@@ -26,6 +26,11 @@ void acpi_arch_dma_setup(struct device *dev)
else
end = (1ULL << 32) - 1;
+ if (dev->dma_range_map) {
+ dev_dbg(dev, "dma_range_map already set\n");
+ return;
+ }
+
ret = acpi_dma_get_range(dev, &map);
if (!ret && map) {
end = dma_range_map_max(map);
@@ -1632,13 +1632,6 @@ static int acpi_iommu_configure_id(struct device *dev, const u32 *id_in)
err = viot_iommu_configure(dev);
mutex_unlock(&iommu_probe_device_lock);
- /*
- * If we have reason to believe the IOMMU driver missed the initial
- * iommu_probe_device() call for dev, replay it to get things in order.
- */
- if (!err && dev->bus)
- err = iommu_probe_device(dev);
-
return err;
}
@@ -364,7 +364,8 @@ static int amba_dma_configure(struct device *dev)
ret = acpi_dma_configure(dev, attr);
}
- if (!ret && !drv->driver_managed_dma) {
+ /* @drv may not be valid when we're called from the IOMMU layer */
+ if (!ret && dev->driver && !drv->driver_managed_dma) {
ret = iommu_device_use_default_domain(dev);
if (ret)
arch_teardown_dma_ops(dev);
@@ -1451,7 +1451,8 @@ static int platform_dma_configure(struct device *dev)
attr = acpi_get_dma_attr(to_acpi_device_node(fwnode));
ret = acpi_dma_configure(dev, attr);
}
- if (ret || drv->driver_managed_dma)
+ /* @drv may not be valid when we're called from the IOMMU layer */
+ if (ret || !dev->driver || drv->driver_managed_dma)
return ret;
ret = iommu_device_use_default_domain(dev);
@@ -153,7 +153,8 @@ static int fsl_mc_dma_configure(struct device *dev)
else
ret = acpi_dma_configure_id(dev, DEV_DMA_COHERENT, &input_id);
- if (!ret && !mc_drv->driver_managed_dma) {
+ /* @mc_drv may not be valid when we're called from the IOMMU layer */
+ if (!ret && dev->driver && !mc_drv->driver_managed_dma) {
ret = iommu_device_use_default_domain(dev);
if (ret)
arch_teardown_dma_ops(dev);
@@ -360,7 +360,8 @@ static int cdx_dma_configure(struct device *dev)
return ret;
}
- if (!ret && !cdx_drv->driver_managed_dma) {
+ /* @cdx_drv may not be valid when we're called from the IOMMU layer */
+ if (!ret && dev->driver && !cdx_drv->driver_managed_dma) {
ret = iommu_device_use_default_domain(dev);
if (ret)
arch_teardown_dma_ops(dev);
@@ -414,9 +414,21 @@ static int iommu_init_device(struct device *dev)
if (!dev_iommu_get(dev))
return -ENOMEM;
/*
- * For FDT-based systems and ACPI IORT/VIOT, drivers register IOMMU
- * instances with non-NULL fwnodes, and client devices should have been
- * identified with a fwspec by this point. Otherwise, we can currently
+ * For FDT-based systems and ACPI IORT/VIOT, the common firmware parsing
+ * is buried in the bus dma_configure path. Properly unpicking that is
+ * still a big job, so for now just invoke the whole thing. The device
+ * already having a driver bound means dma_configure has already run and
+ * either found no IOMMU to wait for, or we're in its replay call right
+ * now, so either way there's no point calling it again.
+ */
+ if (!dev->driver && dev->bus->dma_configure) {
+ mutex_unlock(&iommu_probe_device_lock);
+ dev->bus->dma_configure(dev);
+ mutex_lock(&iommu_probe_device_lock);
+ }
+ /*
+ * At this point, relevant devices either now have a fwspec which will
+ * match ops registered with a non-NULL fwnode, or we can reasonably
* assume that only one of Intel, AMD, s390, PAMU or legacy SMMUv2 can
* be present, and that any of their registered instances has suitable
* ops for probing, and thus cheekily co-opt the same mechanism.
@@ -426,6 +438,12 @@ static int iommu_init_device(struct device *dev)
ret = -ENODEV;
goto err_free;
}
+ /*
+ * And if we do now see any replay calls, they would indicate someone
+ * misusing the dma_configure path outside bus code.
+ */
+ if (dev->driver)
+ dev_WARN(dev, "late IOMMU probe at driver bind, something fishy here!\n");
if (!try_module_get(ops->owner)) {
ret = -EINVAL;
@@ -155,7 +155,12 @@ int of_iommu_configure(struct device *dev, struct device_node *master_np,
dev_iommu_free(dev);
mutex_unlock(&iommu_probe_device_lock);
- if (!err && dev->bus)
+ /*
+ * If we're not on the iommu_probe_device() path (as indicated by the
+ * initial dev->iommu) then try to simulate it. This should no longer
+ * happen unless of_dma_configure() is being misused outside bus code.
