Re: [PATCH v2 01/16] iommu: introduce bind_pasid_table API function

[Jacob Pan <jacob.jun.pan@linux.intel.com>]

On Tue, 10 Oct 2017 17:45:53 +0100
Jean-Philippe Brucker <jean-philippe.brucker@arm.com> wrote:

> On 06/10/17 00:03, Jacob Pan wrote:
> > Virtual IOMMU was proposed to support Shared Virtual Memory (SVM)
> > use in the guest:
> > https://lists.gnu.org/archive/html/qemu-devel/2016-11/msg05311.html
> > 
> > As part of the proposed architecture, when an SVM capable PCI
> > device is assigned to a guest, nested mode is turned on. Guest owns
> > the first level page tables (request with PASID) which performs
> > GVA->GPA translation. Second level page tables are owned by the
> > host for GPA->HPA translation for both request with and without
> > PASID.
> > 
> > A new IOMMU driver interface is therefore needed to perform tasks as
> > follows:
> > * Enable nested translation and appropriate translation type
> > * Assign guest PASID table pointer (in GPA) and size to host IOMMU
> > 
> > This patch introduces new API functions to perform bind/unbind
> > guest PASID tables. Based on common data, model specific IOMMU
> > drivers can be extended to perform the specific steps for binding
> > pasid table of assigned devices.
> > 
> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
> > Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> > ---
> >  drivers/iommu/iommu.c      | 19 ++++++++++++++++
> >  include/linux/iommu.h      | 25 +++++++++++++++++++++
> >  include/uapi/linux/iommu.h | 55
> > ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 99
> > insertions(+) create mode 100644 include/uapi/linux/iommu.h
> > 
> > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > index 3de5c0b..761cf50 100644
> > --- a/drivers/iommu/iommu.c
> > +++ b/drivers/iommu/iommu.c
> > @@ -1322,6 +1322,25 @@ int iommu_attach_device(struct iommu_domain
> > *domain, struct device *dev) }
> >  EXPORT_SYMBOL_GPL(iommu_attach_device);
> >  
> > +int iommu_bind_pasid_table(struct iommu_domain *domain, struct
> > device *dev,
> > +			struct pasid_table_config *pasidt_binfo)
> > +{
> > +	if (unlikely(!domain->ops->bind_pasid_table))
> > +		return -ENODEV;
> > +
> > +	return domain->ops->bind_pasid_table(domain, dev,
> > pasidt_binfo); +}
> > +EXPORT_SYMBOL_GPL(iommu_bind_pasid_table);
> > +
> > +int iommu_unbind_pasid_table(struct iommu_domain *domain, struct
> > device *dev) +{
> > +	if (unlikely(!domain->ops->unbind_pasid_table))
> > +		return -EINVAL;
> > +
> > +	return domain->ops->unbind_pasid_table(domain, dev);
> > +}
> > +EXPORT_SYMBOL_GPL(iommu_unbind_pasid_table);
> > +
> >  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 41b8c57..672cc06 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -25,6 +25,7 @@
> >  #include <linux/errno.h>
> >  #include <linux/err.h>
> >  #include <linux/of.h>
> > +#include <uapi/linux/iommu.h>
> >  
> >  #define IOMMU_READ	(1 << 0)
> >  #define IOMMU_WRITE	(1 << 1)
> > @@ -187,6 +188,8 @@ struct iommu_resv_region {
> >   * @domain_get_windows: Return the number of windows for a domain
> >   * @of_xlate: add OF master IDs to iommu grouping
> >   * @pgsize_bitmap: bitmap of all possible supported page sizes
> > + * @bind_pasid_table: bind pasid table pointer for guest SVM
> > + * @unbind_pasid_table: unbind pasid table pointer and restore
> > defaults */
> >  struct iommu_ops {
> >  	bool (*capable)(enum iommu_cap);
> > @@ -233,8 +236,14 @@ struct iommu_ops {
> >  	u32 (*domain_get_windows)(struct iommu_domain *domain);
> >  
> >  	int (*of_xlate)(struct device *dev, struct of_phandle_args
> > *args);
> > +  
> 
> (whitespace change)
will fix, thanks
> 
> >  	bool (*is_attach_deferred)(struct iommu_domain *domain,
> > struct device *dev); 
> > +	int (*bind_pasid_table)(struct iommu_domain *domain,
> > struct device *dev,
> > +				struct pasid_table_config
> > *pasidt_binfo);
> > +	int (*unbind_pasid_table)(struct iommu_domain *domain,
> > +				struct device *dev);
> > +
> >  	unsigned long pgsize_bitmap;
> >  };
> >  
> > @@ -296,6 +305,10 @@ extern int iommu_attach_device(struct
> > iommu_domain *domain, struct device *dev);
> >  extern void iommu_detach_device(struct iommu_domain *domain,
> >  				struct device *dev);
> > +extern int iommu_bind_pasid_table(struct iommu_domain *domain,
> > +		struct device *dev, struct pasid_table_config
> > *pasidt_binfo); +extern int iommu_unbind_pasid_table(struct
> > iommu_domain *domain,
> > +				struct device *dev);
> >  extern struct iommu_domain *iommu_get_domain_for_dev(struct device
> > *dev); extern int iommu_map(struct iommu_domain *domain, unsigned
> > long iova, phys_addr_t paddr, size_t size, int prot);
> > @@ -696,6 +709,18 @@ const struct iommu_ops
> > *iommu_ops_from_fwnode(struct fwnode_handle *fwnode) return NULL;
> >  }
> >  
> > +static inline
> > +int iommu_bind_pasid_table(struct iommu_domain *domain, struct
> > device *dev,
> > +			struct pasid_table_config *pasidt_binfo)
> > +{
> > +	return -EINVAL;
> > +}
> > +static inline
> > +int iommu_unbind_pasid_table(struct iommu_domain *domain, struct
> > device *dev) +{
> > +	return -EINVAL;
> > +}
> > +
> >  #endif /* CONFIG_IOMMU_API */
> >  
> >  #endif /* __LINUX_IOMMU_H */
> > diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> > new file mode 100644
> > index 0000000..aeeaf0e
> > --- /dev/null
> > +++ b/include/uapi/linux/iommu.h
> > @@ -0,0 +1,55 @@
> > +/*
> > + * IOMMU user API definitions
> > + *
> > + *
> > + * This program is free software; you can redistribute it and/or
> > modify
> > + * it under the terms of the GNU General Public License version 2
> > as
> > + * published by the Free Software Foundation.
> > + */
> > +
> > +#ifndef _UAPI_IOMMU_H
> > +#define _UAPI_IOMMU_H
> > +
> > +#include <linux/types.h>
> > +
> > +enum pasid_table_model {
> > +	PASID_TABLE_FORMAT_HOST,
> > +	PASID_TABLE_FORMAT_ARM_1LVL,
> > +	PASID_TABLE_FORMAT_ARM_2LVL,  
> 
> Maybe remove the ARM values and struct for the moment, I'm still not
> sure how to implement it. I think this should be a single ARM_SMMUV3
> model (2LVL might correspond to two different formats in SMMUv3, and
> a future SMMU version could still have 1- or 2-level PASID table but
> incompatible format).
> 
will do, remove the model info is fine for Intel, I guess AMD also?

