On 2022/11/8 08:49, Jason Gunthorpe wrote:
Add the four functions external drivers need to connect physical DMA to
the IOMMUFD:
iommufd_device_bind() / iommufd_device_unbind()
Register the device with iommufd and establish security isolation.
iommufd_device_attach() / iommufd_device_detach()
Connect a bound device to a page table
Binding a device creates a device object ID in the uAPI, however the
generic API provides no IOCTLs to manipulate them.
Tested-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
drivers/iommu/iommufd/Makefile | 1 +
drivers/iommu/iommufd/device.c | 402 ++++++++++++++++++++++++
drivers/iommu/iommufd/iommufd_private.h | 5 +
drivers/iommu/iommufd/main.c | 3 +
include/linux/iommufd.h | 13 +
5 files changed, 424 insertions(+)
create mode 100644 drivers/iommu/iommufd/device.c
diff --git a/drivers/iommu/iommufd/Makefile b/drivers/iommu/iommufd/Makefile
index e13e971aa28c60..ca28a135b9675f 100644
--- a/drivers/iommu/iommufd/Makefile
+++ b/drivers/iommu/iommufd/Makefile
@@ -1,5 +1,6 @@
# SPDX-License-Identifier: GPL-2.0-only
iommufd-y := \
+ device.o \
hw_pagetable.o \
io_pagetable.o \
ioas.o \
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
new file mode 100644
index 00000000000000..a3bf3c07d3f800
--- /dev/null
+++ b/drivers/iommu/iommufd/device.c
@@ -0,0 +1,402 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES
+ */
+#include <linux/iommufd.h>
+#include <linux/slab.h>
+#include <linux/iommu.h>
+#include <linux/irqdomain.h>
+
+#include "iommufd_private.h"
+
+/*
+ * A iommufd_device object represents the binding relationship between a
+ * consuming driver and the iommufd. These objects are created/destroyed by
+ * external drivers, not by userspace.
+ */
+struct iommufd_device {
+ struct iommufd_object obj;
+ struct iommufd_ctx *ictx;
+ struct iommufd_hw_pagetable *hwpt;
+ /* Head at iommufd_hw_pagetable::devices */
+ struct list_head devices_item;
+ /* always the physical device */
+ struct device *dev;
+ struct iommu_group *group;
+ bool enforce_cache_coherency;
+};
+
+void iommufd_device_destroy(struct iommufd_object *obj)
+{
+ struct iommufd_device *idev =
+ container_of(obj, struct iommufd_device, obj);
+
+ iommu_device_release_dma_owner(idev->dev);
+ iommu_group_put(idev->group);
+ iommufd_ctx_put(idev->ictx);
+}
+
+/**
+ * iommufd_device_bind - Bind a physical device to an iommu fd
+ * @ictx: iommufd file descriptor
+ * @dev: Pointer to a physical PCI device struct
+ * @id: Output ID number to return to userspace for this device
+ *
+ * A successful bind establishes an ownership over the device and returns
+ * struct iommufd_device pointer, otherwise returns error pointer.
+ *
+ * A driver using this API must set driver_managed_dma and must not touch
+ * the device until this routine succeeds and establishes ownership.
+ *
+ * Binding a PCI device places the entire RID under iommufd control.
+ *
+ * The caller must undo this with iommufd_unbind_device()
it should be iommufd_device_unbind() now.
+ */
+struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
+ struct device *dev, u32 *id)
+{
+ struct iommufd_device *idev;
+ struct iommu_group *group;
+ int rc;
+
+ /*
+ * iommufd always sets IOMMU_CACHE because we offer no way for userspace
+ * to restore cache coherency.
+ */
+ if (!device_iommu_capable(dev, IOMMU_CAP_CACHE_COHERENCY))
+ return ERR_PTR(-EINVAL);
+
+ group = iommu_group_get(dev);
+ if (!group)
+ return ERR_PTR(-ENODEV);
+
+ rc = iommu_device_claim_dma_owner(dev, ictx);
+ if (rc)
+ goto out_group_put;
+
+ idev = iommufd_object_alloc(ictx, idev, IOMMUFD_OBJ_DEVICE);
+ if (IS_ERR(idev)) {
+ rc = PTR_ERR(idev);
+ goto out_release_owner;
+ }
+ idev->ictx = ictx;
+ iommufd_ctx_get(ictx);
+ idev->dev = dev;
+ idev->enforce_cache_coherency =
+ device_iommu_capable(dev, IOMMU_CAP_ENFORCE_CACHE_COHERENCY);
+ /* The calling driver is a user until iommufd_device_unbind() */
+ refcount_inc(&idev->obj.users);
+ /* group refcount moves into iommufd_device */
+ idev->group = group;
+
+ /*
+ * If the caller fails after this success it must call
+ * iommufd_unbind_device() which is safe since we hold this refcount.
+ * This also means the device is a leaf in the graph and no other object
+ * can take a reference on it.
+ */
+ iommufd_object_finalize(ictx, &idev->obj);
+ *id = idev->obj.id;
+ return idev;
+
+out_release_owner:
+ iommu_device_release_dma_owner(dev);
+out_group_put:
+ iommu_group_put(group);
+ return ERR_PTR(rc);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_device_bind, IOMMUFD);
+
+void iommufd_device_unbind(struct iommufd_device *idev)
+{
+ bool was_destroyed;
+
+ was_destroyed = iommufd_object_destroy_user(idev->ictx, &idev->obj);
+ WARN_ON(!was_destroyed);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_device_unbind, IOMMUFD);
+
+static int iommufd_device_setup_msi(struct iommufd_device *idev,
+ struct iommufd_hw_pagetable *hwpt,
+ phys_addr_t sw_msi_start,
+ unsigned int flags)
+{
+ int rc;
+
+ /*
+ * IOMMU_CAP_INTR_REMAP means that the platform is isolating MSI, and it
+ * creates the MSI window by default in the iommu domain. Nothing
+ * further to do.
+ */
+ if (device_iommu_capable(idev->dev, IOMMU_CAP_INTR_REMAP))
+ return 0;
+
+ /*
+ * On ARM systems that set the global IRQ_DOMAIN_FLAG_MSI_REMAP every
+ * allocated iommu_domain will block interrupts by default and this
+ * special flow is needed to turn them back on. iommu_dma_prepare_msi()
+ * will install pages into our domain after request_irq() to make this
+ * work.
+ *
+ * FIXME: This is conceptually broken for iommufd since we want to allow
+ * userspace to change the domains, eg switch from an identity IOAS to a
+ * DMA IOAS. There is currently no way to create a MSI window that
+ * matches what the IRQ layer actually expects in a newly created
+ * domain.
+ */
+ if (irq_domain_check_msi_remap()) {
+ if (WARN_ON(!sw_msi_start))
+ return -EPERM;
+ /*
+ * iommu_get_msi_cookie() can only be called once per domain,
+ * it returns -EBUSY on later calls.
+ */
+ if (hwpt->msi_cookie)
+ return 0;
+ rc = iommu_get_msi_cookie(hwpt->domain, sw_msi_start);
+ if (rc)
+ return rc;
+ hwpt->msi_cookie = true;
+ return 0;
+ }
+
+ /*
+ * Otherwise the platform has a MSI window that is not isolated. For
+ * historical compat with VFIO allow a module parameter to ignore the
+ * insecurity.
+ */
+ if (!(flags & IOMMUFD_ATTACH_FLAGS_ALLOW_UNSAFE_INTERRUPT))
+ return -EPERM;
+ else
+ dev_warn(
+ idev->dev,
+ "Device interrupts cannot be isolated by the IOMMU, this platform in insecure. Use an \"allow_unsafe_interrupts\" module parameter to override\n");
+
+ return 0;
+}
+
+static bool iommufd_hw_pagetable_has_group(struct iommufd_hw_pagetable *hwpt,
+ struct iommu_group *group)
+{
+ struct iommufd_device *cur_dev;
+
+ list_for_each_entry(cur_dev, &hwpt->devices, devices_item)
+ if (cur_dev->group == group)
+ return true;
+ return false;
+}
+
+static int iommufd_device_do_attach(struct iommufd_device *idev,
+ struct iommufd_hw_pagetable *hwpt,
+ unsigned int flags)
+{
+ phys_addr_t sw_msi_start = 0;
+ int rc;
+
+ mutex_lock(&hwpt->devices_lock);
+
+ /*
+ * Try to upgrade the domain we have, it is an iommu driver bug to
+ * report IOMMU_CAP_ENFORCE_CACHE_COHERENCY but fail
+ * enforce_cache_coherency when there are no devices attached to the
+ * domain.
+ */
+ if (idev->enforce_cache_coherency && !hwpt->enforce_cache_coherency) {
+ if (hwpt->domain->ops->enforce_cache_coherency)
+ hwpt->enforce_cache_coherency =
+ hwpt->domain->ops->enforce_cache_coherency(
+ hwpt->domain);
+ if (!hwpt->enforce_cache_coherency) {
+ WARN_ON(list_empty(&hwpt->devices));
+ rc = -EINVAL;
+ goto out_unlock;
+ }
+ }
+
+ rc = iopt_table_enforce_group_resv_regions(&hwpt->ioas->iopt, idev->dev,
+ idev->group, &sw_msi_start);
+ if (rc)
+ goto out_unlock;
+
+ rc = iommufd_device_setup_msi(idev, hwpt, sw_msi_start, flags);
+ if (rc)
+ goto out_iova;
aren't the above two operations only once for a group? I remember you did
the two after iommu_attach_group().
+ /*
+ * FIXME: Hack around missing a device-centric iommu api, only attach to
+ * the group once for the first device that is in the group.
+ */
+ if (!iommufd_hw_pagetable_has_group(hwpt, idev->group)) {
+ rc = iommu_attach_group(hwpt->domain, idev->group);
+ if (rc)
+ goto out_iova;
+
+ if (list_empty(&hwpt->devices)) {
+ rc = iopt_table_add_domain(&hwpt->ioas->iopt,
+ hwpt->domain);
+ if (rc)
+ goto out_detach;
+ }
+ }
+
+ idev->hwpt = hwpt;
+ refcount_inc(&hwpt->obj.users);
+ list_add(&idev->devices_item, &hwpt->devices);
+ mutex_unlock(&hwpt->devices_lock);
+ return 0;
+
+out_detach:
+ iommu_detach_group(hwpt->domain, idev->group);
+out_iova:
+ iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->dev);
+out_unlock:
+ mutex_unlock(&hwpt->devices_lock);
+ return rc;
+}
+
--
Regards,
Yi Liu
