From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yisheng Xie Subject: Re: [RFCv2 PATCH 14/36] iommu/arm-smmu-v3: Add support for Substream IDs Date: Fri, 3 Nov 2017 13:45:26 +0800 Message-ID: <37a82eaa-dc9d-af98-6cb8-941ca925b838@huawei.com> References: <20171006133203.22803-1-jean-philippe.brucker@arm.com> <20171006133203.22803-15-jean-philippe.brucker@arm.com> <5FC3163CFD30C246ABAA99954A238FA838454887@FRAEML521-MBX.china.huawei.com> <20171102155152.GA11899@e106794-lin.localdomain> <5FC3163CFD30C246ABAA99954A238FA838454A9B@FRAEML521-MBX.china.huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from szxga04-in.huawei.com ([45.249.212.190]:9947 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750722AbdKCFrZ (ORCPT ); Fri, 3 Nov 2017 01:47:25 -0400 In-Reply-To: <5FC3163CFD30C246ABAA99954A238FA838454A9B@FRAEML521-MBX.china.huawei.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Shameerali Kolothum Thodi , Jean-Philippe Brucker Cc: "linux-arm-kernel@lists.infradead.org" , "linux-pci@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "devicetree@vger.kernel.org" , "iommu@lists.linux-foundation.org" , Mark Rutland , Gabriele Paoloni , Catalin Marinas , Will Deacon , "okaya@codeaurora.org" , "yi.l.liu@intel.com" , Lorenzo Pieralisi , "ashok.raj@intel.com" , "tn@semihalf.com" , "joro@8bytes.org" , "rfranz@cavium.com" Hi Jean, On 2017/11/3 1:02, Shameerali Kolothum Thodi wrote: > > >> -----Original Message----- >> From: Jean-Philippe Brucker [mailto:Jean-Philippe.Brucker@arm.com] >> Sent: Thursday, November 02, 2017 3:52 PM >> To: Shameerali Kolothum Thodi >> Cc: linux-arm-kernel@lists.infradead.org; linux-pci@vger.kernel.org; linux- >> acpi@vger.kernel.org; devicetree@vger.kernel.org; iommu@lists.linux- >> foundation.org; Mark Rutland ; xieyisheng (A) >> ; Gabriele Paoloni >> ; Catalin Marinas >> ; Will Deacon ; >> okaya@codeaurora.org; yi.l.liu@intel.com; Lorenzo Pieralisi >> ; ashok.raj@intel.com; tn@semihalf.com; >> joro@8bytes.org; rfranz@cavium.com; lenb@kernel.org; >> jacob.jun.pan@linux.intel.com; alex.williamson@redhat.com; >> robh+dt@kernel.org; Leizhen (ThunderTown) ; >> bhelgaas@google.com; dwmw2@infradead.org; liubo (CU) >> ; rjw@rjwysocki.net; robdclark@gmail.com; >> hanjun.guo@linaro.org; Sudeep Holla ; Robin >> Murphy ; nwatters@codeaurora.org; Linuxarm >> >> Subject: Re: [RFCv2 PATCH 14/36] iommu/arm-smmu-v3: Add support for >> Substream IDs >> >> Hi Shameer, >> >> On Thu, Nov 02, 2017 at 12:49:32PM +0000, Shameerali Kolothum Thodi wrote: >>> We had a go with this series on HiSIlicon D05 platform which doesn't have >>> support for ssids/ATS/PRI, to make sure it generally works. >>> >>> But observed the below crash on boot, >>> >>> [ 16.009084] WARNING: CPU: 59 PID: 391 at mm/page_alloc.c:3883 >> __alloc_pages_nodemask+0x19c/0xc48 >>> [ 16.026797] Modules linked in: >>> [ 16.032944] CPU: 59 PID: 391 Comm: kworker/59:1 Not tainted 4.14.0-rc1- >> 159539-ge42aca3 #236 >>> [...] >>> [ 16.068206] Workqueue: events