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SubjectRE: [PATCH 5/5] iommu: Add DOMAIN_ATTR_WINDOWS domain attribute
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Hi Joerg,
In case of PAMU, geometry would be meaningless without specifying the number of subwindows. If the API user specifies a geometry but fails to specify the number of required subwindows, we would assume a default (max supported) value, which may be incorrect. It's going to be really ugly. I think we should add the number of sub windows to the domain geometry. This parameter would be used in case of a window based iommu. So, a separate set_window API wouldn't be required.

We can still implement the get_windows API for getting the maximum number of subwindows supported by the window based IOMMU.

Regards
Varun

> -----Original Message-----
> From: Joerg Roedel [mailto:joro@8bytes.org]
> Sent: Monday, February 04, 2013 6:49 PM
> To: Sethi Varun-B16395; Stuart Yoder
> Cc: iommu@lists.linux-foundation.org; linux-kernel@vger.kernel.org; Joerg
> Roedel
> Subject: [PATCH 5/5] iommu: Add DOMAIN_ATTR_WINDOWS domain attribute
>
> This attribute can be used to set and get the number of subwindows on
> IOMMUs that are window-based.
>
> Signed-off-by: Joerg Roedel <joro@8bytes.org>
> ---
> drivers/iommu/iommu.c | 33 ++++++++++++++++++++++++++++++---
> include/linux/iommu.h | 5 +++++
> 2 files changed, 35 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index
> 0fdb7db..66402f7 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -891,6 +891,7 @@ int iommu_domain_get_attr(struct iommu_domain
> *domain,
> struct iommu_domain_geometry *geometry;
> bool *paging;
> int ret = 0;
> + u32 *count;
>
> switch (attr) {
> case DOMAIN_ATTR_GEOMETRY:
> @@ -902,6 +903,15 @@ int iommu_domain_get_attr(struct iommu_domain
> *domain,
> paging = data;
> *paging = (domain->ops->pgsize_bitmap != 0UL);
> break;
> + case DOMAIN_ATTR_WINDOWS:
> + count = data;
> +
> + if (domain->ops->domain_get_windows != NULL)
> + *count = domain->ops->domain_get_windows(domain);
> + else
> + ret = -ENODEV;
> +
> + break;
> default:
> if (!domain->ops->domain_get_attr)
> return -EINVAL;
> @@ -916,9 +926,26 @@ EXPORT_SYMBOL_GPL(iommu_domain_get_attr);
> int iommu_domain_set_attr(struct iommu_domain *domain,
> enum iommu_attr attr, void *data)
> {
> - if (!domain->ops->domain_set_attr)
> - return -EINVAL;
> + int ret = 0;
> + u32 *count;
> +
> + switch (attr) {
> + case DOMAIN_ATTR_WINDOWS:
> + count = data;
> +
> + if (domain->ops->domain_set_windows != NULL)
> + ret = domain->ops->domain_set_windows(domain, *count);
> + else
> + ret = -ENODEV;
>
> - return domain->ops->domain_set_attr(domain, attr, data);
> + break;
> + default:
> + if (domain->ops->domain_set_attr == NULL)
> + return -EINVAL;
> +
> + ret = domain->ops->domain_set_attr(domain, attr, data);
> + }
> +
> + return ret;
> }
> EXPORT_SYMBOL_GPL(iommu_domain_set_attr);
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h index
> 0cba2d8..8330df1 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -60,6 +60,7 @@ struct iommu_domain {
> enum iommu_attr {
> DOMAIN_ATTR_GEOMETRY,
> DOMAIN_ATTR_PAGING,
> + DOMAIN_ATTR_WINDOWS,
> DOMAIN_ATTR_MAX,
> };
>
> @@ -106,6 +107,10 @@ struct iommu_ops {
> int (*domain_window_enable)(struct iommu_domain *domain, u32
> wnd_nr,
> phys_addr_t paddr, size_t size);
> void (*domain_window_disable)(struct iommu_domain *domain, u32
> wnd_nr);
> + /* Set the numer of window per domain */
> + int (*domain_set_windows)(struct iommu_domain *domain, u32
> w_count);
> + /* Get the numer of window per domain */
> + u32 (*domain_get_windows)(struct iommu_domain *domain);
>
> unsigned long pgsize_bitmap;
> };
> --
> 1.7.9.5
>
>




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