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From: Marc Zyngier <maz@kernel.org>
To: Kalesh Singh <kaleshsingh@google.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>,
	will@kernel.org, Peter Collingbourne <pcc@google.com>,
	kernel-team@android.com, linux-kernel@vger.kernel.org,
	Joey Gouly <joey.gouly@arm.com>,
	kvmarm@lists.cs.columbia.edu, Andrew Walbran <qwandor@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	surenb@google.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/7] KVM: arm64: Hypervisor stack enhancements
Date: Mon, 14 Feb 2022 11:41:14 +0000	[thread overview]
Message-ID: <87mtit4qw5.wl-maz@kernel.org> (raw)
In-Reply-To: <20220210224220.4076151-1-kaleshsingh@google.com>

On Thu, 10 Feb 2022 22:41:41 +0000,
Kalesh Singh <kaleshsingh@google.com> wrote:
> 
> This series is based on v5.17-rc3 and adds the following stack features to
> the KVM nVHE hypervisor:
> 
> == Hyp Stack Guard Pages ==
> 
> Based on the technique used by arm64 VMAP_STACK to detect overflow.
> i.e. the stack is aligned to twice its size which ensure that the 
> 'stack shift' bit of any valid SP is 0. The 'stack shift' bit can be
> tested in the exception entry to detect overflow without corrupting GPRs.

Having quickly parsed the code, this seems to only be effective for
pKVM and the EL2-allocated stack. Is there any technical reason not to
implement this for the much more common case of 'classic' KVM in nVHE
mode?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.
_______________________________________________
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: Marc Zyngier <maz@kernel.org>
To: Kalesh Singh <kaleshsingh@google.com>
Cc: will@kernel.org, qperret@google.com, tabba@google.com,
	surenb@google.com, kernel-team@android.com,
	Catalin Marinas <catalin.marinas@arm.com>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Pasha Tatashin <pasha.tatashin@soleen.com>,
	Joey Gouly <joey.gouly@arm.com>,
	Peter Collingbourne <pcc@google.com>,
	Andrew Walbran <qwandor@google.com>,
	Andrew Scull <ascull@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH 0/7] KVM: arm64: Hypervisor stack enhancements
Date: Mon, 14 Feb 2022 11:41:14 +0000	[thread overview]
Message-ID: <87mtit4qw5.wl-maz@kernel.org> (raw)
In-Reply-To: <20220210224220.4076151-1-kaleshsingh@google.com>

On Thu, 10 Feb 2022 22:41:41 +0000,
Kalesh Singh <kaleshsingh@google.com> wrote:
> 
> This series is based on v5.17-rc3 and adds the following stack features to
> the KVM nVHE hypervisor:
> 
> == Hyp Stack Guard Pages ==
> 
> Based on the technique used by arm64 VMAP_STACK to detect overflow.
> i.e. the stack is aligned to twice its size which ensure that the 
> 'stack shift' bit of any valid SP is 0. The 'stack shift' bit can be
> tested in the exception entry to detect overflow without corrupting GPRs.

Having quickly parsed the code, this seems to only be effective for
pKVM and the EL2-allocated stack. Is there any technical reason not to
implement this for the much more common case of 'classic' KVM in nVHE
mode?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Kalesh Singh <kaleshsingh@google.com>
Cc: will@kernel.org, qperret@google.com, tabba@google.com,
	surenb@google.com, kernel-team@android.com,
	Catalin Marinas <catalin.marinas@arm.com>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Pasha Tatashin <pasha.tatashin@soleen.com>,
	Joey Gouly <joey.gouly@arm.com>,
	Peter Collingbourne <pcc@google.com>,
	Andrew Walbran <qwandor@google.com>,
	Andrew Scull <ascull@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH 0/7] KVM: arm64: Hypervisor stack enhancements
Date: Mon, 14 Feb 2022 11:41:14 +0000	[thread overview]
Message-ID: <87mtit4qw5.wl-maz@kernel.org> (raw)
In-Reply-To: <20220210224220.4076151-1-kaleshsingh@google.com>

On Thu, 10 Feb 2022 22:41:41 +0000,
Kalesh Singh <kaleshsingh@google.com> wrote:
> 
> This series is based on v5.17-rc3 and adds the following stack features to
> the KVM nVHE hypervisor:
> 
> == Hyp Stack Guard Pages ==
> 
> Based on the technique used by arm64 VMAP_STACK to detect overflow.
> i.e. the stack is aligned to twice its size which ensure that the 
> 'stack shift' bit of any valid SP is 0. The 'stack shift' bit can be
> tested in the exception entry to detect overflow without corrupting GPRs.

Having quickly parsed the code, this seems to only be effective for
pKVM and the EL2-allocated stack. Is there any technical reason not to
implement this for the much more common case of 'classic' KVM in nVHE
mode?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

  parent reply	other threads:[~2022-02-14 11:41 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-10 22:41 [PATCH 0/7] KVM: arm64: Hypervisor stack enhancements Kalesh Singh
2022-02-10 22:41 ` Kalesh Singh
2022-02-10 22:41 ` Kalesh Singh
2022-02-10 22:41 ` [PATCH 1/7] KVM: arm64: Map the stack pages in the 'private' range Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41 ` [PATCH 2/7] KVM: arm64: Factor out private range VA allocation Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41 ` [PATCH 3/7] arm64: asm: Introduce test_sp_overflow macro Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41 ` [PATCH 4/7] KVM: arm64: Allocate guard pages near hyp stacks Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-14 14:06   ` Marc Zyngier
2022-02-14 14:06     ` Marc Zyngier
2022-02-14 14:06     ` Marc Zyngier
2022-02-14 22:03     ` Kalesh Singh
2022-02-14 22:03       ` Kalesh Singh
2022-02-14 22:03       ` Kalesh Singh
2022-02-10 22:41 ` [PATCH 5/7] KVM: arm64: Add Hyp overflow stack Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41 ` [PATCH 6/7] KVM: arm64: Unwind and dump nVHE HYP stacktrace Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41 ` [PATCH 7/7] KVM: arm64: Symbolize the nVHE HYP backtrace Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-10 22:41   ` Kalesh Singh
2022-02-14 11:41 ` Marc Zyngier [this message]
2022-02-14 11:41   ` [PATCH 0/7] KVM: arm64: Hypervisor stack enhancements Marc Zyngier
2022-02-14 11:41   ` Marc Zyngier
2022-02-14 21:54   ` Kalesh Singh
2022-02-14 21:54     ` Kalesh Singh
2022-02-14 21:54     ` Kalesh Singh

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