deferred_probe_work_func >>> [ 16.078557] task: ffff8017d38a0000 task.stack: ffff00000b198000 >>> [ 16.090486] PC is at __alloc_pages_nodemask+0x19c/0xc48 >>> [ 16.101013] LR is at __alloc_pages_nodemask+0xe0/0xc48 >>> [ 16.469220] [] __alloc_pages_nodemask+0x19c/0xc48 >>> [ 16.481854] [] alloc_pages_current+0x80/0xcc >>> [ 16.493607] [] __get_free_pages+0xc/0x38 >>> [ 16.504661] [] swiotlb_alloc_coherent+0x64/0x190 >>> [ 16.517117] [] __dma_alloc+0x110/0x204 >>> [ 16.527820] [] dmam_alloc_coherent+0x88/0xf0 >>> [ 16.539575] [] >> arm_smmu_domain_finalise_s1+0x60/0x248 >>> [ 16.552909] [] arm_smmu_attach_dev+0x264/0x300 >>> [ 16.565013] [] __iommu_attach_device+0x48/0x5c >>> [ 16.577117] [] iommu_group_add_device+0x144/0x3a4 >>> [ 16.589746] [] iommu_group_get_for_dev+0x70/0xf8 >>> [ 16.602201] [] arm_smmu_add_device+0x1a4/0x418 >>> [ 16.614308] [] iort_iommu_configure+0xf0/0x16c >>> [ 16.626416] [] acpi_dma_configure+0x30/0x70 >>> [ 16.637994] [] dma_configure+0xa8/0xd4 >>> [ 16.648695] [] driver_probe_device+0x1a4/0x2dc >>> [ 16.673081] [] bus_for_each_drv+0x54/0x94 >>> [ 16.684307] [] __device_attach+0xc4/0x12c >>> [ 16.695533] [] device_initial_probe+0x10/0x18 >>> [ 16.707462] [] bus_probe_device+0x90/0x98 >>> >>> After a bit of debug it looks like on platforms where ssid is not supported, >>> s1_cfg.num_contexts is set to zero and it eventually results in this crash >>> in, >>> arm_smmu_domain_finalise_s1() -->arm_smmu_alloc_cd_tables()--> >>> arm_smmu_alloc_cd_leaf_table() as num_leaf_entries is zero. >>> >>> With the below fix, it works on D05 now, >>> >>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c >>> index 8ad90e2..51f5821 100644 >>> --- a/drivers/iommu/arm-smmu-v3.c >>> +++ b/drivers/iommu/arm-smmu-v3.c >>> @@ -2433,7 +2433,10 @@ static int arm_smmu_domain_finalise(struct >> iommu_domain *domain, >>> domain->min_pasid = 1; >>> domain->max_pasid = master->num_ssids - 1; >>> smmu_domain->s1_cfg.num_contexts = master->num_ssids; >>> + } else { >>> + smmu_domain->s1_cfg.num_contexts = 1; >>> } >>> + >>> smmu_domain->s1_cfg.can_stall = master->ste.can_stall; >>> break; >>> case ARM_SMMU_DOMAIN_NESTED: >>> >>> >>> I am not sure this is right place do this. Please take a look. >> >> Thanks for testing the series and reporting the bug. I added the >> following patch to branch svm/current, does it work for you? > > Yes, it does. > > Thanks, > Shameer > >> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c >> index 42c8378624ed..edda466adc81 100644 >> --- a/drivers/iommu/arm-smmu-v3.c >> +++ b/drivers/iommu/arm-smmu-v3.c >> @@ -3169,9 +3169,7 @@ static int arm_smmu_add_device(struct device *dev) >> } >> } >> >> - if (smmu->ssid_bits) >> - master->num_ssids = 1 << min(smmu->ssid_bits, >> - fwspec->num_pasid_bits); >> + master->num_ssids = 1 << min(smmu->ssid_bits, fwspec- >>> num_pasid_bits); If fwspec->num_pasid_bits = 0, then master have _one_ num_ssids ? It seems Shameerali's fix is better ? >> >> if (fwspec->can_stall && smmu->features & ARM_SMMU_FEAT_STALLS) { >> master->can_fault = true; > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Subject: Re: [RFCv2 PATCH 14/36] iommu/arm-smmu-v3: Add support for Substream IDs To: Shameerali Kolothum Thodi , Jean-Philippe Brucker References: <20171006133203.22803-1-jean-philippe.brucker@arm.com> <20171006133203.22803-15-jean-philippe.brucker@arm.com> <5FC3163CFD30C246ABAA99954A238FA838454887@FRAEML521-MBX.china.huawei.com> <20171102155152.GA11899@e106794-lin.localdomain> <5FC3163CFD30C246ABAA99954A238FA838454A9B@FRAEML521-MBX.china.huawei.com> From: Yisheng Xie Message-ID: <37a82eaa-dc9d-af98-6cb8-941ca925b838@huawei.com> Date: Fri, 3 Nov 2017 13:45:26 +0800 MIME-Version: 1.0 In-Reply-To: <5FC3163CFD30C246ABAA99954A238FA838454A9B@FRAEML521-MBX.china.huawei.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Gabriele Paoloni , "linux-pci@vger.kernel.org" , Will Deacon , Linuxarm , "okaya@codeaurora.org" , Lorenzo Pieralisi , "yi.l.liu@intel.com" , "ashok.raj@intel.com" , "tn@semihalf.com" , "joro@8bytes.org" , "robdclark@gmail.com" , "linux-acpi@vger.kernel.org" , Catalin Marinas , "rfranz@cavium.com" , "lenb@kernel.org" , "devicetree@vger.kernel.org" , "jacob.jun.pan@linux.intel.com" , "alex.williamson@redhat.com" , "robh+dt@kernel.org" , "Leizhen \(ThunderTown\)" , "bhelgaas@google.com" , "linux-arm-kernel@lists.infradead.org" , Robin Murphy , "liubo \(CU\)" , "rjw@rjwysocki.net" , "iommu@lists.linux-foundation.org" , "hanjun.guo@linaro.org" , Sudeep Holla , "dwmw2@infradead.org" , "nwatters@codeaurora.org" Content-Type: text/plain; charset="us-ascii" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+bjorn=helgaas.com@lists.infradead.org List-ID: Hi Jean, On 2017/11/3 1:02, Shameerali Kolothum Thodi wrote: > > >> -----Original Message----- >> From: Jean-Philippe Brucker [mailto:Jean-Philippe.Brucker@arm.com] >> Sent: Thursday, November 02, 2017 3:52 PM >> To: Shameerali Kolothum Thodi >> Cc: linux-arm-kernel@lists.infradead.org; linux-pci@vger.kernel.org; linux- >> acpi@vger.kernel.org; devicetree@vger.kernel.org; iommu@lists.linux- >> foundation.org; Mark Rutland ; xieyisheng (A) >> ; Gabriele Paoloni >> ; Catalin Marinas >> ; Will Deacon ; >> okaya@codeaurora.org; yi.l.liu@intel.com; Lorenzo Pieralisi >> ; ashok.raj@intel.com; tn@semihalf.com; >> joro@8bytes.org; rfranz@cavium.com; lenb@kernel.org; >> jacob.jun.pan@linux.intel.com; alex.williamson@redhat.com; >> robh+dt@kernel.org; Leizhen (ThunderTown) ; >> bhelgaas@google.com; dwmw2@infradead.org; liubo (CU) >> ; rjw@rjwysocki.net; robdclark@gmail.com; >> hanjun.guo@linaro.org; Sudeep Holla ; Robin >> Murphy ; nwatters@codeaurora.org; Linuxarm >> >> Subject: Re: [RFCv2 PATCH 14/36] iommu/arm-smmu-v3: Add support for >> Substream IDs >> >> Hi Shameer, >> >> On Thu, Nov 02, 2017 at 12:49:32PM +0000, Shameerali Kolothum Thodi wrote: >>> We had a go with this series on HiSIlicon D05 platform which doesn't have >>> support for ssids/ATS/PRI, to