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[35.198.224.169]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2fe6a43cb81sm101015a91.38.2025.02.24.12.36.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Feb 2025 12:36:06 -0800 (PST) Date: Mon, 24 Feb 2025 20:35:56 +0000 From: Pranjal Shrivastava To: Nicolin Chen Cc: jgg@nvidia.com, kevin.tian@intel.com, corbet@lwn.net, will@kernel.org, joro@8bytes.org, suravee.suthikulpanit@amd.com, robin.murphy@arm.com, dwmw2@infradead.org, baolu.lu@linux.intel.com, shuah@kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, eric.auger@redhat.com, jean-philippe@linaro.org, mdf@kernel.org, mshavit@google.com, shameerali.kolothum.thodi@huawei.com, smostafa@google.com, ddutile@redhat.com, yi.l.liu@intel.com, patches@lists.linux.dev Subject: Re: [PATCH v7 12/14] iommu/arm-smmu-v3: Introduce struct arm_smmu_vmaster Message-ID: References: Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: oN sAt, Feb 22, 2025 at 07:54:09AM -0800, Nicolin Chen wrote: > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c > index 5aa2e7af58b4..364d8469a480 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c > @@ -85,6 +85,59 @@ static void arm_smmu_make_nested_domain_ste( > } > } > > +int arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state, > + struct iommu_domain *domain) > +{ > + struct arm_smmu_nested_domain *nested_domain; > + struct arm_smmu_vmaster *vmaster; > + unsigned long vsid; > + int ret; > + > + iommu_group_mutex_assert(state->master->dev); > + > + if (domain->type != IOMMU_DOMAIN_NESTED) > + return 0; > + nested_domain = to_smmu_nested_domain(domain); > + > + /* Skip invalid vSTE */ > + if (!(nested_domain->ste[0] & cpu_to_le64(STRTAB_STE_0_V))) > + return 0; > + > + ret = iommufd_viommu_get_vdev_id(&nested_domain->vsmmu->core, > + state->master->dev, &vsid); > + if (ret) > + return ret; > + > + vmaster = kzalloc(sizeof(*vmaster), GFP_KERNEL); > + if (!vmaster) > + return -ENOMEM; > + vmaster->vsmmu = nested_domain->vsmmu; > + vmaster->vsid = vsid; > + state->vmaster = vmaster; > + > + return 0; > +} > + > +void arm_smmu_attach_commit_vmaster(struct arm_smmu_attach_state *state) > +{ > + struct arm_smmu_master *master = state->master; > + > + mutex_lock(&master->smmu->streams_mutex); > + if (state->vmaster != master->vmaster) { > + kfree(master->vmaster); > + master->vmaster = state->vmaster; > + } Does this condition suggest that we might end up calling `arm_smmu_attach_prepare_vmaster()` multiple times before __actually__ commiting to a vmaster? > + mutex_unlock(&master->smmu->streams_mutex); > +} > + > +void arm_smmu_master_clear_vmaster(struct arm_smmu_master *master) > +{ > + mutex_lock(&master->smmu->streams_mutex); > + kfree(master->vmaster); > + master->vmaster = NULL; > + mutex_unlock(&master->smmu->streams_mutex); > +} > + > static int arm_smmu_attach_dev_nested(struct iommu_domain *domain, > struct device *dev) > { > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > index 358072b4e293..9e50bcee69d1 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > @@ -2803,6 +2803,7 @@ int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state, > struct arm_smmu_domain *smmu_domain = > to_smmu_domain_devices(new_domain); > unsigned long flags; > + int ret; > > /* > * arm_smmu_share_asid() must not see two domains pointing to the same > @@ -2832,9 +2833,15 @@ int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state, > } > > if (smmu_domain) { > + ret = arm_smmu_attach_prepare_vmaster(state, new_domain); IMO, this adds a little confusion for folks not using iommufd. I guess it'd be cleaner if we invoke this below within the: `if (new_domain->type == IOMMU_DOMAIN_NESTED)` condition instead of simply returning from the function if the new_domain->type isn't NESTED. > + if (ret) > + return ret; > + > master_domain = kzalloc(sizeof(*master_domain), GFP_KERNEL); > - if (!master_domain) > + if (!master_domain) { > + kfree(state->vmaster); > return -ENOMEM; > + } > master_domain->master = master; > master_domain->ssid = state->ssid; > if (new_domain->type == IOMMU_DOMAIN_NESTED) > @@ -2861,6 +2868,7 @@ int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state, > spin_unlock_irqrestore(&smmu_domain->devices_lock, > flags); > kfree(master_domain); > + kfree(state->vmaster); > return -EINVAL; > } > > @@ -2893,6 +2901,8 @@ void arm_smmu_attach_commit(struct arm_smmu_attach_state *state) > > lockdep_assert_held(&arm_smmu_asid_lock); > > + arm_smmu_attach_commit_vmaster(state); > + > if (state->ats_enabled && !master->ats_enabled) { > arm_smmu_enable_ats(master); > } else if (state->ats_enabled && master->ats_enabled) { > @@ -3162,6 +3172,7 @@ static int arm_smmu_attach_dev_identity(struct iommu_domain *domain, > struct arm_smmu_ste ste; > struct arm_smmu_master *master = dev_iommu_priv_get(dev); > > + arm_smmu_master_clear_vmaster(master); > arm_smmu_make_bypass_ste(master->smmu, &ste); > arm_smmu_attach_dev_ste(domain, dev, &ste, STRTAB_STE_1_S1DSS_BYPASS); > return 0; > @@ -3180,7 +3191,9 @@ static int arm_smmu_attach_dev_blocked(struct iommu_domain *domain, > struct device *dev) > { > struct arm_smmu_ste ste; > + struct arm_smmu_master *master = dev_iommu_priv_get(dev); > > + arm_smmu_master_clear_vmaster(master); > arm_smmu_make_abort_ste(&ste); > arm_smmu_attach_dev_ste(domain, dev, &ste, > STRTAB_STE_1_S1DSS_TERMINATE); > Thanks, Praan