Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751981AbdIMPrI (ORCPT ); Wed, 13 Sep 2017 11:47:08 -0400 Received: from foss.arm.com ([217.140.101.70]:53002 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751860AbdIMPrD (ORCPT ); Wed, 13 Sep 2017 11:47:03 -0400 Subject: Re: [RFC PATCH 6/6] iommu/arm-smmu-v3: Avoid ILLEGAL setting of STE.S1STALLD and CD.S To: Yisheng Xie , Will Deacon Cc: "joro@8bytes.org" , "robh+dt@kernel.org" , Mark Rutland , Lorenzo Pieralisi , "hanjun.guo@linaro.org" , Sudeep Holla , "rjw@rjwysocki.net" , "lenb@kernel.org" , Robin Murphy , "robert.moore@intel.com" , "lv.zheng@intel.com" , "iommu@lists.linux-foundation.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "devel@acpica.org" , "liubo95@huawei.com" , "chenjiankang1@huawei.com" References: <1504167642-14922-1-git-send-email-xieyisheng1@huawei.com> <1504167642-14922-7-git-send-email-xieyisheng1@huawei.com> <738977bb-4cd7-7d86-0ea0-0c88b6af721c@arm.com> <20170913030643.GD12411@arm.com> <2f952821-afc3-46dd-17eb-40e8626bd6e5@huawei.com> From: Jean-Philippe Brucker Message-ID: Date: Wed, 13 Sep 2017 16:47:27 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <2f952821-afc3-46dd-17eb-40e8626bd6e5@huawei.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2737 Lines: 65 On 13/09/17 11:11, Yisheng Xie wrote: > Hi Will, > > On 2017/9/13 11:06, Will Deacon wrote: >> On Tue, Sep 05, 2017 at 01:54:19PM +0100, Jean-Philippe Brucker wrote: >>> On 31/08/17 09:20, Yisheng Xie wrote: >>>> It is ILLEGAL to set STE.S1STALLD if STALL_MODEL is not 0b00, which >>>> means we should not disable stall mode if stall/terminate mode is not >>>> configuable. >>>> >>>> Meanwhile, it is also ILLEGAL when STALL_MODEL==0b10 && CD.S==0 which >>>> means if stall mode is force we should always set CD.S. >>>> >>>> This patch add ARM_SMMU_FEAT_TERMINATE feature bit for smmu, and use >>>> TERMINATE feature checking to ensue above ILLEGAL cases from happening. >>>> >>>> Signed-off-by: Yisheng Xie >>>> --- >>>>? drivers/iommu/arm-smmu-v3.c | 22 ++++++++++++++++------ >>>>? 1 file changed, 16 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c >>>> index dbda2eb..0745522 100644 >>>> --- a/drivers/iommu/arm-smmu-v3.c >>>> +++ b/drivers/iommu/arm-smmu-v3.c >>>> @@ -55,6 +55,7 @@ >>>>? #define IDR0_STALL_MODEL_SHIFT???????????? 24 >>>>? #define IDR0_STALL_MODEL_MASK????????????? 0x3 >>>>? #define IDR0_STALL_MODEL_STALL???????????? (0 << IDR0_STALL_MODEL_SHIFT) >>>> +#define IDR0_STALL_MODEL_NS??????????????? (1 << IDR0_STALL_MODEL_SHIFT) >>>>? #define IDR0_STALL_MODEL_FORCE???????????? (2 << IDR0_STALL_MODEL_SHIFT) >>>>? #define IDR0_TTENDIAN_SHIFT??????????????? 21 >>>>? #define IDR0_TTENDIAN_MASK???????? 0x3 >>>> @@ -766,6 +767,7 @@ struct arm_smmu_device { >>>>? #define ARM_SMMU_FEAT_SVM????????? (1 << 15) >>>>? #define ARM_SMMU_FEAT_HA?????????? (1 << 16) >>>>? #define ARM_SMMU_FEAT_HD?????????? (1 << 17) >>>> +#define ARM_SMMU_FEAT_TERMINATE??????????? (1 << 18) >>> >>> I'd rather introduce something like "ARM_SMMU_FEAT_STALL_FORCE" instead. >>> Terminate model has another meaning, and is defined by a different bit in >>> IDR0. >> >> Yes. What we need to do is: >> >> - If STALL_MODEL is 0b00, then set S1STALLD > > Yes, and within this case, we can only set the S1STALLD for masters which can > not stall in the future? > >> - If STALL_MODEL is 0b01, then we're ok (in future, avoiding trying to use >>?? stalls, even for masters that claim to support it) >> - If STALL_MODEL is 0b10, then force all PCI devices and any platform >>?? devices that don't claim to support stalls into bypass (depending on >>?? disable_bypass). >> >> Reasonable? We could actually knock up a fix for mainline to do most of >> this already. > This sound reasonable to me. And I can be a volunteer to prepare this patch if > Jean-Philippe do not oppose :) Sure go ahead, I'll rebase the platform SVM work on top of it. Thanks, Jean