make sure it generally works. >>> >>> But observed the below crash on boot, >>> >>> [ 16.009084] WARNING: CPU: 59 PID: 391 at mm/page_alloc.c:3883 >> __alloc_pages_nodemask+0x19c/0xc48 >>> [ 16.026797] Modules linked in: >>> [ 16.032944] CPU: 59 PID: 391 Comm: kworker/59:1 Not tainted 4.14.0-rc1- >> 159539-ge42aca3 #236 >>> [...] >>> [ 16.068206] Workqueue: events deferred_probe_work_func >>> [ 16.078557] task: ffff8017d38a0000 task.stack: ffff00000b198000 >>> [ 16.090486] PC is at __alloc_pages_nodemask+0x19c/0xc48 >>> [ 16.101013] LR is at __alloc_pages_nodemask+0xe0/0xc48 >>> [ 16.469220] [] __alloc_pages_nodemask+0x19c/0xc48 >>> [ 16.481854] [] alloc_pages_current+0x80/0xcc >>> [ 16.493607] [] __get_free_pages+0xc/0x38 >>> [ 16.504661] [] swiotlb_alloc_coherent+0x64/0x190 >>> [ 16.517117] [] __dma_alloc+0x110/0x204 >>> [ 16.527820] [] dmam_alloc_coherent+0x88/0xf0 >>> [ 16.539575] [] >> arm_smmu_domain_finalise_s1+0x60/0x248 >>> [ 16.552909] [] arm_smmu_attach_dev+0x264/0x300 >>> [ 16.565013] [] __iommu_attach_device+0x48/0x5c >>> [ 16.577117] [] iommu_group_add_device+0x144/0x3a4 >>> [ 16.589746] [] iommu_group_get_for_dev+0x70/0xf8 >>> [ 16.602201] [] arm_smmu_add_device+0x1a4/0x418 >>> [ 16.614308] [] iort_iommu_configure+0xf0/0x16c >>> [ 16.626416] [] acpi_dma_configure+0x30/0x70 >>> [ 16.637994] [] dma_configure+0xa8/0xd4 >>> [ 16.648695] [] driver_probe_device+0x1a4/0x2dc >>> [ 16.673081] [] bus_for_each_drv+0x54/0x94 >>> [ 16.684307] [] __device_attach+0xc4/0x12c >>> [ 16.695533] [] device_initial_probe+0x10/0x18 >>> [ 16.707462] [] bus_probe_device+0x90/0x98 >>> >>> After a bit of debug it looks like on platforms where ssid is not supported, >>> s1_cfg.num_contexts is set to zero and it eventually results in this crash >>> in, >>> arm_smmu_domain_finalise_s1() -->arm_smmu_alloc_cd_tables()--> >>> arm_smmu_alloc_cd_leaf_table() as num_leaf_entries is zero. >>> >>> With the below fix, it works on D05 now, >>> >>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c >>> index 8ad90e2..51f5821 100644 >>> --- a/drivers/iommu/arm-smmu-v3.c >>> +++ b/drivers/iommu/arm-smmu-v3.c >>> @@ -2433,7 +2433,10 @@ static int arm_smmu_domain_finalise(struct >> iommu_domain *domain, >>> domain->min_pasid = 1; >>> domain->max_pasid = master->num_ssids - 1; >>> smmu_domain->s1_cfg.num_contexts = master->num_ssids; >>> + } else { >>> + smmu_domain->s1_cfg.num_contexts = 1; >>> } >>> + >>> smmu_domain->s1_cfg.can_stall = master->ste.can_stall; >>> break; >>> case ARM_SMMU_DOMAIN_NESTED: >>> >>> >>> I am not sure this is right place do this. Please take a look. >> >> Thanks for testing the series and reporting the bug. I added the >> following patch to branch svm/current, does it work for you? > > Yes, it does. > > Thanks, > Shameer > >> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c >> index 42c8378624ed..edda466adc81 100644 >> --- a/drivers/iommu/arm-smmu-v3.c >> +++ b/drivers/iommu/arm-smmu-v3.c >> @@ -3169,9 +3169,7 @@ static int