Messages in this thread | | | Subject | Re: [PATCH v1] iommu/s390: Declare s390 iommu reserved regions | From | Pierre Morel <> | Date | Wed, 16 Jan 2019 10:33:52 +0100 |
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On 15/01/2019 20:33, Gerald Schaefer wrote: > On Tue, 15 Jan 2019 18:37:30 +0100 > Pierre Morel <pmorel@linux.ibm.com> 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@linux.ibm.com> >> --- >> 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@de.ibm.com> >
Thanks.
Regards, Pierre
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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