will@kernel.org \
--cc=yury.khrustalev@arm.com \
/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).