On Wed, Feb 01, 2012 at 03:46:52PM +1100, David Gibson wrote: > In order to safely drive a device with a userspace driver, or to pass > it through to a guest system, we must first make sure that the device > is isolated in such a way that it cannot interfere with other devices > on the system. This isolation is only available on some systems and > will generally require an iommu, and might require other support in > bridges or other system hardware. > > Often, it's not possible to isolate every device from every other > device in the system. For example, certain PCI/PCIe bridge > configurations mean that an iommu cannot reliably distinguish which > device behind the bridge initiated a DMA transaction. Similarly some > buggy PCI multifunction devices initiate all DMAs as function 0, so > the functions cannot be isolated from each other, even if the IOMMU > normally allows this. > > Therefore, the user, and code to allow userspace drivers or guest > passthrough, needs a way to determine which devices can be isolated > from which others. This patch adds infrastructure to handle this by > introducing the concept of a "device isolation group" - a group of > devices which can, as a unit, be safely isolated from the rest of the > system and therefore can be, as a unit, safely assigned to an > unprivileged used or guest. That is, the groups represent the minimum > granularity with which devices may be assigned to untrusted > components. > > This code manages groups, but does not create them or allow use of > grouped devices by a guest. Creating groups would be done by iommu or > bridge drivers, using the interface this patch provides. It's > expected that the groups will be used in future by the in-kernel iommu > interface, and would also be used by VFIO or other subsystems to allow > safe passthrough of devices to userspace or guests. > > Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx> > Signed-off-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> > --- > drivers/base/Kconfig | 3 + > drivers/base/Makefile | 1 + > drivers/base/base.h | 3 + > drivers/base/core.c | 6 ++ > drivers/base/device_isolation.c | 184 ++++++++++++++++++++++++++++++++++++++ > drivers/base/init.c | 2 + > include/linux/device.h | 5 + > include/linux/device_isolation.h | 100 +++++++++++++++++++++ Again, device grouping is done by the IOMMU drivers, so this all belongs into the generic iommu-code rather than the driver core. I think it makes sense to introduce a device->iommu pointer which depends on CONFIG_IOMMU_API and put the group information into it. This also has the benefit that we can consolidate all the device->arch.iommu pointers into device->iommu as well. > 8 files changed, 304 insertions(+), 0 deletions(-) > create mode 100644 drivers/base/device_isolation.c > create mode 100644 include/linux/device_isolation.h > > diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig > index 7be9f79..a52f2db 100644 > --- a/drivers/base/Kconfig > +++ b/drivers/base/Kconfig > @@ -189,4 +189,7 @@ config DMA_SHARED_BUFFER > APIs extension; the file's descriptor can then be passed on to other > driver. > > +config DEVICE_ISOLATION > + bool "Enable isolating devices for safe pass-through to guests or user space." > + No need for a config option. When IOMMU drivers are enabled we also want the group code to be active. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