arm_smmu_add_device(struct device *dev) >> } >> } >> >> - if (smmu->ssid_bits) >> - master->num_ssids = 1 << min(smmu->ssid_bits, >> - fwspec->num_pasid_bits); >> + master->num_ssids = 1 << min(smmu->ssid_bits, fwspec- >>> num_pasid_bits); If fwspec->num_pasid_bits = 0, then master have _one_ num_ssids ? It seems Shameerali's fix is better ? >> >> if (fwspec->can_stall && smmu->features & ARM_SMMU_FEAT_STALLS) { >> master->can_fault = true; > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel From mboxrd@z Thu Jan 1 00:00:00 1970 From: xieyisheng1@huawei.com (Yisheng Xie) Date: Fri, 3 Nov 2017 13:45:26 +0800 Subject: [RFCv2 PATCH 14/36] iommu/arm-smmu-v3: Add support for Substream IDs In-Reply-To: <5FC3163CFD30C246ABAA99954A238FA838454A9B@FRAEML521-MBX.china.huawei.com> References: <20171006133203.22803-1-jean-philippe.brucker@arm.com> <20171006133203.22803-15-jean-philippe.brucker@arm.com> <5FC3163CFD30C246ABAA99954A238FA838454887@FRAEML521-MBX.china.huawei.com> <20171102155152.GA11899@e106794-lin.localdomain> <5FC3163CFD30C246ABAA99954A238FA838454A9B@FRAEML521-MBX.china.huawei.com> Message-ID: <37a82eaa-dc9d-af98-6cb8-941ca925b838@huawei.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Jean, On 2017/11/3 1:02, Shameerali Kolothum Thodi wrote: > > >> -----Original Message----- >> From: Jean-Philippe Brucker [mailto:Jean-Philippe.Brucker at arm.com] >> Sent: Thursday, November 02, 2017 3:52 PM >> To: Shameerali Kolothum Thodi >> Cc: linux-arm-kernel at lists.infradead.org; linux-pci at vger.kernel.org; linux- >> acpi at vger.kernel.org; devicetree at vger.kernel.org; iommu at lists.linux- >> foundation.org; Mark Rutland ; xieyisheng (A) >> ; Gabriele Paoloni >> ; Catalin Marinas >> ; Will Deacon ; >> okaya at codeaurora.org; yi.l.liu at intel.com; Lorenzo Pieralisi >> ; ashok.raj at intel.com; tn at semihalf.com; >> joro at 8bytes.org; rfranz at cavium.com; lenb at kernel.org; >> jacob.jun.pan at linux.intel.com; alex.williamson at redhat.com; >> robh+dt at kernel.org; Leizhen (ThunderTown) ; >> bhelgaas at google.com; dwmw2 at infradead.org; liubo (CU) >> ; rjw at rjwysocki.net; robdclark at gmail.com; >> hanjun.guo at linaro.org; Sudeep Holla ; Robin >> Murphy ; nwatters at codeaurora.org; Linuxarm >> >> Subject: Re: [RFCv2 PATCH 14/36] iommu/arm-smmu-v3: Add support for >> Substream IDs >> >> Hi Shameer, >> >> On Thu, Nov 02, 2017 at 12:49:32PM +0000, Shameerali Kolothum Thodi wrote: >>> We had a go with this series on HiSIlicon D05 platform which doesn't have >>> support for ssids/ATS/PRI, to make sure it generally works. >>> >>> But observed the below crash on boot, >>> >>> [ 16.009084] WARNING: CPU: 59 PID: 391 at mm/page_alloc.c:3883 >> __alloc_pages_nodemask+0x19c/0xc48 >>> [ 16.026797] Modules linked in: >>> [ 16.032944] CPU: 59 PID: 391 Comm: kworker/59:1 Not tainted 4.14.0-rc1- >> 159539-ge42aca3 #236 >>> [...] >>> [ 16.068206] Workqueue: events deferred_probe_work_func >>> [ 16.078557] task: ffff8017d38a0000 task.stack: