From: Will Deacon <will.deacon@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Christoffer Dall <cdall@linaro.org>,
linux-arm-kernel@lists.infradead.org, arnd@arndb.de,
catalin.marinas@arm.com, christoffer.dall@linaro.org,
Dave.Martin@arm.com, jiong.wang@arm.com,
kvmarm@lists.cs.columbia.edu, linux-arch@vger.kernel.org,
marc.zyngier@arm.com, suzuki.poulose@arm.com, yao.qi@arm.com,
linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com
Subject: Re: [PATCH 10/11] arm64/kvm: context-switch ptrauth registers
Date: Tue, 1 Aug 2017 15:32:27 +0100 [thread overview]
Message-ID: <20170801143227.GC11534@arm.com> (raw)
In-Reply-To: <20170801142603.GE9347@leverpostej>
On Tue, Aug 01, 2017 at 03:26:07PM +0100, Mark Rutland wrote:
> On Tue, Aug 01, 2017 at 01:00:14PM +0200, Christoffer Dall wrote:
> > On Wed, Jul 19, 2017 at 05:01:31PM +0100, Mark Rutland wrote:
> > > When pointer authentication is supported, a guest may wish to use it.
> > > This patch adds the necessary KVM infrastructure for this to work, with
> > > a semi-lazy context switch of the pointer auth state.
> > >
> > > When we schedule a vcpu, we disable guest usage of pointer
> > > authentication instructions and accesses to the keys. While these are
> > > disabled, we avoid context-switching the keys. When we trap the guest
> > > trying to use pointer authentication functionality, we change to eagerly
> > > context-switching the keys, and enable the feature. The next time the
> > > vcpu is scheduled out/in, we start again.
> > >
> > > This is sufficient for systems with uniform pointer authentication
> > > support. For systems with mismatched support, it will be necessary to
> >
> > What is mismatched support? You mean systems where one CPU has ptrauth
> > and another one doesn't (or if they both have it but in different ways)?
>
> Both! Any case where the support is not uniform across all CPUs.
>
> A CPU can implement address auth and/or generic auth, and either may use
> an architected algorithm or an IMP DEF algorithm.
>
> Even if all CPUs report an IMP DEF algorithm, the particular algorithm
> may differ across CPUs.
I know you don't like it, but I think we should resort to MIDR at that point
because otherwise IMP DEF algorithms will never be used by Linux and people
will complain.
Will
WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 10/11] arm64/kvm: context-switch ptrauth registers
Date: Tue, 1 Aug 2017 15:32:27 +0100 [thread overview]
Message-ID: <20170801143227.GC11534@arm.com> (raw)
In-Reply-To: <20170801142603.GE9347@leverpostej>
On Tue, Aug 01, 2017 at 03:26:07PM +0100, Mark Rutland wrote:
> On Tue, Aug 01, 2017 at 01:00:14PM +0200, Christoffer Dall wrote:
> > On Wed, Jul 19, 2017 at 05:01:31PM +0100, Mark Rutland wrote:
> > > When pointer authentication is supported, a guest may wish to use it.
> > > This patch adds the necessary KVM infrastructure for this to work, with
> > > a semi-lazy context switch of the pointer auth state.
> > >
> > > When we schedule a vcpu, we disable guest usage of pointer
> > > authentication instructions and accesses to the keys. While these are
> > > disabled, we avoid context-switching the keys. When we trap the guest
> > > trying to use pointer authentication functionality, we change to eagerly
> > > context-switching the keys, and enable the feature. The next time the
> > > vcpu is scheduled out/in, we start again.
> > >
> > > This is sufficient for systems with uniform pointer authentication
> > > support. For systems with mismatched support, it will be necessary to
> >
> > What is mismatched support? You mean systems where one CPU has ptrauth
> > and another one doesn't (or if they both have it but in different ways)?
>
> Both! Any case where the support is not uniform across all CPUs.
>
> A CPU can implement address auth and/or generic auth, and either may use
> an architected algorithm or an IMP DEF algorithm.
>
> Even if all CPUs report an IMP DEF algorithm, the particular algorithm
> may differ across CPUs.
I know you don't like it, but I think we should resort to MIDR at that point
because otherwise IMP DEF algorithms will never be used by Linux and people
will complain.