> > +	PASID_TABLE_FORMAT_AMD,
> > +	PASID_TABLE_FORMAT_INTEL,
> > +};
> > +
> > +/**
> > + * PASID table data used to bind guest PASID table to the host
> > IOMMU. This will
> > + * enable guest managed first level page tables.
> > + * @version: for future extensions and identification of the data
> > format
> > + * @bytes: size of this structure
> > + * @base_ptr:	PASID table pointer
> > + * @pasid_bits:	number of bits supported in the guest PASID
> > table, must be less
> > + *		or equal than the host table size.  
> 
> "host table size" is a bit confusing in this context, especially if
> using multi-level tables. Perhaps it's clear enough that @pasid_bits
> must be smaller or equal than the PASID size supported by the IOMMU,
> and we can remove that second part?
> 
Not sure what is the second part?

> Thanks,
> Jean
> 
> > + * @model:	PASID table format for different IOMMU models
> > + */
> > +struct pasid_table_config {
> > +	__u32 version;
> > +	__u32 bytes;
> > +	__u64 base_ptr;
> > +	__u8 pasid_bits;
> > +	enum pasid_table_model model;
> > +	union {
> > +		struct {
> > +			/* Intel specific fields */
> > +		} intel;
> > +
> > +		struct {
> > +			/* ARM specific fields */
> > +			bool pasid0_dma_no_pasid;
> > +		} arm;
> > +
> > +		struct {
> > +			/* AMD specific fields */
> > +		} amd;
> > +	};
> > +};
> > +
> > +#endif /* _UAPI_IOMMU_H */
> >   
> 

[Jacob Pan]