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From: Andrew Murray <andrew.murray@arm.com>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Subject: Re: [PATCH 0/3] arm64: KVM: Allow direct function calls on VHE
Date: Wed, 9 Jan 2019 14:11:36 +0000	[thread overview]
Message-ID: <20190109141135.GG56789@e119886-lin.cambridge.arm.com> (raw)
In-Reply-To: <20190109135435.178664-1-marc.zyngier@arm.com>

On Wed, Jan 09, 2019 at 01:54:32PM +0000, Marc Zyngier wrote:
> It recently appeared that the nasty hack we use to call a HYP function
> on a non-VHE system has an interesting side effect on VHE: We wrap any
> such call into a hypercall, losing any form of type checking between
> the caller and the callee.
> 
> This isn't a big deal if you can guarantee to write code that is
> always 100% correct, but it appears that I'm not you.
> 
> In order to restore some sanity, let's use the following property: On
> a VHE system, it is always possible to call any function directly as
> they live in the same address space. We can thus always emit a direct
> call, and use a static key to flip from one to the other. As a bonus,
> this also sanitizes !VHE systems as we always generate code for noth

s/noth/both/g

Andrew Murray

> revisions of the architecture.
> 
> Marc Zyngier (3):
>   arm/arm64: KVM: Introduce kvm_call_hyp_ret()
>   arm64: KVM: Allow for direct call of HYP functions when using VHE
>   arm64: KVM: Drop VHE-specific HYP call stub
> 
>  arch/arm/include/asm/kvm_host.h   |  3 +++
>  arch/arm64/include/asm/kvm_host.h | 31 ++++++++++++++++++++++++++++++-
>  arch/arm64/kvm/debug.c            |  2 +-
>  arch/arm64/kvm/hyp.S              |  3 ---
>  arch/arm64/kvm/hyp/hyp-entry.S    | 12 ------------
>  virt/kvm/arm/arm.c                |  2 +-
>  virt/kvm/arm/vgic/vgic-v3.c       |  4 ++--
>  7 files changed, 37 insertions(+), 20 deletions(-)
> 
> -- 
> 2.20.1
> 
> _______________________________________________
> kvmarm mailing list
> kvmarm@lists.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Andrew Murray <andrew.murray@arm.com>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Subject: Re: [PATCH 0/3] arm64: KVM: Allow direct function calls on VHE
Date: Wed, 9 Jan 2019 14:11:36 +0000	[thread overview]
Message-ID: <20190109141135.GG56789@e119886-lin.cambridge.arm.com> (raw)
In-Reply-To: <20190109135435.178664-1-marc.zyngier@arm.com>

On Wed, Jan 09, 2019 at 01:54:32PM +0000, Marc Zyngier wrote:
> It recently appeared that the nasty hack we use to call a HYP function
> on a non-VHE system has an interesting side effect on VHE: We wrap any
> such call into a hypercall, losing any form of type checking between
> the caller and the callee.
> 
> This isn't a big deal if you can guarantee to write code that is
> always 100% correct, but it appears that I'm not you.
> 
> In order to restore some sanity, let's use the following property: On
> a VHE system, it is always possible to call any function directly as
> they live in the same address space. We can thus always emit a direct
> call, and use a static key to flip from one to the other. As a bonus,
> this also sanitizes !VHE systems as we always generate code for noth

s/noth/both/g

Andrew Murray

> revisions of the architecture.
> 
> Marc Zyngier (3):
>   arm/arm64: KVM: Introduce kvm_call_hyp_ret()
>   arm64: KVM: Allow for direct call of HYP functions when using VHE
>   arm64: KVM: Drop VHE-specific HYP call stub
> 
>  arch/arm/include/asm/kvm_host.h   |  3 +++
>  arch/arm64/include/asm/kvm_host.h | 31 ++++++++++++++++++++++++++++++-
>  arch/arm64/kvm/debug.c            |  2 +-
>  arch/arm64/kvm/hyp.S              |  3 ---
>  arch/arm64/kvm/hyp/hyp-entry.S    | 12 ------------
>  virt/kvm/arm/arm.c                |  2 +-
>  virt/kvm/arm/vgic/vgic-v3.c       |  4 ++--
>  7 files changed, 37 insertions(+), 20 deletions(-)
> 
> -- 
> 2.20.1
> 
> _______________________________________________
> kvmarm mailing list
> kvmarm@lists.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

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  parent reply	other threads:[~2019-01-09 14:11 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-09 13:54 [PATCH 0/3] arm64: KVM: Allow direct function calls on VHE Marc Zyngier
2019-01-09 13:54 ` Marc Zyngier
2019-01-09 13:54 ` [PATCH 1/3] arm/arm64: KVM: Introduce kvm_call_hyp_ret() Marc Zyngier
2019-01-09 13:54   ` Marc Zyngier
2019-01-09 13:54 ` [PATCH 2/3] arm64: KVM: Allow for direct call of HYP functions when using VHE Marc Zyngier
2019-01-09 13:54   ` Marc Zyngier
2019-01-09 14:24   ` Andrew Murray
2019-01-09 14:24     ` Andrew Murray
2019-01-09 14:45     ` Marc Zyngier
2019-01-09 14:45       ` Marc Zyngier
2019-01-09 14:51       ` Julien Thierry
2019-01-09 14:51         ` Julien Thierry
2019-01-09 14:52         ` Julien Thierry
2019-01-09 14:52           ` Julien Thierry
2019-01-09 16:01         ` Marc Zyngier
2019-01-09 16:01           ` Marc Zyngier
2019-01-09 16:04           ` Andrew Murray
2019-01-09 16:04             ` Andrew Murray
2019-01-09 13:54 ` [PATCH 3/3] arm64: KVM: Drop VHE-specific HYP call stub Marc Zyngier
2019-01-09 13:54   ` Marc Zyngier
2019-01-09 14:11 ` Andrew Murray [this message]
2019-01-09 14:11   ` [PATCH 0/3] arm64: KVM: Allow direct function calls on VHE Andrew Murray

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