From: Will Deacon <will@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
kernel-team@android.com, James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>
Subject: Re: [PATCH] KVM: arm64: Ensure I-cache isolation between vcpus of a same VM
Date: Tue, 9 Mar 2021 13:26:46 +0000 [thread overview]
Message-ID: <20210309132645.GA28297@willie-the-truck> (raw)
In-Reply-To: <20210303164505.68492-1-maz@kernel.org>
On Wed, Mar 03, 2021 at 04:45:05PM +0000, Marc Zyngier wrote:
> It recently became apparent that the ARMv8 architecture has interesting
> rules regarding attributes being used when fetching instructions
> if the MMU is off at Stage-1.
>
> In this situation, the CPU is allowed to fetch from the PoC and
> allocate into the I-cache (unless the memory is mapped with
> the XN attribute at Stage-2).
>
> If we transpose this to vcpus sharing a single physical CPU,
> it is possible for a vcpu running with its MMU off to influence
> another vcpu running with its MMU on, as the latter is expected to
> fetch from the PoU (and self-patching code doesn't flush below that
> level).
>
> In order to solve this, reuse the vcpu-private TLB invalidation
> code to apply the same policy to the I-cache, nuking it every time
> the vcpu runs on a physical CPU that ran another vcpu of the same
> VM in the past.
>
> This involve renaming __kvm_tlb_flush_local_vmid() to
> __kvm_flush_cpu_context(), and inserting a local i-cache invalidation
> there.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> arch/arm64/include/asm/kvm_asm.h | 4 ++--
> arch/arm64/kvm/arm.c | 7 ++++++-
> arch/arm64/kvm/hyp/nvhe/hyp-main.c | 6 +++---
> arch/arm64/kvm/hyp/nvhe/tlb.c | 3 ++-
> arch/arm64/kvm/hyp/vhe/tlb.c | 3 ++-
> 5 files changed, 15 insertions(+), 8 deletions(-)
Since the FWB discussion doesn't affect the correctness of this patch:
Acked-by: Will Deacon <will@kernel.org>
Will
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next prev parent reply other threads:[~2021-03-09 13:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-03 16:45 [PATCH] KVM: arm64: Ensure I-cache isolation between vcpus of a same VM Marc Zyngier
2021-03-05 19:07 ` Catalin Marinas
2021-03-06 10:54 ` Marc Zyngier
2021-03-06 14:15 ` Catalin Marinas
2021-03-08 16:53 ` Alexandru Elisei
2021-03-08 20:03 ` Marc Zyngier
2021-03-09 17:07 ` Alexandru Elisei
2021-03-09 13:26 ` Will Deacon [this message]
2021-03-09 14:38 ` Catalin Marinas
2021-03-09 18:01 ` Marc Zyngier
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