From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 04E5F611B for ; Thu, 15 Jun 2023 09:51:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 676D6C433C0; Thu, 15 Jun 2023 09:51:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686822705; bh=LM3vizWVElx+XfZb1koUqZg3HSV3Fg3PE1hrl5+LRp0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=bzsuyyxMQlSLtVRMItcciPoEa51HDduUY67+4FH6T9eqX5DL5rykCB57E8j22ySOI fEInuWSONKmCE3dZWGG5uXQWiXxltaXOOujHPc9rUy+ANFzJKbux1OTjaF+lukND6+ CVW2XmdhclNq6hjeBaqVGAZULGtsINeD+xzENFX8nQq0/HHKUqLoF48sEkTxea5sJN 7X9qy7AaqhTVQHU3DCyr5LUwECyPUcHB+3TVp0tDa9owbnPQDBdW3imxwO+xVGM9GE eFJ6NZQ/ChA7ndOLb+qDKjykXX0ZztXg+AvmBQxOWsGJHpWR9Go9NBSb00miTpbqUn myC6vOkzOc1Ow== Received: from [213.175.39.66] (helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1q9jdm-005ZDI-Ha; Thu, 15 Jun 2023 10:51:43 +0100 Date: Thu, 15 Jun 2023 10:51:42 +0100 Message-ID: <87a5x1qci9.wl-maz@kernel.org> From: Marc Zyngier To: Oliver Upton Cc: kvmarm@lists.linux.dev, James Morse , Suzuki K Poulose , Zenghui Yu , Will Deacon , Catalin Marinas , linux-arm-kernel@lists.infradead.org, Darren Hart , D Scott Phillips Subject: Re: [PATCH 0/3] KVM: arm64: Work around Ampere1 erratum AC03_CPU_38 In-Reply-To: <20230609220104.1836988-1-oliver.upton@linux.dev> References: <20230609220104.1836988-1-oliver.upton@linux.dev> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/28.2 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 213.175.39.66 X-SA-Exim-Rcpt-To: oliver.upton@linux.dev, kvmarm@lists.linux.dev, james.morse@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, will@kernel.org, catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, darren@os.amperecomputing.com, scott@os.amperecomputing.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Fri, 09 Jun 2023 23:01:01 +0100, Oliver Upton wrote: > > Hi folks, > > Small series to work around a CPU erratum on AmpereOne. While the > implementation does not advertise support for FEAT_HAFDBS (due to > another erratum), the associated control bits do not have RES0 behavior > as required by the architecture. > > Usage of HAFDBS at stage-1 is unaffected, since HA and HD are only > enabled on implementations that advertise the feature. However, KVM > relies on HA having RES0 semantics if the feature isn't implemented. The > end result is that KVM enables a broken hardware access flag > implementation that could lead to correctness issues. > > Applies to 6.4-rc1. Tested with access_tracking_perf_test, verifying > that KVM is indeed taking Access Flag faults. For the series: Reviewed-by: Marc Zyngier M. -- Without deviation from the norm, progress is not possible.