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authorLu Baolu <baolu.lu@linux.intel.com>2022-04-18 08:49:53 +0800
committerJoerg Roedel <jroedel@suse.de>2022-04-28 15:32:20 +0200
commit512881eacfa72c2136b27b9934b7b27504a9efc2 (patch)
tree6d4777d18fa5d0d753f67678f52aa158696580e9 /drivers/amba
parent4a6d9dd564d0e7339fc15ecc5ce66db4ad842be2 (diff)
downloadlwn-512881eacfa72c2136b27b9934b7b27504a9efc2.tar.gz
lwn-512881eacfa72c2136b27b9934b7b27504a9efc2.zip
bus: platform,amba,fsl-mc,PCI: Add device DMA ownership management
The devices on platform/amba/fsl-mc/PCI buses could be bound to drivers with the device DMA managed by kernel drivers or user-space applications. Unfortunately, multiple devices may be placed in the same IOMMU group because they cannot be isolated from each other. The DMA on these devices must either be entirely under kernel control or userspace control, never a mixture. Otherwise the driver integrity is not guaranteed because they could access each other through the peer-to-peer accesses which by-pass the IOMMU protection. This checks and sets the default DMA mode during driver binding, and cleanups during driver unbinding. In the default mode, the device DMA is managed by the device driver which handles DMA operations through the kernel DMA APIs (see Documentation/core-api/dma-api.rst). For cases where the devices are assigned for userspace control through the userspace driver framework(i.e. VFIO), the drivers(for example, vfio_pci/ vfio_platfrom etc.) may set a new flag (driver_managed_dma) to skip this default setting in the assumption that the drivers know what they are doing with the device DMA. Calling iommu_device_use_default_domain() before {of,acpi}_dma_configure is currently a problem. As things stand, the IOMMU driver ignored the initial iommu_probe_device() call when the device was added, since at that point it had no fwspec yet. In this situation, {of,acpi}_iommu_configure() are retriggering iommu_probe_device() after the IOMMU driver has seen the firmware data via .of_xlate to learn that it actually responsible for the given device. As the result, before that gets fixed, iommu_use_default_domain() goes at the end, and calls arch_teardown_dma_ops() if it fails. Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Stuart Yoder <stuyoder@gmail.com> Cc: Laurentiu Tudor <laurentiu.tudor@nxp.com> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Tested-by: Eric Auger <eric.auger@redhat.com> Link: https://lore.kernel.org/r/20220418005000.897664-5-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/amba')
-rw-r--r--drivers/amba/bus.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 76b52bd2c2a4..a0ec61232b6c 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -22,6 +22,8 @@
#include <linux/of_irq.h>
#include <linux/of_device.h>
#include <linux/acpi.h>
+#include <linux/iommu.h>
+#include <linux/dma-map-ops.h>
#define to_amba_driver(d) container_of(d, struct amba_driver, drv)
@@ -277,6 +279,7 @@ static void amba_shutdown(struct device *dev)
static int amba_dma_configure(struct device *dev)
{
+ struct amba_driver *drv = to_amba_driver(dev->driver);
enum dev_dma_attr attr;
int ret = 0;
@@ -287,9 +290,23 @@ static int amba_dma_configure(struct device *dev)
ret = acpi_dma_configure(dev, attr);
}
+ if (!ret && !drv->driver_managed_dma) {
+ ret = iommu_device_use_default_domain(dev);
+ if (ret)
+ arch_teardown_dma_ops(dev);
+ }
+
return ret;
}
+static void amba_dma_cleanup(struct device *dev)
+{
+ struct amba_driver *drv = to_amba_driver(dev->driver);
+
+ if (!drv->driver_managed_dma)
+ iommu_device_unuse_default_domain(dev);
+}
+
#ifdef CONFIG_PM
/*
* Hooks to provide runtime PM of the pclk (bus clock). It is safe to
@@ -359,6 +376,7 @@ struct bus_type amba_bustype = {
.remove = amba_remove,
.shutdown = amba_shutdown,
.dma_configure = amba_dma_configure,
+ .dma_cleanup = amba_dma_cleanup,
.pm = &amba_pm,
};
EXPORT_SYMBOL_GPL(amba_bustype);