Re: [PATCH v8 16/18] vfio/type1: Allow transparent MSI IOVA allocation

From: Alex Williamson
Date: Fri Jan 13 2017 - 18:06:13 EST


On Wed, 11 Jan 2017 09:41:52 +0000
Eric Auger <eric.auger@xxxxxxxxxx> wrote:

> When attaching a group to the container, check the group's
> reserved regions and test whether the IOMMU translates MSI
> transactions. If yes, we initialize an IOVA allocator through
> the iommu_get_msi_cookie API. This will allow the MSI IOVAs
> to be transparently allocated on MSI controller's compose().
>
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>


Acked-by: Alex Williamson <alex.williamson@xxxxxxxxxx>


> ---
>
> v3 -> v4:
> - test region's type: IOMMU_RESV_MSI
> - restructure the code to prepare for safety assessment
> - reword title
> ---
> drivers/vfio/vfio_iommu_type1.c | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 9266271..5651faf 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -39,6 +39,7 @@
> #include <linux/pid_namespace.h>
> #include <linux/mdev.h>
> #include <linux/notifier.h>
> +#include <linux/dma-iommu.h>
>
> #define DRIVER_VERSION "0.2"
> #define DRIVER_AUTHOR "Alex Williamson <alex.williamson@xxxxxxxxxx>"
> @@ -1181,6 +1182,28 @@ static struct vfio_group *find_iommu_group(struct vfio_domain *domain,
> return NULL;
> }
>
> +static bool vfio_iommu_has_resv_msi(struct iommu_group *group,
> + phys_addr_t *base)
> +{
> + struct list_head group_resv_regions;
> + struct iommu_resv_region *region, *next;
> + bool ret = false;
> +
> + INIT_LIST_HEAD(&group_resv_regions);
> + iommu_get_group_resv_regions(group, &group_resv_regions);
> + list_for_each_entry(region, &group_resv_regions, list) {
> + if (region->type & IOMMU_RESV_MSI) {
> + *base = region->start;
> + ret = true;
> + goto out;
> + }
> + }
> +out:
> + list_for_each_entry_safe(region, next, &group_resv_regions, list)
> + kfree(region);
> + return ret;
> +}
> +
> static int vfio_iommu_type1_attach_group(void *iommu_data,
> struct iommu_group *iommu_group)
> {
> @@ -1189,6 +1212,8 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> struct vfio_domain *domain, *d;
> struct bus_type *bus = NULL, *mdev_bus;
> int ret;
> + bool resv_msi;
> + phys_addr_t resv_msi_base;
>
> mutex_lock(&iommu->lock);
>
> @@ -1258,6 +1283,8 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> if (ret)
> goto out_domain;
>
> + resv_msi = vfio_iommu_has_resv_msi(iommu_group, &resv_msi_base);
> +
> INIT_LIST_HEAD(&domain->group_list);
> list_add(&group->next, &domain->group_list);
>
> @@ -1304,6 +1331,9 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> if (ret)
> goto out_detach;
>
> + if (resv_msi && iommu_get_msi_cookie(domain->domain, resv_msi_base))
> + goto out_detach;
> +
> list_add(&domain->next, &iommu->domain_list);
>
> mutex_unlock(&iommu->lock);