Re: [PATCH 20/20] iommu: Convert remaining simple drivers to domain_alloc_paging()
From: Niklas Schnelle <schnelle@linux.ibm.com>
Date: 2023-05-02 14:54:04
Also in:
linux-arm-msm, linux-iommu, linux-mediatek, linux-rockchip, linux-s390, linux-samsung-soc, linux-sunxi, linux-tegra
On Mon, 2023-05-01 at 15:03 -0300, Jason Gunthorpe wrote:
These drivers don't support IOMMU_DOMAIN_DMA, so this commit effectively allows them to support that mode. The prior work to require default_domains makes this safe because every one of these drivers is either compilation incompatible with dma-iommu.c, or already establishing a default_domain. In both cases alloc_domain() will never be called with IOMMU_DOMAIN_DMA for these drivers so it is safe to drop the test. Removing these tests clarifies that the domain allocation path is only about the functionality of a paging domain and has nothing to do with policy of how the paging domain is used for UNMANAGED/DMA/DMA_FQ. Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> --- drivers/iommu/fsl_pamu_domain.c | 7 ++----- drivers/iommu/msm_iommu.c | 7 ++----- drivers/iommu/mtk_iommu_v1.c | 7 ++----- drivers/iommu/omap-iommu.c | 7 ++----- drivers/iommu/s390-iommu.c | 7 ++----- drivers/iommu/tegra-gart.c | 7 ++----- 6 files changed, 12 insertions(+), 30 deletions(-)
---8<---
quoted hunk ↗ jump to hunk
-static struct iommu_domain *s390_domain_alloc(unsigned domain_type) +static struct iommu_domain *s390_domain_alloc_paging(struct device *dev) { struct s390_domain *s390_domain; - if (domain_type != IOMMU_DOMAIN_UNMANAGED) - return NULL; - s390_domain = kzalloc(sizeof(*s390_domain), GFP_KERNEL); if (!s390_domain) return NULL;@@ -447,7 +444,7 @@ void zpci_destroy_iommu(struct zpci_dev *zdev) static const struct iommu_ops s390_iommu_ops = { .default_domain = &s390_iommu_platform_domain, .capable = s390_iommu_capable, - .domain_alloc = s390_domain_alloc, + .domain_alloc_paging = s390_domain_alloc_paging,
Leaving .domain_alloc unset here leads to an OOPs with your GitHub
branch (iommu_mandatory_default) when I try to use vfio-pci for KVM
pass-through via the following call chain:
...
vfio_group_fops_unl_ioctl()
vfio_group_ioctl_set_container()
vfio_container_attach_group()
iommu_group_claim_dma_owner()
__iommu_take_dma_ownership()
__iommu_group_alloc_blocking_domain()
__iommu_domain_alloc(…, IOMMU_DOMAIN_BLOCKED)
The problem is that in __iommu_domain_alloc() a call to bus->iommu_ops-domain_alloc() is attempted for IOMMU_DOMAIN_BLCOKED even if the
function pointer is unset. So I tried with the obvious fix:
@@ -1947,7 +1948,7 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, if ((type == IOMMU_DOMAIN_UNMANAGED || type == IOMMU_DOMAIN_DMA) && bus->iommu_ops->domain_alloc_paging) domain = bus->iommu_ops->domain_alloc_paging(dev); - else + else if (bus->iommu_ops->domain_alloc) domain = bus->iommu_ops->domain_alloc(type); if (!domain) return NULL;
This then uses the fallback of an empty IOMMU_DOMAIN_UNMANAGED and I get a working device in the guest. Also tried hot unplug where the device is taken over by the host again. I think with my DMA API conversion patches we can support blocking domains properly but for a temporary solution the above may be acceptable.
.probe_device = s390_iommu_probe_device, .release_device = s390_iommu_release_device, .device_group = generic_device_group,
_______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel