On 15/01/2019 20:33, Gerald Schaefer wrote:
On Tue, 15 Jan 2019 18:37:30 +0100 Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:The s390 iommu can only allow DMA transactions between the zPCI device entries start_dma and end_dma. Let's declare the regions before start_dma and after end_dma as reserved regions using the appropriate callback in iommu_ops. Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx> --- drivers/iommu/s390-iommu.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c index 22d4db3..5ca91a1 100644 --- a/drivers/iommu/s390-iommu.c +++ b/drivers/iommu/s390-iommu.c @@ -363,6 +363,33 @@ void zpci_destroy_iommu(struct zpci_dev *zdev) iommu_device_sysfs_remove(&zdev->iommu_dev); } +static void s390_get_resv_regions(struct device *dev, struct list_head *head) +{ + struct iommu_resv_region *region; + struct zpci_dev *zdev = to_pci_dev(dev)->sysdata; + + region = iommu_alloc_resv_region(0, zdev->start_dma, + 0, IOMMU_RESV_RESERVED); + if (!region) + return; + list_add_tail(®ion->list, head); + + region = iommu_alloc_resv_region(zdev->end_dma + 1, + ~0UL - zdev->end_dma, + 0, IOMMU_RESV_RESERVED);Can you guarantee that start_dma will never be 0 and end_dma never ~0UL, even with future HW? In any of these cases, your code would reserve strange ranges, and sysfs would report broken reserved ranges. Maybe add a check for start_dma > 0 and end_dma < ULONG_MAX?
Yes, thanks.
+ if (!region) + return; + list_add_tail(®ion->list, head); +} + +static void s390_put_resv_regions(struct device *dev, struct list_head *head) +{ + struct iommu_resv_region *entry, *next; + + list_for_each_entry_safe(entry, next, head, list) + kfree(entry); +}It looks very wrong that there is no matching list_del() for the previous list_add_tail(). However, it seems to be done like this everywhere else, and the calling functions (currently) only use temporary list_heads as far as I can see, so I guess it should be OK (for now). Still, a list_del() would be nice :-)
hum. right.
+ static const struct iommu_ops s390_iommu_ops = { .capable = s390_iommu_capable, .domain_alloc = s390_domain_alloc, @@ -376,6 +403,8 @@ static const struct iommu_ops s390_iommu_ops = { .remove_device = s390_iommu_remove_device, .device_group = generic_device_group, .pgsize_bitmap = S390_IOMMU_PGSIZES, + .get_resv_regions = s390_get_resv_regions, + .put_resv_regions = s390_put_resv_regions, }; static int __init s390_iommu_init(void)With the start/end_dma issue addressed (if necessary): Acked-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Thanks. Regards, Pierre -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
