Otherwise an guest can subvert the generic MSI code to trigger
an BUG_ON condition during MSI interrupt freeing:
for (i = 0; i < entry->nvec_used; i++)
BUG_ON(irq_has_action(entry->irq + i));
Xen PCI backed installs an IRQ handler (request_irq) for
the dev->irq whenever the guest writes PCI_COMMAND_MEMORY
(or PCI_COMMAND_IO) to the PCI_COMMAND register. This is
done in case the device has legacy interrupts the GSI line
is shared by the backend devices.
To subvert the backend the guest needs to make the backend
to change the dev->irq from the GSI to the MSI interrupt line,
make the backend allocate an interrupt handler, and then command
the backend to free the MSI interrupt and hit the BUG_ON.
Since the backend only calls 'request_irq' when the guest
writes to the PCI_COMMAND register the guest needs to call
XEN_PCI_OP_enable_msi before any other operation. This will
cause the generic MSI code to setup an MSI entry and
populate dev->irq with the new PIRQ value.
Then the guest can write to PCI_COMMAND PCI_COMMAND_MEMORY
and cause the backend to setup an IRQ handler for dev->irq
(which instead of the GSI value has the MSI pirq). See
'xen_pcibk_control_isr'.
Then the guest disables the MSI: XEN_PCI_OP_disable_msi
which ends up triggering the BUG_ON condition in 'free_msi_irqs'
as there is an IRQ handler for the entry->irq (dev->irq).
Note that this cannot be done using MSI-X as the generic
code does not over-write dev->irq with the MSI-X PIRQ values.
The patch inhibits setting up the IRQ handler if MSI or
MSI-X (for symmetry reasons) code had been called successfully.
P.S.
Xen PCIBack when it sets up the device for the guest consumption
ends up writting 0 to the PCI_COMMAND (see xen_pcibk_reset_device).
XSA-120 addendum patch removed that - however when upstreaming said
addendum we found that it caused issues with qemu upstream. That
has now been fixed in qemu upstream.
This is part of XSA-157
CC: stable@vger.kernel.org
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The guest sequence of:
a) XEN_PCI_OP_enable_msix
b) XEN_PCI_OP_enable_msix
results in hitting an NULL pointer due to using freed pointers.
The device passed in the guest MUST have MSI-X capability.
The a) constructs and SysFS representation of MSI and MSI groups.
The b) adds a second set of them but adding in to SysFS fails (duplicate entry).
'populate_msi_sysfs' frees the newly allocated msi_irq_groups (note that
in a) pdev->msi_irq_groups is still set) and also free's ALL of the
MSI-X entries of the device (the ones allocated in step a) and b)).
The unwind code: 'free_msi_irqs' deletes all the entries and tries to
delete the pdev->msi_irq_groups (which hasn't been set to NULL).
However the pointers in the SysFS are already freed and we hit an
NULL pointer further on when 'strlen' is attempted on a freed pointer.
The patch adds a simple check in the XEN_PCI_OP_enable_msix to guard
against that. The check for msi_enabled is not stricly neccessary.
This is part of XSA-157
CC: stable@vger.kernel.org
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The guest sequence of:
a) XEN_PCI_OP_enable_msi
b) XEN_PCI_OP_enable_msi
c) XEN_PCI_OP_disable_msi
results in hitting an BUG_ON condition in the msi.c code.
The MSI code uses an dev->msi_list to which it adds MSI entries.
Under the above conditions an BUG_ON() can be hit. The device
passed in the guest MUST have MSI capability.
The a) adds the entry to the dev->msi_list and sets msi_enabled.
The b) adds a second entry but adding in to SysFS fails (duplicate entry)
and deletes all of the entries from msi_list and returns (with msi_enabled
is still set). c) pci_disable_msi passes the msi_enabled checks and hits:
BUG_ON(list_empty(dev_to_msi_list(&dev->dev)));
and blows up.
The patch adds a simple check in the XEN_PCI_OP_enable_msi to guard
against that. The check for msix_enabled is not stricly neccessary.
This is part of XSA-157.
CC: stable@vger.kernel.org
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Double fetch vulnerabilities that happen when a variable is
fetched twice from shared memory but a security check is only
performed the first time.
The xen_pcibk_do_op function performs a switch statements on the op->cmd
value which is stored in shared memory. Interestingly this can result
in a double fetch vulnerability depending on the performed compiler
optimization.
This patch fixes it by saving the xen_pci_op command before
processing it. We also use 'barrier' to make sure that the
compiler does not perform any optimization.
This is part of XSA155.
CC: stable@vger.kernel.org
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
There is a missing curly brace here so we might print some extra debug
information.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
As result of deprecation of MSI-X/MSI enablement functions
pci_enable_msix() and pci_enable_msi_block() all drivers
using these two interfaces need to be updated to use the
new pci_enable_msi_range() or pci_enable_msi_exact()
and pci_enable_msix_range() or pci_enable_msix_exact()
interfaces.
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: linux-pci@vger.kernel.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Convert printks to pr_<level> (excludes printk(KERN_DEBUG...)
to be more consistent throughout the xen subsystem.
Add pr_fmt with KBUILD_MODNAME or "xen:" KBUILD_MODNAME
Coalesce formats and add missing word spaces
Add missing newlines
Align arguments and reflow to 80 columns
Remove DRV_NAME from formats as pr_fmt adds the same content
This does change some of the prefixes of these messages
but it also does make them more consistent.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
... as being guest triggerable (e.g. by invoking
XEN_PCI_OP_enable_msi{,x} on a device not being MSI/MSI-X capable).
