From: Dave Martin <Dave.Martin@arm.com>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: Amit Daniel Kachhap <amit.kachhap@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org,
Kristina Martsenko <kristina.martsenko@arm.com>,
Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v10 2/5] KVM: arm/arm64: context-switch ptrauth registers
Date: Wed, 24 Apr 2019 14:40:23 +0100 [thread overview]
Message-ID: <20190424134023.GV3567@e103592.cambridge.arm.com> (raw)
In-Reply-To: <09bd4e79-c507-1f00-01c5-38afb2a62077@arm.com>
On Wed, Apr 24, 2019 at 11:29:37AM +0100, Marc Zyngier wrote:
> On 23/04/2019 16:44, Dave Martin wrote:
> > On Tue, Apr 23, 2019 at 03:54:32PM +0530, Amit Daniel Kachhap wrote:
> >> Hi Mark,
> >>
> >> On 4/23/19 3:09 PM, Marc Zyngier wrote:
> >>> On Tue, 23 Apr 2019 05:42:35 +0100,
> >>> Amit Daniel Kachhap <amit.kachhap@arm.com> wrote:
[...]
> >>>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> >>>> index 7e34b9e..3cfe2eb 100644
> >>>> --- a/arch/arm64/Kconfig
> >>>> +++ b/arch/arm64/Kconfig
> >>>> @@ -1301,8 +1301,9 @@ config ARM64_PTR_AUTH
> >>>> context-switched along with the process.
> >>>> The feature is detected at runtime. If the feature is not present in
> >>>> - hardware it will not be advertised to userspace nor will it be
> >>>> - enabled.
> >>>> + hardware it will not be advertised to userspace/KVM guest nor will it
> >>>> + be enabled. However, KVM guest also require VHE mode and hence
> >>>> + CONFIG_ARM64_VHE=y option to use this feature.
> >>>
> >>> SVE seems to have the exact same requirements, and has
> >>>
> >>> depends on !KVM || ARM64_VHE
> >>>
> >>> Why don't we have that for PTR_AUTH too?
> >> This point came up earlier also and it was suggested by Dave[1] to leave
> >> userspace ptrauth for non-vhe mode as that would bring regression now.
> >> [1]:https://lkml.org/lkml/2019/3/27/583
> >
> > I see Marc applied this change in
> > https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git/commit/?h=queue&id=e19b245fa4c61558536bd34f80845f0c41eab65f0
>
> That's only for me not to forget anything, and it hasn't been folded
> into the original patch yet.
Ah, right, misunderstood.
> > The risk here is that someone has a custom config from an old kernel
> > that explicitly turns CONFIG_ARM64_VHE off, and that try to use that
> > config with this patch.
> >
> > I'm not sure how much we care about that.
> >
> > Otherwise, blocking this config so that people don't accidentally rely
> > on it seems sensible.
>
> What I'm trying to do is to reduce the amount of valid kernel
> configurations that we need to validate independently.
>
> At this stage, I'm tempted to just restrict it as described above, and
> maybe relax it if someone shouts at me.
Sounds good to me.
Cheers
---Dave
WARNING: multiple messages have this Message-ID (diff)
From: Dave Martin <Dave.Martin@arm.com>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org,
Kristina Martsenko <kristina.martsenko@arm.com>,
Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
Amit Daniel Kachhap <amit.kachhap@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v10 2/5] KVM: arm/arm64: context-switch ptrauth registers
Date: Wed, 24 Apr 2019 14:40:23 +0100 [thread overview]
Message-ID: <20190424134023.GV3567@e103592.cambridge.arm.com> (raw)
Message-ID: <20190424134023.SQTXP7g474TRvdkoyKhELV_YwytT3Gy8q6ma7xkJhx4@z> (raw)
In-Reply-To: <09bd4e79-c507-1f00-01c5-38afb2a62077@arm.com>
On Wed, Apr 24, 2019 at 11:29:37AM +0100, Marc Zyngier wrote:
> On 23/04/2019 16:44, Dave Martin wrote:
> > On Tue, Apr 23, 2019 at 03:54:32PM +0530, Amit Daniel Kachhap wrote:
> >> Hi Mark,
> >>
> >> On 4/23/19 3:09 PM, Marc Zyngier wrote:
> >>> On Tue, 23 Apr 2019 05:42:35 +0100,
> >>> Amit Daniel Kachhap <amit.kachhap@arm.com> wrote:
[...]
> >>>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> >>>> index 7e34b9e..3cfe2eb 100644
> >>>> --- a/arch/arm64/Kconfig
> >>>> +++ b/arch/arm64/Kconfig
> >>>> @@ -1301,8 +1301,9 @@ config ARM64_PTR_AUTH
> >>>> context-switched along with the process.
> >>>> The feature is detected at runtime. If the feature is not present in
> >>>> - hardware it will not be advertised to userspace nor will it be
> >>>> - enabled.
