Re: [PATCH v2 14/19] iommu: Add guest PASID bind function

Auger Eric
2019-04-26T15:55:59Z

Hi Jacob,

On 4/24/19 1:31 AM, Jacob Pan wrote:
> Guest shared virtual address (SVA) may require host to shadow guest
> PASID tables. Guest PASID can also be allocated from the host via
> enlightened interfaces. In this case, guest needs to bind the guest
> mm, i.e. cr3 in guest phisical address to the actual PASID table in
physical
> the host IOMMU. Nesting will be turned on such that guest virtual
> address can go through a two level translation:
> - 1st level translates GVA to GPA
> - 2nd level translates GPA to HPA
> This patch introduces APIs to bind guest PASID data to the assigned
> device entry in the physical IOMMU. See the diagram below for usage
> explaination.
>
> .-------------. .---------------------------.
> | vIOMMU | | Guest process mm, FL only |
> | | '---------------------------'
> .----------------/
> | PASID Entry |--- PASID cache flush -
> '-------------' |
> | | V
> | |
> '-------------'
> Guest
> ------| Shadow |--------------------------|------------
> v v v
> Host
> .-------------. .----------------------.
> | pIOMMU | | Bind FL for GVA-GPA |
> | | '----------------------'
> .----------------/ |
> | PASID Entry | V (Nested xlate)
> '----------------\.---------------------.
> | | |Set SL to GPA-HPA |
> | | '---------------------'
> '-------------'
>
> Where:
> - FL = First level/stage one page tables
> - SL = Second level/stage two page tables
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> ---
> drivers/iommu/iommu.c | 20 ++++++++++++++++++++
> include/linux/iommu.h | 10 ++++++++++
> include/uapi/linux/iommu.h | 15 ++++++++++++++-
> 3 files changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 498c28a..072f8f3 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1561,6 +1561,26 @@ int iommu_cache_invalidate(struct iommu_domain *domain, struct device *dev,
> }
> EXPORT_SYMBOL_GPL(iommu_cache_invalidate);
>
> +int iommu_sva_bind_gpasid(struct iommu_domain *domain,
> + struct device *dev, struct gpasid_bind_data *data)
> +{
> + if (unlikely(!domain->ops->sva_bind_gpasid))
> + return -ENODEV;
> +
> + return domain->ops->sva_bind_gpasid(domain, dev, data);
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_bind_gpasid);
> +
> +int iommu_sva_unbind_gpasid(struct iommu_domain *domain, struct device *dev,
> + int pasid)
> +{
> + if (unlikely(!domain->ops->sva_unbind_gpasid))
> + return -ENODEV;
> +
> + return domain->ops->sva_unbind_gpasid(dev, pasid);
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_unbind_gpasid);
> +
> static void __iommu_detach_device(struct iommu_domain *domain,
> struct device *dev)
> {
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 4b92e4b..611388e 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -231,6 +231,8 @@ struct iommu_sva_ops {
> * @detach_pasid_table: detach the pasid table
> * @cache_invalidate: invalidate translation caches
> * @pgsize_bitmap: bitmap of all possible supported page sizes
> + * @sva_bind_gpasid: bind guest pasid and mm
> + * @sva_unbind_gpasid: unbind guest pasid and mm
> */
> struct iommu_ops {
> bool (*capable)(enum iommu_cap);
> @@ -295,6 +297,10 @@ struct iommu_ops {
>
> int (*cache_invalidate)(struct iommu_domain *domain, struct device *dev,
> struct iommu_cache_invalidate_info *inv_info);
> + int (*sva_bind_gpasid)(struct iommu_domain *domain,
> + struct device *dev, struct gpasid_bind_data *data);
> +
> + int (*sva_unbind_gpasid)(struct device *dev, int pasid);
So I am confused now. As the scalable mode PASID table entry contains
both the FL and SL PT pointers, will you ever use the
attach/detach_pasid_table or are we the only known users on ARM?

>
> unsigned long pgsize_bitmap;
> };
> @@ -409,6 +415,10 @@ extern void iommu_detach_pasid_table(struct iommu_domain *domain);
> extern int iommu_cache_invalidate(struct iommu_domain *domain,
> struct device *dev,
> struct iommu_cache_invalidate_info *inv_info);
> +extern int iommu_sva_bind_gpasid(struct iommu_domain *domain,
> + struct device *dev, struct gpasid_bind_data *data);
> +extern int iommu_sva_unbind_gpasid(struct iommu_domain *domain,
> + struct device *dev, int pasid);
definition in !CONFIG_IOMMU_API case?
> extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
> extern struct iommu_domain *iommu_get_dma_domain(struct device *dev);
> extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index 61a3fb7..5c95905 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -235,6 +235,19 @@ struct iommu_cache_invalidate_info {
> struct iommu_inv_addr_info addr_info;
> };
> };
> -
> +/**
> + * struct gpasid_bind_data - Information about device and guest PASID binding
> + * @gcr3: Guest CR3 value from guest mm
> + * @pasid: Process address space ID used for the guest mm
> + * @addr_width: Guest address width. Paging mode can also be derived.
> + */
> +struct gpasid_bind_data {
> + __u64 gcr3;
> + __u32 pasid;
> + __u32 addr_width;
> + __u32 flags;
> +#define IOMMU_SVA_GPASID_SRE BIT(0) /* supervisor request */
> + __u8 padding[4];
> +};

Thanks

Eric
>
> #endif /* _UAPI_IOMMU_H */