+ */
+ if (!err && dev->bus && !dev_iommu_present)
err = iommu_probe_device(dev);
if (err && err != -EPROBE_DEFER)
@@ -99,6 +99,11 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
bool coherent, set_map = false;
int ret;
+ if (dev->dma_range_map) {
+ dev_dbg(dev, "dma_range_map already set\n");
+ goto skip_map;
+ }
+
if (np == dev->of_node)
bus_np = __of_get_dma_parent(np);
else
@@ -119,7 +124,7 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
end = dma_range_map_max(map);
set_map = true;
}
-
+skip_map:
/*
* If @dev is expected to be DMA-capable then the bus code that created
* it should have initialised its dma_mask pointer by this point. For
@@ -1653,7 +1653,8 @@ static int pci_dma_configure(struct device *dev)
pci_put_host_bridge_device(bridge);
- if (!ret && !driver->driver_managed_dma) {
+ /* @driver may not be valid when we're called from the IOMMU layer */
+ if (!ret && dev->driver && !driver->driver_managed_dma) {
ret = iommu_device_use_default_domain(dev);
if (ret)
arch_teardown_dma_ops(dev);
In hindsight, there were some crucial subtleties overlooked when moving {of,acpi}_dma_configure() to driver probe time to allow waiting for IOMMU drivers with -EPROBE_DEFER, and these have become an ever-increasing source of problems. The IOMMU API has some fundamental assumptions that iommu_probe_device() is called for every device added to the system, in the order in which they are added. Calling it in a random order or not at all dependent on driver binding leads to malformed groups, a potential lack of isolation for devices with no driver, and all manner of unexpected concurrency and race conditions. We've attempted to mitigate the latter with point-fix bodges like iommu_probe_device_lock, but it's a losing battle and the time has come to bite the bullet and address the true source of the problem instead. The crux of the matter is that the firmware parsing actually serves two distinct purposes; one is identifying the IOMMU instance associated with a device so we can check its availability, the second is actually telling that instance about the relevant firmware-provided data for the device. However the latter also depends on the former, and at the time there was no good place to defer and retry that separately from the availability check we also wanted for client driver probe. Nowadays, though, we have a proper notion of multiple IOMMU instances in the core API itself, and each one gets a chance to probe its own devices upon registration, so we can finally make that work as intended for DT/IORT/VIOT platforms too. All we need is for iommu_probe_device() to be able to run the iommu_fwspec machinery currently buried deep in the wrong end of {of,acpi}_dma_configure(). Luckily it turns out to be surprisingly straightforward to bootstrap this transformation by pretty much just calling the same path twice. At client driver probe time, dev->driver is obviously set; conversely at device_add(), or a subsequent bus_iommu_probe(), any device waiting for an IOMMU really should *not* have a driver already, so we can use that as a condition to disambiguate the two cases, and avoid recursing back into the IOMMU core at the wrong times. Obviously this isn't the nicest thing, but for now it gives us a functional baseline to then unpick the layers in between without many more awkward cross-subsystem patches. There are some minor side-effects like dma_range_map potentially being created earlier, and some debug prints being repeated, but these aren't significantly detrimental. Let's make things work first, then deal with making them nice. With the basic flow finally in the right order again, the next step is probably turning the bus->dma_configure paths inside-out, since all we really need from bus code is its notion of which device and input ID(s) to parse the common firmware properties with... Acked-by: Bjorn Helgaas <bhelgaas@google.com> # pci-driver.c Acked-by: Rob Herring (Arm) <robh@kernel.org> # of/device.c Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- v2: - Comment bus driver changes for clarity - Use dev->iommu as the now-robust replay condition - Drop the device_iommu_mapped() checks in the firmware paths as they weren't doing much - we can't replace probe_device_lock just yet... drivers/acpi/arm64/dma.c | 5 +++++ drivers/acpi/scan.c | 7 ------- drivers/amba/bus.c | 3 ++- drivers/base/platform.c | 3 ++- drivers/bus/fsl-mc/fsl-mc-bus.c | 3 ++- drivers/cdx/cdx.c | 3 ++- drivers/iommu/iommu.c | 24 +++++++++++++++++++++--- drivers/iommu/of_iommu.c | 7 ++++++- drivers/of/device.c | 7 ++++++- drivers/pci/pci-driver.c | 3 ++- 10 files changed, 48 insertions(+), 17 deletions(-)