> >>>> + hardware it will not be advertised to userspace/KVM guest nor will it
> >>>> + be enabled. However, KVM guest also require VHE mode and hence
> >>>> + CONFIG_ARM64_VHE=y option to use this feature.
> >>>
> >>> SVE seems to have the exact same requirements, and has
> >>>
> >>> depends on !KVM || ARM64_VHE
> >>>
> >>> Why don't we have that for PTR_AUTH too?
> >> This point came up earlier also and it was suggested by Dave[1] to leave
> >> userspace ptrauth for non-vhe mode as that would bring regression now.
> >> [1]:https://lkml.org/lkml/2019/3/27/583
> >
> > I see Marc applied this change in
> > https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git/commit/?h=queue&id=e19b245fa4c61558536bd34f80845f0c41eab65f0
>
> That's only for me not to forget anything, and it hasn't been folded
> into the original patch yet.
Ah, right, misunderstood.
> > The risk here is that someone has a custom config from an old kernel
> > that explicitly turns CONFIG_ARM64_VHE off, and that try to use that
> > config with this patch.
> >
> > I'm not sure how much we care about that.
> >
> > Otherwise, blocking this config so that people don't accidentally rely
> > on it seems sensible.
>
> What I'm trying to do is to reduce the amount of valid kernel
> configurations that we need to validate independently.
>
> At this stage, I'm tempted to just restrict it as described above, and
> maybe relax it if someone shouts at me.
Sounds good to me.
Cheers
---Dave
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kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply other threads:[~2019-04-24 13:40 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-23 4:42 [PATCH v10 0/5] Add ARMv8.3 pointer authentication for kvm guest Amit Daniel Kachhap
2019-04-23 4:42 ` Amit Daniel Kachhap
2019-04-23 4:42 ` [PATCH v10 1/5] KVM: arm64: Add a vcpu flag to control ptrauth for guest Amit Daniel Kachhap
2019-04-23 4:42 ` Amit Daniel Kachhap
2019-04-23 15:44 ` Dave Martin
2019-04-23 15:44 ` Dave Martin
2019-04-24 5:57 ` Amit Daniel Kachhap
2019-04-24 5:57 ` Amit Daniel Kachhap
2019-04-24 13:42 ` Dave Martin
2019-04-24 13:42 ` Dave Martin
2019-04-23 4:42 ` [PATCH v10 2/5] KVM: arm/arm64: context-switch ptrauth registers Amit Daniel Kachhap
2019-04-23 4:42 ` Amit Daniel Kachhap
2019-04-23 9:39 ` Marc Zyngier
2019-04-23 9:39 ` Marc Zyngier
2019-04-23 10:24 ` Amit Daniel Kachhap
2019-04-23 10:24 ` Amit Daniel Kachhap
2019-04-23 15:44 ` Dave Martin
2019-04-23 15:44 ` Dave Martin
2019-04-24 10:29 ` Marc Zyngier
2019-04-24 10:29 ` Marc Zyngier
2019-04-24 13:40 ` Dave Martin [this message]
2019-04-24 13:40 ` Dave Martin
2019-04-24 13:39 ` Dave Martin
2019-04-24 13:39 ` Dave Martin
2019-04-24 14:29 ` Marc Zyngier
2019-04-24 14:29 ` Marc Zyngier
2019-04-24 14:30 ` Dave P Martin
2019-04-24 14:30 ` Dave P Martin
2019-04-23 4:42 ` [PATCH v10 3/5] KVM: arm64: Add userspace flag to enable pointer authentication Amit Daniel Kachhap
2019-04-23 4:42 ` Amit Daniel Kachhap
2019-04-23 15:45 ` Dave Martin
2019-04-23 15:45 ` Dave Martin
2019-04-24 6:39 ` Amit Daniel Kachhap
2019-04-24 6:39 ` Amit Daniel Kachhap
2019-04-23 4:42 ` [PATCH v10 4/5] KVM: arm64: Add capability to advertise ptrauth for guest Amit Daniel Kachhap
2019-04-23 4:42 ` Amit Daniel Kachhap
2019-04-23 15:45 ` Dave Martin
2019-04-23 15:45 ` Dave Martin
2019-04-23 4:42 ` [kvmtool PATCH v10 5/5] KVM: arm/arm64: Add a vcpu feature for pointer authentication Amit Daniel Kachhap
2019-04-23 4:42 ` Amit Daniel Kachhap
2019-04-23 15:46 ` Dave Martin
2019-04-23 15:46 ` Dave Martin
2019-04-24 7:02 ` Amit Daniel Kachhap
2019-04-24 7:02 ` Amit Daniel Kachhap
2019-04-24 13:41 ` Dave Martin
2019-04-24 13:41 ` Dave Martin
2019-05-28 10:11 ` Dave Martin
2019-05-28 12:48 ` Amit Daniel Kachhap
2019-05-28 13:38 ` Dave Martin
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