From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
David Brazdil <dbrazdil@google.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: Re: [PATCH 00/19] Fix and rewrite arm64 spectre mitigations
Date: Fri, 18 Sep 2020 17:59:20 +0100 [thread overview]
Message-ID: <20200918165919.GA32047@willie-the-truck> (raw)
In-Reply-To: <20200918164729.31994-1-will@kernel.org>
On the off-chance that anybody's reading this...
On Fri, Sep 18, 2020 at 05:47:10PM +0100, Will Deacon wrote:
> The temptation was to remove the code entirely, but after putting in
> some effort to untangle it, we ended up knocking it into a much better
> shape. Although that doesn't change the fact that we can't test it very
> well, it certainly appears to behave better than the old code in situations
> such as:
>
> - Err... wanting mitigation on more than one CPU
>
> - Not changing the mitigation state at runtime (i.e. after userspace
> has started running)
>
> - Gracefully handling failure to bring late CPUs online (previously
> this would only happen _after_ updating the mitigation state!)
>
> - Clear separation between mitigation state (am I vulnerable?) and
> policy (the user wants to go fast)
>
> - Removal of the hideously expensive "dynamic" Spectre-v2 mitigation
> for KVM guests
^^^ This should be 'hideously expensive "dynamic" Spectre-v4 mitigation'.
The firmware call itself is helpfully named "workaround 2", so I always
get them mixed up.
Will
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prev parent reply other threads:[~2020-09-18 17:01 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-18 16:47 [PATCH 00/19] Fix and rewrite arm64 spectre mitigations Will Deacon
2020-09-18 16:47 ` [PATCH 01/19] arm64: Make use of ARCH_WORKAROUND_1 even when KVM is not enabled Will Deacon
2020-09-18 16:47 ` [PATCH 02/19] arm64: Run ARCH_WORKAROUND_1 enabling code on all CPUs Will Deacon
2020-09-21 12:54 ` Sasha Levin
2020-09-18 16:47 ` [PATCH 03/19] arm64: Run ARCH_WORKAROUND_2 " Will Deacon
2020-09-18 17:13 ` Suzuki K Poulose
2020-09-18 16:47 ` [PATCH 04/19] arm64: Remove Spectre-related CONFIG_* options Will Deacon
2020-09-18 16:47 ` [PATCH 05/19] KVM: arm64: Replace CONFIG_KVM_INDIRECT_VECTORS with CONFIG_RANDOMIZE_BASE Will Deacon
2020-09-18 16:47 ` [PATCH 06/19] KVM: arm64: Simplify install_bp_hardening_cb() Will Deacon
2020-09-18 16:47 ` [PATCH 07/19] arm64: Rename ARM64_HARDEN_BRANCH_PREDICTOR to ARM64_SPECTRE_V2 Will Deacon
2020-09-18 16:47 ` [PATCH 08/19] arm64: Introduce separate file for spectre mitigations and reporting Will Deacon
2020-09-18 16:47 ` [PATCH 09/19] arm64: Rewrite Spectre-v2 mitigation code Will Deacon
2020-09-18 16:47 ` [PATCH 10/19] KVM: arm64: Set CSV2 for guests on hardware unaffected by Spectre-v2 Will Deacon
2020-09-18 16:47 ` [PATCH 11/19] arm64: Group start_thread() functions together Will Deacon
2020-09-18 16:47 ` [PATCH 12/19] arm64: Treat SSBS as a non-strict system feature Will Deacon
2020-09-18 16:47 ` [PATCH 13/19] arm64: Rename ARM64_SSBD to ARM64_SPECTRE_V4 Will Deacon
2020-09-18 16:47 ` [PATCH 14/19] arm64: Move SSBD prctl() handler alongside other spectre mitigation code Will Deacon
2020-09-18 16:47 ` [PATCH 15/19] arm64: Rewrite Spectre-v4 " Will Deacon
2020-09-18 16:47 ` [PATCH 16/19] KVM: arm64: Simplify handling of ARCH_WORKAROUND_2 Will Deacon
2020-09-18 16:47 ` [PATCH 17/19] KVM: arm64: Get rid of kvm_arm_have_ssbd() Will Deacon
2020-09-18 16:47 ` [PATCH 18/19] KVM: arm64: Convert ARCH_WORKAROUND_2 to arm64_get_spectre_v4_state() Will Deacon
2020-09-18 16:47 ` [PATCH 19/19] arm64: Get rid of arm64_ssbd_state Will Deacon
2020-09-18 16:59 ` Will Deacon [this message]
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