Re: [PATCH v5 7/7] iommu/dma: Move PCI window region reservation back into dma specific path.

[Robin Murphy <robin.murphy@xxxxxxx>]

On 22/03/18 16:21, Alex Williamson wrote:
> On Thu, 15 Mar 2018 16:35:09 +0000
> Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx> wrote:
>
> > This pretty much reverts commit 273df9635385 ("iommu/dma: Make PCI
> > window reservation generic")  by moving the PCI window region
> > reservation back into the dma specific path so that these regions
> > doesn't get exposed via the IOMMU API interface. With this change,
> > the vfio interface will report only iommu specific reserved regions
> > to the user space.
> >
> > Cc: Robin Murphy <robin.murphy@xxxxxxx>
> > Cc: Joerg Roedel <joro@xxxxxxxxxx>
> > Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> > ---
>
> As currently ordered, we expose the iova list to the user in 5/7 with
> the PCI window reservations still intact.  Isn't that a bisection
> problem?  This patch should come before the iova list is expose to the
> user.  This is otherwise independent, so I can pop it up in the stack on
> commit, but I'd need an ack from Joerg and Robin to take it via my
> tree.  Thanks,

If it counts, the changes look right, so:

Acked-by: Robin Murphy <robin.murphy@xxxxxxx>

but it does look like there's a hard dependency on Joerg's core branch 
where Shameer's ITS workaround patches are currently queued. Otherwise, 
though, I don't think there's anything else due to be touching iommu-dma 
just yet.

Robin.

> Alex
>
> >   drivers/iommu/dma-iommu.c | 54 ++++++++++++++++++++++-------------------------
> >   1 file changed, 25 insertions(+), 29 deletions(-)
> >
> > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> > index f05f3cf..ddcbbdb 100644
> > --- a/drivers/iommu/dma-iommu.c
> > +++ b/drivers/iommu/dma-iommu.c
> > @@ -167,40 +167,16 @@ EXPORT_SYMBOL(iommu_put_dma_cookie);
> >    * @list: Reserved region list from iommu_get_resv_regions()
> >    *
> >    * IOMMU drivers can use this to implement their .get_resv_regions callback
> > - * for general non-IOMMU-specific reservations. Currently, this covers host
> > - * bridge windows for PCI devices and GICv3 ITS region reservation on ACPI
> > - * based ARM platforms that may require HW MSI reservation.
> > + * for general non-IOMMU-specific reservations. Currently, this covers GICv3
> > + * ITS region reservation on ACPI based ARM platforms that may require HW MSI
> > + * reservation.
> >    */
> >   void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
> >   {
> > -	struct pci_host_bridge *bridge;
> > -	struct resource_entry *window;
> > -
> > -	if (!is_of_node(dev->iommu_fwspec->iommu_fwnode) &&
> > -		iort_iommu_msi_get_resv_regions(dev, list) < 0)
> > -		return;
> > -
> > -	if (!dev_is_pci(dev))
> > -		return;
> > -
> > -	bridge = pci_find_host_bridge(to_pci_dev(dev)->bus);
> > -	resource_list_for_each_entry(window, &bridge->windows) {
> > -		struct iommu_resv_region *region;
> > -		phys_addr_t start;
> > -		size_t length;
> > -
> > -		if (resource_type(window->res) != IORESOURCE_MEM)
> > -			continue;
> >   
> > -		start = window->res->start - window->offset;
> > -		length = window->res->end - window->res->start + 1;
> > -		region = iommu_alloc_resv_region(start, length, 0,
> > -				IOMMU_RESV_RESERVED);
> > -		if (!region)
> > -			return;
> > +	if (!is_of_node(dev->iommu_fwspec->iommu_fwnode))
> > +		iort_iommu_msi_get_resv_regions(dev, list);
> >   
> > -		list_add_tail(&region->list, list);
> > -	}
> >   }
> >   EXPORT_SYMBOL(iommu_dma_get_resv_regions);
> >   
> > @@ -229,6 +205,23 @@ static int cookie_init_hw_msi_region(struct iommu_dma_cookie *cookie,
> >   	return 0;
> >   }
> >   
> > +static void iova_reserve_pci_windows(struct pci_dev *dev,
> > +		struct iova_domain *iovad)
> > +{
> > +	struct pci_host_bridge *bridge = pci_find_host_bridge(dev->bus);
> > +	struct resource_entry *window;
> > +	unsigned long lo, hi;
> > +
> > +	resource_list_for_each_entry(window, &bridge->windows) {
> > +		if (resource_type(window->res) != IORESOURCE_MEM)
> > +			continue;
> > +
> > +		lo = iova_pfn(iovad, window->res->start - window->offset);
> > +		hi = iova_pfn(iovad, window->res->end - window->offset);
> > +		reserve_iova(iovad, lo, hi);
> > +	}
> > +}
> > +
> >   static int iova_reserve_iommu_regions(struct device *dev,
> >   		struct iommu_domain *domain)
> >   {
> > @@ -238,6 +231,9 @@ static int iova_reserve_iommu_regions(struct device *dev,
> >   	LIST_HEAD(resv_regions);
> >   	int ret = 0;
> >   
> > +	if (dev_is_pci(dev))
> > +		iova_reserve_pci_windows(to_pci_dev(dev), iovad);
> > +
> >   	iommu_get_resv_regions(dev, &resv_regions);
> >   	list_for_each_entry(region, &resv_regions, list) {
> >   		unsigned long lo, hi;