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

Alex Williamson
2018-03-22T16:21:48Z

On Thu, 15 Mar 2018 16:35:09 +0000
Shameer Kolothum <shameerali.kolothum.thodi-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> 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-5wv7dgnIgG8@public.gmane.org>
> Cc: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> ---

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,

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;