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

Robin Murphy
2018-03-22T17:22:27Z

On 22/03/18 16:21, Alex Williamson wrote:
> 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,

If it counts, the changes look right, so:

Acked-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>

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;
>