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Christoffer Dall <cdall@linaro.org>,
linux-arm-kernel@lists.infradead.org, arnd@arndb.de,
catalin.marinas@arm.com, christoffer.dall@linaro.org,
Dave.Martin@arm.com, jiong.wang@arm.com,
kvmarm@lists.cs.columbia.edu, linux-arch@vger.kernel.org,
marc.zyngier@arm.com, suzuki.poulose@arm.com, yao.qi@arm.com,
linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com
Subject: [kernel-hardening] Re: [PATCH 10/11] arm64/kvm: context-switch ptrauth registers
Date: Tue, 1 Aug 2017 15:32:27 +0100 [thread overview]
Message-ID: <20170801143227.GC11534@arm.com> (raw)
In-Reply-To: <20170801142603.GE9347@leverpostej>
On Tue, Aug 01, 2017 at 03:26:07PM +0100, Mark Rutland wrote:
> On Tue, Aug 01, 2017 at 01:00:14PM +0200, Christoffer Dall wrote:
> > On Wed, Jul 19, 2017 at 05:01:31PM +0100, Mark Rutland wrote:
> > > When pointer authentication is supported, a guest may wish to use it.
> > > This patch adds the necessary KVM infrastructure for this to work, with
> > > a semi-lazy context switch of the pointer auth state.
> > >
> > > When we schedule a vcpu, we disable guest usage of pointer
> > > authentication instructions and accesses to the keys. While these are
> > > disabled, we avoid context-switching the keys. When we trap the guest
> > > trying to use pointer authentication functionality, we change to eagerly
> > > context-switching the keys, and enable the feature. The next time the
> > > vcpu is scheduled out/in, we start again.
> > >
> > > This is sufficient for systems with uniform pointer authentication
> > > support. For systems with mismatched support, it will be necessary to
> >
> > What is mismatched support? You mean systems where one CPU has ptrauth
> > and another one doesn't (or if they both have it but in different ways)?
>
> Both! Any case where the support is not uniform across all CPUs.
>
> A CPU can implement address auth and/or generic auth, and either may use
> an architected algorithm or an IMP DEF algorithm.
>
> Even if all CPUs report an IMP DEF algorithm, the particular algorithm
> may differ across CPUs.
I know you don't like it, but I think we should resort to MIDR at that point
because otherwise IMP DEF algorithms will never be used by Linux and people
will complain.
Will
next prev parent reply other threads:[~2017-08-01 14:32 UTC|newest]
Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-19 16:01 [PATCH 00/11] ARMv8.3 pointer authentication userspace support Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` [PATCH 01/11] arm64: docs: describe ELF hwcaps Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-21 17:05 ` Dave Martin
2017-07-21 17:05 ` [kernel-hardening] " Dave Martin
2017-07-21 17:05 ` Dave Martin
2017-07-21 17:05 ` Dave Martin
2017-07-24 10:47 ` Suzuki K Poulose
2017-07-24 10:47 ` [kernel-hardening] " Suzuki K Poulose
2017-07-24 10:47 ` Suzuki K Poulose
2017-08-03 14:49 ` Catalin Marinas
2017-08-03 14:49 ` [kernel-hardening] " Catalin Marinas
2017-08-03 14:49 ` Catalin Marinas
2017-08-03 17:57 ` Kees Cook
2017-08-03 17:57 ` [kernel-hardening] " Kees Cook
2017-08-03 17:57 ` Kees Cook
2017-08-03 17:57 ` Kees Cook
2017-07-19 16:01 ` [PATCH 02/11] asm-generic: mm_hooks: allow hooks to be overridden individually Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` [PATCH 03/11] arm64: add pointer authentication register bits Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` [PATCH 04/11] arm64/cpufeature: add ARMv8.3 id_aa64isar1 bits Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-24 10:54 ` Suzuki K Poulose
