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iommufd: Change the order of MSI setup
Eric points out this is wrong for the rare case of someone using
allow_unsafe_interrupts on ARM. We always have to setup the MSI window in
the domain if the iommu driver asks for it.
Move the iommu_get_msi_cookie() setup to the top of the function and
always do it, regardless of the security mode. Add checks to
iommufd_device_setup_msi() to ensure the driver is not doing something
incomprehensible. No current driver will set both a HW and SW MSI window,
or have more than one SW MSI window.
Fixes: e8d5721003
("iommufd: Add kAPI toward external drivers for physical devices")
Link: https://lore.kernel.org/r/3-v1-0362a1a1c034+98-iommufd_fixes1_jgg@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reported-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
parent
a26fa39206
commit
d6c55c0a20
2 changed files with 39 additions and 41 deletions
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@ -139,19 +139,11 @@ static int iommufd_device_setup_msi(struct iommufd_device *idev,
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int rc;
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/*
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* IOMMU_CAP_INTR_REMAP means that the platform is isolating MSI, and it
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* creates the MSI window by default in the iommu domain. Nothing
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* further to do.
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*/
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if (device_iommu_capable(idev->dev, IOMMU_CAP_INTR_REMAP))
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return 0;
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/*
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* On ARM systems that set the global IRQ_DOMAIN_FLAG_MSI_REMAP every
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* allocated iommu_domain will block interrupts by default and this
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* special flow is needed to turn them back on. iommu_dma_prepare_msi()
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* will install pages into our domain after request_irq() to make this
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* work.
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* If the IOMMU driver gives a IOMMU_RESV_SW_MSI then it is asking us to
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* call iommu_get_msi_cookie() on its behalf. This is necessary to setup
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* the MSI window so iommu_dma_prepare_msi() can install pages into our
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* domain after request_irq(). If it is not done interrupts will not
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* work on this domain.
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*
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* FIXME: This is conceptually broken for iommufd since we want to allow
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* userspace to change the domains, eg switch from an identity IOAS to a
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@ -159,33 +151,35 @@ static int iommufd_device_setup_msi(struct iommufd_device *idev,
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* matches what the IRQ layer actually expects in a newly created
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* domain.
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*/
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if (irq_domain_check_msi_remap()) {
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if (WARN_ON(!sw_msi_start))
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return -EPERM;
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if (sw_msi_start != PHYS_ADDR_MAX && !hwpt->msi_cookie) {
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rc = iommu_get_msi_cookie(hwpt->domain, sw_msi_start);
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if (rc)
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return rc;
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/*
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* iommu_get_msi_cookie() can only be called once per domain,
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* it returns -EBUSY on later calls.
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*/
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if (hwpt->msi_cookie)
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return 0;
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rc = iommu_get_msi_cookie(hwpt->domain, sw_msi_start);
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if (rc)
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return rc;
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hwpt->msi_cookie = true;
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return 0;
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}
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/*
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* Otherwise the platform has a MSI window that is not isolated. For
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* historical compat with VFIO allow a module parameter to ignore the
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* insecurity.
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* For historical compat with VFIO the insecure interrupt path is
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* allowed if the module parameter is set. Insecure means that a MemWr
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* operation from the device (eg a simple DMA) cannot trigger an
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* interrupt outside this iommufd context.
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*/
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if (!allow_unsafe_interrupts)
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return -EPERM;
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if (!device_iommu_capable(idev->dev, IOMMU_CAP_INTR_REMAP) &&
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!irq_domain_check_msi_remap()) {
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if (!allow_unsafe_interrupts)
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return -EPERM;
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dev_warn(
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idev->dev,
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"MSI interrupt window cannot be isolated by the IOMMU, this platform is insecure. Use the \"allow_unsafe_interrupts\" module parameter to override\n");
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dev_warn(
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idev->dev,
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"MSI interrupts are not secure, they cannot be isolated by the platform. "
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"Check that platform features like interrupt remapping are enabled. "
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"Use the \"allow_unsafe_interrupts\" module parameter to override\n");
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}
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return 0;
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}
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@ -203,7 +197,7 @@ static bool iommufd_hw_pagetable_has_group(struct iommufd_hw_pagetable *hwpt,
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static int iommufd_device_do_attach(struct iommufd_device *idev,
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struct iommufd_hw_pagetable *hwpt)
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{
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phys_addr_t sw_msi_start = 0;
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phys_addr_t sw_msi_start = PHYS_ADDR_MAX;
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int rc;
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mutex_lock(&hwpt->devices_lock);
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@ -1170,6 +1170,8 @@ int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt,
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struct iommu_resv_region *resv;
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struct iommu_resv_region *tmp;
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LIST_HEAD(group_resv_regions);
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unsigned int num_hw_msi = 0;
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unsigned int num_sw_msi = 0;
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int rc;
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down_write(&iopt->iova_rwsem);
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@ -1181,23 +1183,25 @@ int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt,
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if (resv->type == IOMMU_RESV_DIRECT_RELAXABLE)
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continue;
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/*
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* The presence of any 'real' MSI regions should take precedence
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* over the software-managed one if the IOMMU driver happens to
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* advertise both types.
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*/
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if (sw_msi_start && resv->type == IOMMU_RESV_MSI) {
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*sw_msi_start = 0;
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sw_msi_start = NULL;
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}
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if (sw_msi_start && resv->type == IOMMU_RESV_SW_MSI)
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if (sw_msi_start && resv->type == IOMMU_RESV_MSI)
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num_hw_msi++;
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if (sw_msi_start && resv->type == IOMMU_RESV_SW_MSI) {
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*sw_msi_start = resv->start;
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num_sw_msi++;
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}
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rc = iopt_reserve_iova(iopt, resv->start,
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resv->length - 1 + resv->start, device);
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if (rc)
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goto out_reserved;
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}
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/* Drivers must offer sane combinations of regions */
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if (WARN_ON(num_sw_msi && num_hw_msi) || WARN_ON(num_sw_msi > 1)) {
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rc = -EINVAL;
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goto out_reserved;
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}
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rc = 0;
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goto out_free_resv;
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