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

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Date:   Fri, 13 Jan 2017 16:04:56 -0700
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Eric Auger <eric.auger@...hat.com>
Cc:     eric.auger.pro@...il.com, christoffer.dall@...aro.org,
        marc.zyngier@....com, robin.murphy@....com, will.deacon@....com,
        joro@...tes.org, tglx@...utronix.de, jason@...edaemon.net,
        linux-arm-kernel@...ts.infradead.org, kvm@...r.kernel.org,
        drjones@...hat.com, linux-kernel@...r.kernel.org,
        pranav.sawargaonkar@...il.com, iommu@...ts.linux-foundation.org,
        punit.agrawal@....com, diana.craciun@....com, gpkulkarni@...il.com,
        shankerd@...eaurora.org, bharat.bhushan@....com,
        geethasowjanya.akula@...il.com
Subject: Re: [PATCH v8 16/18] vfio/type1: Allow transparent MSI IOVA
 allocation

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


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


> ---
> 
> 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@...hat.com>"
> @@ -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);