2017-07-24 10:54 ` [kernel-hardening] " Suzuki K Poulose
2017-07-24 10:54 ` Suzuki K Poulose
2017-07-19 16:01 ` [PATCH 05/11] arm64/cpufeature: detect pointer authentication Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` [PATCH 06/11] arm64: Don't trap host pointer auth use to EL2 Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-24 10:37 ` Dave Martin
2017-07-24 10:37 ` [kernel-hardening] " Dave Martin
2017-07-24 10:37 ` Dave Martin
2017-07-19 16:01 ` [PATCH 07/11] arm64: add basic pointer authentication support Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-25 15:26 ` Dave Martin
2017-07-25 15:26 ` [kernel-hardening] " Dave Martin
2017-07-25 15:26 ` Dave Martin
2017-07-25 15:26 ` Dave Martin
2017-08-11 7:46 ` Yao Qi
2017-08-11 7:46 ` [kernel-hardening] " Yao Qi
2017-08-11 7:46 ` Yao Qi
2017-08-11 8:45 ` Dave Martin
2017-08-11 8:45 ` [kernel-hardening] " Dave Martin
2017-08-11 8:45 ` Dave Martin
2017-08-11 8:45 ` Dave Martin
2017-07-19 16:01 ` [PATCH 08/11] arm64: expose user PAC bit positions via ptrace Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` [PATCH 09/11] arm64/kvm: preserve host HCR_EL2 value Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-08-01 11:00 ` Christoffer Dall
2017-08-01 11:00 ` [kernel-hardening] " Christoffer Dall
2017-08-01 11:00 ` Christoffer Dall
2017-08-01 11:00 ` Christoffer Dall
2017-07-19 16:01 ` [PATCH 10/11] arm64/kvm: context-switch ptrauth registers Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-08-01 11:00 ` Christoffer Dall
2017-08-01 11:00 ` [kernel-hardening] " Christoffer Dall
2017-08-01 11:00 ` Christoffer Dall
2017-08-01 11:00 ` Christoffer Dall
2017-08-01 14:26 ` Mark Rutland
2017-08-01 14:26 ` [kernel-hardening] " Mark Rutland
2017-08-01 14:26 ` Mark Rutland
2017-08-01 14:32 ` Will Deacon [this message]
2017-08-01 14:32 ` [kernel-hardening] " Will Deacon
2017-08-01 14:32 ` Will Deacon
2017-08-01 17:02 ` Christoffer Dall
2017-08-01 17:02 ` [kernel-hardening] " Christoffer Dall
2017-08-01 17:02 ` Christoffer Dall
2017-07-19 16:01 ` [PATCH 11/11] arm64: docs: document pointer authentication Mark Rutland
2017-07-19 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-19 16:01 ` Mark Rutland
2017-07-21 17:05 ` [PATCH 00/11] ARMv8.3 pointer authentication userspace support Dave Martin
2017-07-21 17:05 ` [kernel-hardening] " Dave Martin
2017-07-21 17:05 ` Dave Martin
2017-07-21 17:05 ` Dave Martin
2017-07-25 12:06 ` Mark Rutland
2017-07-25 12:06 ` [kernel-hardening] " Mark Rutland
2017-07-25 12:06 ` Mark Rutland
2017-07-25 14:00 ` Jiong Wang
2017-07-25 14:00 ` [kernel-hardening] " Jiong Wang
2017-07-25 14:00 ` Jiong Wang
2017-07-25 14:00 ` Jiong Wang
2017-08-11 11:29 ` Mark Rutland
2017-08-11 11:29 ` [kernel-hardening] " Mark Rutland
2017-08-11 11:29 ` Mark Rutland
2017-07-24 11:52 ` Yao Qi
2017-07-24 11:52 ` [kernel-hardening] " Yao Qi
2017-07-24 11:52 ` Yao Qi
2017-07-25 11:32 ` Yao Qi
2017-07-25 11:32 ` [kernel-hardening] " Yao Qi
2017-07-25 11:32 ` Yao Qi
2017-07-25 16:01 ` Mark Rutland
2017-07-25 16:01 ` [kernel-hardening] " Mark Rutland
2017-07-25 16:01 ` Mark Rutland
2017-07-25 14:12 ` [kernel-hardening] " Li Kun
2017-07-25 14:12 ` Li Kun
2017-07-25 14:12 ` Li Kun
2017-07-25 14:12 ` Li Kun
2017-07-25 15:12 ` Mark Rutland
2017-07-25 15:12 ` Mark Rutland
2017-07-25 15:12 ` Mark Rutland
2017-07-25 15:12 ` Mark Rutland
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