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[209.51.188.17]) by mx.google.com with ESMTPS id r123si2335725iod.69.2021.03.11.02.00.28 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 11 Mar 2021 02:00:29 -0800 (PST) Received-SPF: pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; spf=pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from localhost ([::1]:36474 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lKI7I-0001nC-Ci for alex.bennee@linaro.org; Thu, 11 Mar 2021 05:00:28 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:35124) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lKI6b-0001kN-6q; Thu, 11 Mar 2021 04:59:45 -0500 Received: from mail.kernel.org ([198.145.29.99]:39622) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lKI6Z-0000Lg-A6; Thu, 11 Mar 2021 04:59:44 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 101A464E28; Thu, 11 Mar 2021 09:59:40 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lKI6T-000xac-SU; Thu, 11 Mar 2021 09:59:38 +0000 Date: Thu, 11 Mar 2021 09:59:37 +0000 Message-ID: <87pn06f1ti.wl-maz@kernel.org> From: Marc Zyngier To: Andrew Jones Subject: Re: [PATCH v2 2/2] hw/arm/virt: KVM: The IPA lower bound is 32 In-Reply-To: <20210310135218.255205-3-drjones@redhat.com> References: <20210310135218.255205-1-drjones@redhat.com> <20210310135218.255205-3-drjones@redhat.com> 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/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: drjones@redhat.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, pbonzini@redhat.com, peter.maydell@linaro.org, eric.auger@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Received-SPF: pass client-ip=198.145.29.99; envelope-from=maz@kernel.org; helo=mail.kernel.org X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pbonzini@redhat.com, qemu-arm@nongnu.org, qemu-devel@nongnu.org, eric.auger@redhat.com, peter.maydell@linaro.org Errors-To: qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org Sender: "Qemu-devel" X-TUID: j1HSFJ38rnYh On Wed, 10 Mar 2021 13:52:18 +0000, Andrew Jones wrote: > > The virt machine already checks KVM_CAP_ARM_VM_IPA_SIZE to get the > upper bound of the IPA size. If that bound is lower than the highest > possible GPA for the machine, then QEMU will error out. However, the > IPA is set to 40 when the highest GPA is less than or equal to 40, > even when KVM may support an IPA limit as low as 32. This means KVM > may fail the VM creation unnecessarily. Additionally, 40 is selected > with the value 0, which means use the default, and that gets around > a check in some versions of KVM, causing a difficult to debug fail. > Always use the IPA size that corresponds to the highest possible GPA, > unless it's lower than 32, in which case use 32. Also, we must still > use 0 when KVM only supports the legacy fixed 40 bit IPA. > > Suggested-by: Marc Zyngier > Signed-off-by: Andrew Jones Reviewed-by: Marc Zyngier M. -- Without deviation from the norm, progress is not possible.