This is CVE-2013-0231 / XSA-43.
Also make the two messages uniform in both their wording and severity.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Prior to 2.6.19 and as of 2.6.31, pci_enable_msix() can return a
positive value to indicate the number of vectors (less than the amount
requested) that can be set up for a given device. Returning this as an
operation value (secondary result) is fine, but (primary) operation
results are expected to be negative (error) or zero (success) according
to the protocol. With the frontend fixed to match the XenoLinux
behavior, the backend can now validly return zero (success) here,
passing the upper limit on the number of vectors in op->value.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This is a minor bugfix and a set of small cleanups; as it is not clear
whether this needs splitting into pieces (and if so, at what
granularity), it is a single combined patch.
- add a missing return statement to an error path in
kill_domain_by_device()
- use pci_is_enabled() rather than raw atomic_read()
- remove a bogus attempt to zero-terminate an already zero-terminated
string
- #define DRV_NAME once uniformly in the shared local header
- make DRIVER_ATTR() variables static
- eliminate a pointless use of list_for_each_entry_safe()
- add MODULE_ALIAS()
- a little bit of constification
- adjust a few messages
- remove stray semicolons from inline function definitions
Signed-off-by: Jan Beulich <jbeulich@suse.com>
[v1: Dropped the resource_size fix, altered the description]
[v2: Fixed cleanpatch.pl comments]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
- Remove the slot and controller controller backend as they
are not used.
- Document the find pciback_[read|write]_config_[byte|word|dword]
to make it easier to find.
- Collapse the code from conf_space_capability_msi into pciback_ops.c
- Collapse conf_space_capability_[pm|vpd].c in conf_space_capability.c
[and remove the conf_space_capability.h file]
- Rename all visible functions from pciback to xen_pcibk.
- Rename all the printk/pr_info, etc that use the "pciback" to say
"xen-pciback".
- Convert functions that are not referenced outside the code to be
static to save on name space.
- Do the same thing for structures that are internal to the driver.
- Run checkpatch.pl after the renames and fixup its warnings and
fix any compile errors caused by the variable rename
- Cleanup any structs that checkpath.pl commented about or just
look odd.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
If we try to setup an fake IRQ handler for legacy interrupts
for devices that only have MSI-X (most if not all SR-IOV cards),
we will fail with this:
pciback[0000:01:10.0]: failed to install fake IRQ handler for IRQ 0! (rc:-38)
Since those cards don't have anything in dev->irq.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
If the device that is to be shared with a guest is a level device and
the IRQ is shared with the initial domain we need to take actions.
Mainly we install a dummy IRQ handler that will ACK on the interrupt
line so as to not have the initial domain disable the interrupt line.
This dummy IRQ handler is not enabled when the device MSI/MSI-X lines
are set, nor for edge interrupts. And also not for level interrupts
that are not shared amongst devices. Lastly, if the user passes
to the guest all of the PCI devices on the shared line the we won't
install the dummy handler either.
There is also SysFS instrumentation to check its state and turn
IRQ ACKing on/off if necessary.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
In cases where the guest is abruptly killed and has not disabled
MSI/MSI-X interrupts we want to do it for it.
Otherwise when the guest is started up and enables MSI, we would
get a WARN() that the device already had been enabled.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This is the host side counterpart to the frontend driver in
drivers/pci/xen-pcifront.c. The PV protocol is also implemented by
frontend drivers in other OSes too, such as the BSDs.
The PV protocol is rather simple. There is page shared with the guest,
which has the 'struct xen_pci_sharedinfo' embossed in it. The backend
has a thread that is kicked every-time the structure is changed and
based on the operation field it performs specific tasks:
XEN_PCI_OP_conf_[read|write]:
Read/Write 0xCF8/0xCFC filtered data. (conf_space*.c)
Based on which field is probed, we either enable/disable the PCI
device, change power state, read VPD, etc. The major goal of this
call is to provide a Physical IRQ (PIRQ) to the guest.
The PIRQ is Xen hypervisor global IRQ value irrespective of the IRQ
is tied in to the IO-APIC, or is a vector. For GSI type
interrupts, the PIRQ==GSI holds. For MSI/MSI-X the
PIRQ value != Linux IRQ number (thought PIRQ==vector).
Please note, that with Xen, all interrupts (except those level shared ones)
are injected directly to the guest - there is no host interaction.
XEN_PCI_OP_[enable|disable]_msi[|x] (pciback_ops.c)
Enables/disables the MSI/MSI-X capability of the device. These operations
setup the MSI/MSI-X vectors for the guest and pass them to the frontend.
When the device is activated, the interrupts are directly injected in the
guest without involving the host.
XEN_PCI_OP_aer_[detected|resume|mmio|slotreset]: In case of failure,
perform the appropriate AER commands on the guest. Right now that is
a cop-out - we just kill the guest.
Besides implementing those commands, it can also
- hide a PCI device from the host. When booting up, the user can specify
xen-pciback.hide=(1:0:0)(BDF..) so that host does not try to use the
device.
The driver was lifted from linux-2.6.18.hg tree and fixed up
so that it could compile under v3.0. Per suggestion from Jesse Barnes
moved the driver to drivers/xen/xen-pciback.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
