2021-09-19 12:16:57

by Yi Liu

Subject: [RFC 09/20] iommu: Add page size and address width attributes

From: Lu Baolu <[email protected]>

This exposes PAGE_SIZE and ADDR_WIDTH attributes. The iommufd could use
them to define the IOAS.

Signed-off-by: Lu Baolu <[email protected]>
---
include/linux/iommu.h | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 943de6897f56..86d34e4ce05e 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -153,9 +153,13 @@ enum iommu_dev_features {
/**
* enum iommu_devattr - Per device IOMMU attributes
* @IOMMU_DEV_INFO_FORCE_SNOOP [bool]: IOMMU can force DMA to be snooped.
+ * @IOMMU_DEV_INFO_PAGE_SIZE [u64]: Page sizes that iommu supports.
+ * @IOMMU_DEV_INFO_ADDR_WIDTH [u32]: Address width supported.
*/
enum iommu_devattr {
IOMMU_DEV_INFO_FORCE_SNOOP,
+ IOMMU_DEV_INFO_PAGE_SIZE,
+ IOMMU_DEV_INFO_ADDR_WIDTH,
};

#define IOMMU_PASID_INVALID (-1U)
--
2.25.1

2021-09-22 13:47:27

by Eric Auger

Subject: Re: [RFC 09/20] iommu: Add page size and address width attributes

Hi,

On 9/19/21 8:38 AM, Liu Yi L wrote:
> From: Lu Baolu <[email protected]>
>
> This exposes PAGE_SIZE and ADDR_WIDTH attributes. The iommufd could use
> them to define the IOAS.
>
> Signed-off-by: Lu Baolu <[email protected]>
> ---
> include/linux/iommu.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 943de6897f56..86d34e4ce05e 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -153,9 +153,13 @@ enum iommu_dev_features {
> /**
> * enum iommu_devattr - Per device IOMMU attributes
> * @IOMMU_DEV_INFO_FORCE_SNOOP [bool]: IOMMU can force DMA to be snooped.
> + * @IOMMU_DEV_INFO_PAGE_SIZE [u64]: Page sizes that iommu supports.
> + * @IOMMU_DEV_INFO_ADDR_WIDTH [u32]: Address width supported.
I think this deserves additional info. What address width do we talk
about, input, output, what stage if the IOMMU does support multiple stages

Thanks

Eric
> */
> enum iommu_devattr {
> IOMMU_DEV_INFO_FORCE_SNOOP,
> + IOMMU_DEV_INFO_PAGE_SIZE,
> + IOMMU_DEV_INFO_ADDR_WIDTH,
> };
>
> #define IOMMU_PASID_INVALID (-1U)

2021-09-22 14:21:32

by Tian, Kevin

Subject: RE: [RFC 09/20] iommu: Add page size and address width attributes

> From: Eric Auger <[email protected]>
> Sent: Wednesday, September 22, 2021 9:43 PM
>
> Hi,
>
> On 9/19/21 8:38 AM, Liu Yi L wrote:
> > From: Lu Baolu <[email protected]>
> >
> > This exposes PAGE_SIZE and ADDR_WIDTH attributes. The iommufd could
> use
> > them to define the IOAS.
> >
> > Signed-off-by: Lu Baolu <[email protected]>
> > ---
> > include/linux/iommu.h | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > index 943de6897f56..86d34e4ce05e 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -153,9 +153,13 @@ enum iommu_dev_features {
> > /**
> > * enum iommu_devattr - Per device IOMMU attributes
> > * @IOMMU_DEV_INFO_FORCE_SNOOP [bool]: IOMMU can force DMA to
> be snooped.
> > + * @IOMMU_DEV_INFO_PAGE_SIZE [u64]: Page sizes that iommu
> supports.
> > + * @IOMMU_DEV_INFO_ADDR_WIDTH [u32]: Address width supported.
> I think this deserves additional info. What address width do we talk
> about, input, output, what stage if the IOMMU does support multiple stages
>

it describes the address space width, thus is about input.

when multiple stages are supported, each stage is represented by a separate
ioasid, each with its own addr_width