ffff00000b198000 >>> [ 16.090486] PC is at __alloc_pages_nodemask+0x19c/0xc48 >>> [ 16.101013] LR is at __alloc_pages_nodemask+0xe0/0xc48 >>> [ 16.469220] [] __alloc_pages_nodemask+0x19c/0xc48 >>> [ 16.481854] [] alloc_pages_current+0x80/0xcc >>> [ 16.493607] [] __get_free_pages+0xc/0x38 >>> [ 16.504661] [] swiotlb_alloc_coherent+0x64/0x190 >>> [ 16.517117] [] __dma_alloc+0x110/0x204 >>> [ 16.527820] [] dmam_alloc_coherent+0x88/0xf0 >>> [ 16.539575] [] >> arm_smmu_domain_finalise_s1+0x60/0x248 >>> [ 16.552909] [] arm_smmu_attach_dev+0x264/0x300 >>> [ 16.565013] [] __iommu_attach_device+0x48/0x5c >>> [ 16.577117] [] iommu_group_add_device+0x144/0x3a4 >>> [ 16.589746] [] iommu_group_get_for_dev+0x70/0xf8 >>> [ 16.602201] [] arm_smmu_add_device+0x1a4/0x418 >>> [ 16.614308] [] iort_iommu_configure+0xf0/0x16c >>> [ 16.626416] [] acpi_dma_configure+0x30/0x70 >>> [ 16.637994] [] dma_configure+0xa8/0xd4 >>> [ 16.648695] [] driver_probe_device+0x1a4/0x2dc >>> [ 16.673081] [] bus_for_each_drv+0x54/0x94 >>> [ 16.684307] [] __device_attach+0xc4/0x12c >>> [ 16.695533] [] device_initial_probe+0x10/0x18 >>> [ 16.707462] [] bus_probe_device+0x90/0x98 >>> >>> After a bit of debug it looks like on platforms where ssid is not supported, >>> s1_cfg.num_contexts is set to zero and it eventually results in this crash >>> in, >>> arm_smmu_domain_finalise_s1() -->arm_smmu_alloc_cd_tables()--> >>> arm_smmu_alloc_cd_leaf_table() as num_leaf_entries is zero. >>> >>> With the below fix, it works on D05 now, >>> >>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c >>> index 8ad90e2..51f5821 100644 >>> --- a/drivers/iommu/arm-smmu-v3.c >>> +++ b/drivers/iommu/arm-smmu-v3.c >>> @@ -2433,7 +2433,10 @@ static int arm_smmu_domain_finalise(struct >> iommu_domain *domain, >>> domain->min_pasid = 1; >>> domain->max_pasid = master->num_ssids - 1; >>> smmu_domain->s1_cfg.num_contexts = master->num_ssids; >>> + } else { >>> + smmu_domain->s1_cfg.num_contexts = 1; >>> } >>> + >>> smmu_domain->s1_cfg.can_stall = master->ste.can_stall; >>> break; >>> case ARM_SMMU_DOMAIN_NESTED: >>> >>> >>> I am not sure this is right place do this. Please take a look. >> >> Thanks for testing the series and reporting the bug. I added the >> following patch to branch svm/current, does it work for you? > > Yes, it does. > > Thanks, > Shameer > >> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c >> index 42c8378624ed..edda466adc81 100644 >> --- a/drivers/iommu/arm-smmu-v3.c >> +++ b/drivers/iommu/arm-smmu-v3.c >> @@ -3169,9 +3169,7 @@ static int arm_smmu_add_device(struct device *dev) >> } >> } >> >> - if (smmu->ssid_bits) >> - master->num_ssids = 1 << min(smmu->ssid_bits, >> - fwspec->num_pasid_bits); >> + master->num_ssids = 1 << min(smmu->ssid_bits, fwspec- >>> num_pasid_bits); If fwspec->num_pasid_bits = 0, then master have _one_ num_ssids ? It seems Shameerali's fix is better ? >> >> if (fwspec->can_stall && smmu->features & ARM_SMMU_FEAT_STALLS) { >> master->can_fault = true; >