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[34.126.98.232]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-23f75d13bdfsm77086475ad.51.2025.07.23.06.37.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Jul 2025 06:37:58 -0700 (PDT) Date: Wed, 23 Jul 2025 13:37:53 +0000 From: Pranjal Shrivastava To: Nicolin Chen Cc: jgg@nvidia.com, will@kernel.org, joro@8bytes.org, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org Subject: Re: [PATCH v3 2/2] iommu/arm-smmu-v3: Replace vsmmu_size/type with get_viommu_size Message-ID: References: <20250721200444.1740461-1-nicolinc@nvidia.com> <20250721200444.1740461-3-nicolinc@nvidia.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250721200444.1740461-3-nicolinc@nvidia.com> On Mon, Jul 21, 2025 at 01:04:44PM -0700, Nicolin Chen wrote: > It's more flexible to have a get_viommu_size op. Replace static vsmmu_size > and vsmmu_type with that. > > Suggested-by: Will Deacon > Acked-by: Will Deacon > Signed-off-by: Nicolin Chen > --- > .../iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 8 ++------ > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 4 ++-- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 3 +-- > drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c | 14 ++++++++++++-- > 4 files changed, 17 insertions(+), 12 deletions(-) > > 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 c034d6c5468f..8cd8929bbfdf 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 > @@ -423,10 +423,9 @@ size_t arm_smmu_get_viommu_size(struct device *dev, > if (viommu_type == IOMMU_VIOMMU_TYPE_ARM_SMMUV3) > return VIOMMU_STRUCT_SIZE(struct arm_vsmmu, core); > > - if (!smmu->impl_ops || !smmu->impl_ops->vsmmu_size || > - viommu_type != smmu->impl_ops->vsmmu_type) > + if (!smmu->impl_ops || !smmu->impl_ops->get_viommu_size) > return 0; > - return smmu->impl_ops->vsmmu_size; > + return smmu->impl_ops->get_viommu_size(viommu_type); > } > > int arm_vsmmu_init(struct iommufd_viommu *viommu, > @@ -451,9 +450,6 @@ int arm_vsmmu_init(struct iommufd_viommu *viommu, > return 0; > } > > - /* Unsupported type was rejected in arm_smmu_get_viommu_size() */ > - if (WARN_ON(viommu->type != smmu->impl_ops->vsmmu_type)) > - return -EOPNOTSUPP; > return smmu->impl_ops->vsmmu_init(vsmmu, user_data); > } > > 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 9f4ad3705801..f56113107c8a 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > @@ -4716,8 +4716,8 @@ static struct arm_smmu_device *arm_smmu_impl_probe(struct arm_smmu_device *smmu) > > ops = new_smmu->impl_ops; > if (ops) { > - /* vsmmu_size and vsmmu_init ops must be paired */ > - if (WARN_ON(!ops->vsmmu_size != !ops->vsmmu_init)) { > + /* get_viommu_size and vsmmu_init ops must be paired */ > + if (WARN_ON(!ops->get_viommu_size != !ops->vsmmu_init)) { > ret = -EINVAL; > goto err_remove; > } > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h > index 3fa02c51df9f..e332f5ba2f8a 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h > @@ -728,8 +728,7 @@ struct arm_smmu_impl_ops { > */ > void *(*hw_info)(struct arm_smmu_device *smmu, u32 *length, > enum iommu_hw_info_type *type); > - const size_t vsmmu_size; > - const enum iommu_viommu_type vsmmu_type; > + size_t (*get_viommu_size)(enum iommu_viommu_type viommu_type); > int (*vsmmu_init)(struct arm_vsmmu *vsmmu, > const struct iommu_user_data *user_data); > }; > diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c > index 4c86eacd36b1..46005ed52bc2 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c > +++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c > @@ -832,6 +832,13 @@ static void *tegra241_cmdqv_hw_info(struct arm_smmu_device *smmu, u32 *length, > return info; > } > > +static size_t tegra241_cmdqv_get_vintf_size(enum iommu_viommu_type viommu_type) > +{ > + if (viommu_type != IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV) > + return 0; > + return VIOMMU_STRUCT_SIZE(struct tegra241_vintf, vsmmu.core); > +} > + > static struct arm_smmu_impl_ops tegra241_cmdqv_impl_ops = { > /* For in-kernel use */ > .get_secondary_cmdq = tegra241_cmdqv_get_cmdq, > @@ -839,8 +846,7 @@ static struct arm_smmu_impl_ops tegra241_cmdqv_impl_ops = { > .device_remove = tegra241_cmdqv_remove, > /* For user-space use */ > .hw_info = tegra241_cmdqv_hw_info, > - .vsmmu_size = VIOMMU_STRUCT_SIZE(struct tegra241_vintf, vsmmu.core), > - .vsmmu_type = IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV, > + .get_viommu_size = tegra241_cmdqv_get_vintf_size, > .vsmmu_init = tegra241_cmdqv_init_vintf_user, > }; > > @@ -1273,6 +1279,10 @@ tegra241_cmdqv_init_vintf_user(struct arm_vsmmu *vsmmu, > phys_addr_t page0_base; > int ret; > > + /* Unsupported type was rejected in tegra241_cmdqv_get_vintf_size() */ > + if (WARN_ON(vsmmu->core.type != IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV)) > + return -EOPNOTSUPP; > + Nit: I don't think we'd expect a call to this if the vintf_size returned 0? I see that in iommufd_viommu_alloc_ioctl, we already have a check: viommu_size = ops->get_viommu_size(idev->dev, cmd->type); if (!viommu_size) { rc = -EOPNOTSUPP; goto out_put_idev; } And call ops->viommu_init only when the above isn't met. Thus, if we still end up calling ops->viommu_init, shouldn't we BUG_ON() it? I'd rather have the core code handle such things (since the driver is simply implementing the ops) and BUG_ON() something that's terribly wrong.. I can't see any ops->viommu_init being called elsewhere atm, let me know if there's a different path that I missed.. Apart from the above nit, Reviewed-by: Pranjal Shrivastava > if (!user_data) > return -EINVAL; > > -- > 2.43.0 > >