Re: [PATCH v4 3/7] iommu: Support allocation of global PASIDs outside SVA

Baolu Lu
2023-04-10T01:34:24Z

On 4/8/23 2:05 AM, Jacob Pan wrote:
> Devices that use Intel ENQCMD to submit work must use global PASIDs in
> that the PASID are stored in a per CPU MSR. When such device need to
> submit work for in-kernel DMA with PASID, it must allocate PASIDs from
> the same global number space to avoid conflict.
>
> This patch moves global PASID allocation APIs from SVA to IOMMU APIs.
> It is expected that device drivers will use the allocated PASIDs to attach
> to appropriate IOMMU domains for use.
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> v4: move dummy functions outside ifdef CONFIG_IOMMU_SVA (Baolu)
> ---
> drivers/iommu/iommu-sva.c | 10 ++++------
> drivers/iommu/iommu.c | 33 +++++++++++++++++++++++++++++++++
> include/linux/iommu.h | 11 +++++++++++
> 3 files changed, 48 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
> index c434b95dc8eb..222544587582 100644
> --- a/drivers/iommu/iommu-sva.c
> +++ b/drivers/iommu/iommu-sva.c
> @@ -9,15 +9,13 @@
> #include "iommu-sva.h"
>
> static DEFINE_MUTEX(iommu_sva_lock);
> -static DEFINE_IDA(iommu_global_pasid_ida);
>
> /* Allocate a PASID for the mm within range (inclusive) */
> static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
> {
> int ret = 0;
>
> - if (!pasid_valid(min) || !pasid_valid(max) ||
> - min == 0 || max < min)
> + if (!pasid_valid(min) || !pasid_valid(max) || max < min)
> return -EINVAL;
>
> mutex_lock(&iommu_sva_lock);
> @@ -28,8 +26,8 @@ static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t ma
> goto out;
> }
>
> - ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_KERNEL);
> - if (ret < min)
> + ret = iommu_alloc_global_pasid(min, max);
> + if (!pasid_valid(ret))
> goto out;
> mm->pasid = ret;
> ret = 0;
> @@ -211,5 +209,5 @@ void mm_pasid_drop(struct mm_struct *mm)
> if (likely(!pasid_valid(mm->pasid)))
> return;
>
> - ida_free(&iommu_global_pasid_ida, mm->pasid);
> + iommu_free_global_pasid(mm->pasid);
> }
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 10db680acaed..2a132ff7e3de 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -38,6 +38,7 @@
>
> static struct kset *iommu_group_kset;
> static DEFINE_IDA(iommu_group_ida);
> +static DEFINE_IDA(iommu_global_pasid_ida);
>
> static unsigned int iommu_def_domain_type __read_mostly;
> static bool iommu_dma_strict __read_mostly = IS_ENABLED(CONFIG_IOMMU_DEFAULT_DMA_STRICT);
> @@ -3450,3 +3451,35 @@ struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
>
> return domain;
> }
> +
> +/**
> + * @brief
> + * Allocate a PASID from the global number space.
> + *
> + * @param min starting range, inclusive
> + * @param max ending range, inclusive
> + * @return The reserved PASID on success or IOMMU_PASID_INVALID on failure.
> + */
> +ioasid_t iommu_alloc_global_pasid(ioasid_t min, ioasid_t max)
> +{
> + int ret;
> +
> + if (!pasid_valid(min) || !pasid_valid(max) || max < min)
> + return IOMMU_PASID_INVALID;
> +
> + ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_KERNEL);
> + if (ret < 0)
> + return IOMMU_PASID_INVALID;
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(iommu_alloc_global_pasid);
> +
> +void iommu_free_global_pasid(ioasid_t pasid)
> +{
> + if (WARN_ON(!pasid_valid(pasid)))
> + return;
> +
> + ida_free(&iommu_global_pasid_ida, pasid);
> +}
> +EXPORT_SYMBOL_GPL(iommu_free_global_pasid);
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 54f535ff9868..c9720ddc81d2 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -723,6 +723,8 @@ void iommu_detach_device_pasid(struct iommu_domain *domain,
> struct iommu_domain *
> iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid,
> unsigned int type);
> +ioasid_t iommu_alloc_global_pasid(ioasid_t min, ioasid_t max);
> +void iommu_free_global_pasid(ioasid_t pasid);
> #else /* CONFIG_IOMMU_API */
>
> struct iommu_ops {};
> @@ -1089,6 +1091,13 @@ iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid,
> {
> return NULL;
> }
> +
> +static inline ioasid_t iommu_alloc_global_pasid(ioasid_t min, ioasid_t max)
> +{
> + return IOMMU_PASID_INVALID;
> +}
> +
> +static inline void iommu_free_global_pasid(ioasid_t pasid) {}
> #endif /* CONFIG_IOMMU_API */
>
> /**
> @@ -1187,6 +1196,7 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev,
> struct mm_struct *mm);
> void iommu_sva_unbind_device(struct iommu_sva *handle);
> u32 iommu_sva_get_pasid(struct iommu_sva *handle);
> +

Nit: irrelevant blank line

> #else
> static inline struct iommu_sva *
> iommu_sva_bind_device(struct device *dev, struct mm_struct *mm)
> @@ -1202,6 +1212,7 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
> {
> return IOMMU_PASID_INVALID;
> }
> +

Ditto

> static inline void mm_pasid_init(struct mm_struct *mm) {}
> static inline void mm_pasid_drop(struct mm_struct *mm) {}
> #endif /* CONFIG_IOMMU_SVA */

Other look good to me.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu