linux.git/drivers/vfio, branch v4.14.149

vfio_pci: Restore original state on release

2019-10-07T16:55:03+00:00

[ Upstream commit 92c8026854c25093946e0d7fe536fd9eac440f06 ]

vfio_pci_enable() saves the device's initial configuration information
with the intent that it is restored in vfio_pci_disable().  However,
the commit referenced in Fixes: below replaced the call to
__pci_reset_function_locked(), which is not wrapped in a state save
and restore, with pci_try_reset_function(), which overwrites the
restored device state with the current state before applying it to the
device.  Reinstate use of __pci_reset_function_locked() to return to
the desired behavior.

Fixes: 890ed578df82 ("vfio-pci: Use pci "try" reset interface")
Signed-off-by: hexin 
Signed-off-by: Liu Qi 
Signed-off-by: Zhang Yu 
Signed-off-by: Alex Williamson 
Signed-off-by: Sasha Levin

vfio: Fix WARNING "do not call blocking ops when !TASK_RUNNING"

2019-06-15T09:54:54+00:00

[ Upstream commit 41be3e2618174fdf3361e49e64f2bf530f40c6b0 ]

vfio_dev_present() which is the condition to
wait_event_interruptible_timeout(), will call vfio_group_get_device
and try to acquire the mutex group->device_lock.

wait_event_interruptible_timeout() will set the state of the current
task to TASK_INTERRUPTIBLE, before doing the condition check. This
means that we will try to acquire the mutex while already in a
sleeping state. The scheduler warns us by giving the following
warning:

[ 4050.264464] ------------[ cut here ]------------
[ 4050.264508] do not call blocking ops when !TASK_RUNNING; state=1 set at [<00000000b33c00e2>] prepare_to_wait_event+0x14a/0x188
[ 4050.264529] WARNING: CPU: 12 PID: 35924 at kernel/sched/core.c:6112 __might_sleep+0x76/0x90
....

 4050.264756] Call Trace:
[ 4050.264765] ([<000000000017bbaa>] __might_sleep+0x72/0x90)
[ 4050.264774]  [<0000000000b97edc>] __mutex_lock+0x44/0x8c0
[ 4050.264782]  [<0000000000b9878a>] mutex_lock_nested+0x32/0x40
[ 4050.264793]  [<000003ff800d7abe>] vfio_group_get_device+0x36/0xa8 [vfio]
[ 4050.264803]  [<000003ff800d87c0>] vfio_del_group_dev+0x238/0x378 [vfio]
[ 4050.264813]  [<000003ff8015f67c>] mdev_remove+0x3c/0x68 [mdev]
[ 4050.264825]  [<00000000008e01b0>] device_release_driver_internal+0x168/0x268
[ 4050.264834]  [<00000000008de692>] bus_remove_device+0x162/0x190
[ 4050.264843]  [<00000000008daf42>] device_del+0x1e2/0x368
[ 4050.264851]  [<00000000008db12c>] device_unregister+0x64/0x88
[ 4050.264862]  [<000003ff8015ed84>] mdev_device_remove+0xec/0x130 [mdev]
[ 4050.264872]  [<000003ff8015f074>] remove_store+0x6c/0xa8 [mdev]
[ 4050.264881]  [<000000000046f494>] kernfs_fop_write+0x14c/0x1f8
[ 4050.264890]  [<00000000003c1530>] __vfs_write+0x38/0x1a8
[ 4050.264899]  [<00000000003c187c>] vfs_write+0xb4/0x198
[ 4050.264908]  [<00000000003c1af2>] ksys_write+0x5a/0xb0
[ 4050.264916]  [<0000000000b9e270>] system_call+0xdc/0x2d8
[ 4050.264925] 4 locks held by sh/35924:
[ 4050.264933]  #0: 000000001ef90325 (sb_writers#4){.+.+}, at: vfs_write+0x9e/0x198
[ 4050.264948]  #1: 000000005c1ab0b3 (&of->mutex){+.+.}, at: kernfs_fop_write+0x1cc/0x1f8
[ 4050.264963]  #2: 0000000034831ab8 (kn->count#297){++++}, at: kernfs_remove_self+0x12e/0x150
[ 4050.264979]  #3: 00000000e152484f (&dev->mutex){....}, at: device_release_driver_internal+0x5c/0x268
[ 4050.264993] Last Breaking-Event-Address:
[ 4050.265002]  [<000000000017bbaa>] __might_sleep+0x72/0x90
[ 4050.265010] irq event stamp: 7039
[ 4050.265020] hardirqs last  enabled at (7047): [<00000000001cee7a>] console_unlock+0x6d2/0x740
[ 4050.265029] hardirqs last disabled at (7054): [<00000000001ce87e>] console_unlock+0xd6/0x740
[ 4050.265040] softirqs last  enabled at (6416): [<0000000000b8fe26>] __udelay+0xb6/0x100
[ 4050.265049] softirqs last disabled at (6415): [<0000000000b8fe06>] __udelay+0x96/0x100
[ 4050.265057] ---[ end trace d04a07d39d99a9f9 ]---

Let's fix this as described in the article
https://lwn.net/Articles/628628/.

Signed-off-by: Farhan Ali 
[remove now redundant vfio_dev_present()]
Signed-off-by: Alex Williamson 
Signed-off-by: Sasha Levin

vfio/pci: use correct format characters

2019-05-08T05:20:49+00:00

[ Upstream commit 426b046b748d1f47e096e05bdcc6fb4172791307 ]

When compiling with -Wformat, clang emits the following warnings:

drivers/vfio/pci/vfio_pci.c:1601:5: warning: format specifies type
      'unsigned short' but the argument has type 'unsigned int' [-Wformat]
                                vendor, device, subvendor, subdevice,
                                ^~~~~~

drivers/vfio/pci/vfio_pci.c:1601:13: warning: format specifies type
      'unsigned short' but the argument has type 'unsigned int' [-Wformat]
                                vendor, device, subvendor, subdevice,
                                        ^~~~~~

drivers/vfio/pci/vfio_pci.c:1601:21: warning: format specifies type
      'unsigned short' but the argument has type 'unsigned int' [-Wformat]
                                vendor, device, subvendor, subdevice,
                                                ^~~~~~~~~

drivers/vfio/pci/vfio_pci.c:1601:32: warning: format specifies type
      'unsigned short' but the argument has type 'unsigned int' [-Wformat]
                                vendor, device, subvendor, subdevice,
                                                           ^~~~~~~~~

drivers/vfio/pci/vfio_pci.c:1605:5: warning: format specifies type
      'unsigned short' but the argument has type 'unsigned int' [-Wformat]
                                vendor, device, subvendor, subdevice,
                                ^~~~~~

drivers/vfio/pci/vfio_pci.c:1605:13: warning: format specifies type
      'unsigned short' but the argument has type 'unsigned int' [-Wformat]
                                vendor, device, subvendor, subdevice,
                                        ^~~~~~

drivers/vfio/pci/vfio_pci.c:1605:21: warning: format specifies type
      'unsigned short' but the argument has type 'unsigned int' [-Wformat]
                                vendor, device, subvendor, subdevice,
                                                ^~~~~~~~~

drivers/vfio/pci/vfio_pci.c:1605:32: warning: format specifies type
      'unsigned short' but the argument has type 'unsigned int' [-Wformat]
                                vendor, device, subvendor, subdevice,
                                                           ^~~~~~~~~
The types of these arguments are unconditionally defined, so this patch
updates the format character to the correct ones for unsigned ints.

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Signed-off-by: Louis Taylor 
Reviewed-by: Nick Desaulniers 
Signed-off-by: Alex Williamson 
Signed-off-by: Sasha Levin

vfio/type1: Limit DMA mappings per container

2019-05-02T07:40:30+00:00

commit 492855939bdb59c6f947b0b5b44af9ad82b7e38c upstream.

Memory backed DMA mappings are accounted against a user's locked
memory limit, including multiple mappings of the same memory.  This
accounting bounds the number of such mappings that a user can create.
However, DMA mappings that are not backed by memory, such as DMA
mappings of device MMIO via mmaps, do not make use of page pinning
and therefore do not count against the user's locked memory limit.
These mappings still consume memory, but the memory is not well
associated to the process for the purpose of oom killing a task.

To add bounding on this use case, we introduce a limit to the total
number of concurrent DMA mappings that a user is allowed to create.
This limit is exposed as a tunable module option where the default
value of 64K is expected to be well in excess of any reasonable use
case (a large virtual machine configuration would typically only make
use of tens of concurrent mappings).

This fixes CVE-2019-3882.

Reviewed-by: Eric Auger 
Tested-by: Eric Auger 
Reviewed-by: Peter Xu 
Reviewed-by: Cornelia Huck 
Signed-off-by: Alex Williamson 
Signed-off-by: Greg Kroah-Hartman

vfio/type1: Fix task tracking for QEMU vCPU hotplug

2018-08-03T05:50:23+00:00

[ Upstream commit 48d8476b41eed63567dd2f0ad125c895b9ac648a ]

MAP_DMA ioctls might be called from various threads within a process,
for example when using QEMU, the vCPU threads are often generating
these calls and we therefore take a reference to that vCPU task.
However, QEMU also supports vCPU hotplug on some machines and the task
that called MAP_DMA may have exited by the time UNMAP_DMA is called,
resulting in the mm_struct pointer being NULL and thus a failure to
match against the existing mapping.

To resolve this, we instead take a reference to the thread
group_leader, which has the same mm_struct and resource limits, but
is less likely exit, at least in the QEMU case.  A difficulty here is
guaranteeing that the capabilities of the group_leader match that of
the calling thread, which we resolve by tracking CAP_IPC_LOCK at the
time of calling rather than at an indeterminate time in the future.
Potentially this also results in better efficiency as this is now
recorded once per MAP_DMA ioctl.

Reported-by: Xu Yandong 
Signed-off-by: Alex Williamson 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

vfio/mdev: Check globally for duplicate devices

2018-08-03T05:50:22+00:00

[ Upstream commit 002fe996f67f4f46d8917b14cfb6e4313c20685a ]

When we create an mdev device, we check for duplicates against the
parent device and return -EEXIST if found, but the mdev device
namespace is global since we'll link all devices from the bus.  We do
catch this later in sysfs_do_create_link_sd() to return -EEXIST, but
with it comes a kernel warning and stack trace for trying to create
duplicate sysfs links, which makes it an undesirable response.

Therefore we should really be looking for duplicates across all mdev
parent devices, or as implemented here, against our mdev device list.
Using mdev_list to prevent duplicates means that we can remove
mdev_parent.lock, but in order not to serialize mdev device creation
and removal globally, we add mdev_device.active which allows UUIDs to
be reserved such that we can drop the mdev_list_lock before the mdev
device is fully in place.

Two behavioral notes; first, mdev_parent.lock had the side-effect of
serializing mdev create and remove ops per parent device.  This was
an implementation detail, not an intentional guarantee provided to
the mdev vendor drivers.  Vendor drivers can trivially provide this
serialization internally if necessary.  Second, review comments note
the new -EAGAIN behavior when the device, and in particular the remove
attribute, becomes visible in sysfs.  If a remove is triggered prior
to completion of mdev_device_create() the user will see a -EAGAIN
error.  While the errno is different, receiving an error during this
period is not, the previous implementation returned -ENODEV for the
same condition.  Furthermore, the consistency to the user is improved
in the case where mdev_device_remove_ops() returns error.  Previously
concurrent calls to mdev_device_remove() could see the device
disappear with -ENODEV and return in the case of error.  Now a user
would see -EAGAIN while the device is in this transitory state.

Reviewed-by: Kirti Wankhede 
Reviewed-by: Cornelia Huck 
Acked-by: Halil Pasic 
Acked-by: Zhenyu Wang 
Signed-off-by: Alex Williamson 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

vfio: platform: Fix reset module leak in error path

2018-08-03T05:50:22+00:00

[ Upstream commit 28a68387888997e8a7fa57940ea5d55f2e16b594 ]

If the IOMMU group setup fails, the reset module is not released.

Fixes: b5add544d677d363 ("vfio, platform: make reset driver a requirement by default")
Signed-off-by: Geert Uytterhoeven 
Reviewed-by: Eric Auger 
Reviewed-by: Simon Horman 
Acked-by: Eric Auger 
Signed-off-by: Alex Williamson 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

KVM: PPC: Check if IOMMU page is contained in the pinned physical page

2018-07-28T05:55:41+00:00

commit 76fa4975f3ed12d15762bc979ca44078598ed8ee upstream.

A VM which has:
 - a DMA capable device passed through to it (eg. network card);
 - running a malicious kernel that ignores H_PUT_TCE failure;
 - capability of using IOMMU pages bigger that physical pages
can create an IOMMU mapping that exposes (for example) 16MB of
the host physical memory to the device when only 64K was allocated to the VM.

The remaining 16MB - 64K will be some other content of host memory, possibly
including pages of the VM, but also pages of host kernel memory, host
programs or other VMs.

The attacking VM does not control the location of the page it can map,
and is only allowed to map as many pages as it has pages of RAM.

We already have a check in drivers/vfio/vfio_iommu_spapr_tce.c that
an IOMMU page is contained in the physical page so the PCI hardware won't
get access to unassigned host memory; however this check is missing in
the KVM fastpath (H_PUT_TCE accelerated code). We were lucky so far and
did not hit this yet as the very first time when the mapping happens
we do not have tbl::it_userspace allocated yet and fall back to
the userspace which in turn calls VFIO IOMMU driver, this fails and
the guest does not retry,

This stores the smallest preregistered page size in the preregistered
region descriptor and changes the mm_iommu_xxx API to check this against
the IOMMU page size.

This calculates maximum page size as a minimum of the natural region
alignment and compound page size. For the page shift this uses the shift
returned by find_linux_pte() which indicates how the page is mapped to
the current userspace - if the page is huge and this is not a zero, then
it is a leaf pte and the page is mapped within the range.

Fixes: 121f80ba68f1 ("KVM: PPC: VFIO: Add in-kernel acceleration for VFIO")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Alexey Kardashevskiy 
Reviewed-by: David Gibson 
Signed-off-by: Michael Ellerman 
Signed-off-by: Alexey Kardashevskiy 
Signed-off-by: Greg Kroah-Hartman

vfio/spapr: Use IOMMU pageshift rather than pagesize

2018-07-25T09:25:08+00:00

commit 1463edca6734d42ab4406fa2896e20b45478ea36 upstream.

The size is always equal to 1 page so let's use this. Later on this will
be used for other checks which use page shifts to check the granularity
of access.

This should cause no behavioral change.

Cc: stable@vger.kernel.org # v4.12+
Reviewed-by: David Gibson 
Acked-by: Alex Williamson 
Signed-off-by: Alexey Kardashevskiy 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

vfio/pci: Fix potential Spectre v1

2018-07-25T09:25:08+00:00

commit 0e714d27786ce1fb3efa9aac58abc096e68b1c2a upstream.

info.index can be indirectly controlled by user-space, hence leading
to a potential exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:

drivers/vfio/pci/vfio_pci.c:734 vfio_pci_ioctl()
warn: potential spectre issue 'vdev->region'

Fix this by sanitizing info.index before indirectly using it to index
vdev->region

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva 
Signed-off-by: Alex Williamson 
Signed-off-by: Greg Kroah-Hartman