Add pvcalls support to libxl and xl. Create the appropriate pvcalls
entries in xenstore.
Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
All this information is now covered in SUPPORT.md.
Most of the emulated hardware is obvious a couple of the items are
worth pointing out specifically.
"xen_disk" is listed under "Blkback"
"...the PCI host bridge and the PIIX3 chipset...": This statement is
redundant -- the PCI host bridge is a part of the piix3 chipset, which
is listed as supported.
xenfb: The "graphics" side of "xenfb" is listed under "PV Framebuffer
(backend)", and the "input" side of "xenfb" (including both keyboard
and mouse) is listed under "PV Keyboard (backend)".
Backing storage image format is listed in the "Blkback" section.
Fix 'stdvga' spelling while we're here.
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Xen does not properly support big.LITTLE platform. All vCPUs of a guest
will always have the MIDR of the boot CPU (see arch_domain_create).
At best the guest may see unreliable performance (vCPU switching between
big and LITTLE), at worst the guest will become unreliable or insecure.
This is becoming more apparent with branch predictor hardening in Linux
because they target a specific kind of CPUs and may not work on other
CPUs.
For the time being, park any CPUs with a MDIR different from the boot
CPU. This will be revisited in the future once Xen gains understanding
of big.LITTLE.
[1] https://lists.xenproject.org/archives/html/xen-devel/2016-12/msg00826.html
Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Oleksandr Tyshchenkko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
This patch was originally released as part of XSA-226. It retains the same
command line syntax (as various downstreams are mitigating XSA-226 using this
mechanism) but the defaults have been updated due to the revised XSA-226
patched, after which transitive grants are believed to functioning
properly.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
The current XPTI implementation isolates the directmap (and therefore a lot of
guest data), but a large quantity of CPU0's state (including its stack)
remains visible.
Furthermore, an attacker able to read .text is in a vastly superior position
to normal when it comes to fingerprinting Xen for known vulnerabilities, or
scanning for ROP/Spectre gadgets.
Collect together the entrypoints in .text.entry (currently 3x4k frames, but
can almost certainly be slimmed down), and create a common mapping which is
inserted into each per-cpu shadow. The stubs are also inserted into this
mapping by pointing at the in-use L2. This allows stubs allocated later (SMP
boot, or CPU hotplug) to work without further changes to the common mappings.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
So it can be used by both gcc and clang. Just add the Kconfig option
and modify the makefiles so the llvm coverage specific code can be
added in a follow up patch.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
[jb: also change the shim config]
Support both a "disable everything" and a "disable all RSB overwriting"
sub-option.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Issuing an IBPB command flushes the Branch Target Buffer, so that any poison
left by one vcpu won't remain when beginning to execute the next.
The cost of IBPB is substantial, and skipped on transition to idle, as Xen's
idle code is robust already. All transitions into vcpu context are fully
serialising in practice (and under consideration for being retroactively
declared architecturally serialising), so a cunning attacker cannot use SP1 to
try and skip the flush.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
See the logic and comments in init_speculation_mitigations() for further
details.
There are two controls for RSB overwriting, because in principle there are
cases where it might be safe to forego rsb_native (Off the top of my head,
SMEP active, no 32bit PV guests at all, no use of vmevent/paging subsystems
for HVM guests, but I make no guarantees that this list of restrictions is
exhaustive).
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
shim_mem will now account for both the memory used by the hypervisor
loaded in memory and the free memory slack given to the shim for
runtime usage.
From experimental testing it seems like the total amount of MiB used
by the shim (giving it ~1MB of free memory for runtime) is:
memory/113 + 20
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Instead of gaining yet another top level boolean, introduce a more generic
cpuid= option. Also introduce a helper function to parse a generic boolean
value.
This is part of XSA-254.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Depending on hardware and microcode availability, we will want to replace
IND_THUNK_REPOLINE with other implementations.
For AMD hardware, choose IND_THUNK_LFENCE in preference to retpoline if lfence
is known to be (or was successfully made) dispatch serialising.
This is part of XSA-254.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
First of all we don't need it on AMD systems. Additionally allow its use
to be controlled by command line option. For best backportability, this
intentionally doesn't use alternative instruction patching to achieve
the intended effect - while we likely want it, this will be later
follow-up.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Allowing pagetables to point to other pagetables of the same level
(often called 'linear pagetables') has been included in Xen since its
inception; but recently it has been the source of a number of subtle
reference-counting bugs.
It is not used by Linux or MiniOS; but it is used by NetBSD and Novell
Netware. There are significant numbers of people who are never going
to use the feature, along with significant numbers who need the
feature.
Add a Kconfig option for the feature (default to 'y'). Also add a
command-line option to control whether PV linear pagetables are
allowed (default to 'true').
NB that we leave linear_pt_count in the page struct. It's in a union,
so its presence doesn't increase the size of the data struct.
Changing the layout of the other elements based on configuration
options is asking for trouble however; so we'll just leave it there
and ASSERT that it's zero.
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Julien Grall <julien.grall@arm.com>
Make it possible for the user to specify, with the boot
time parameter rcu-idle-timer-period-ms, how frequently
a CPU that went idle with pending RCU callbacks should be
woken up to check if the grace period ended.
Typical values (i.e., some of the values used by Linux as
the tick frequency) are 10, 4 or 1 ms. Default valus (used
when this parameter is not specified) is 10ms. Maximum is
100ms.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Instead of using the same global resource limits of grant tables (max.
number of grant frames, max. number of maptrack frames) for all domains
make these limits per domain. Set those per-domain limits in
grant_table_set_limits(). The global settings are serving as an upper
boundary now which must not be exceeded by a per-domain value. The
default of max_grant_frames is set to the maximum default xl will use.
While updating the semantics of the boot parameters remove the
documentation of the no longer existing gnttab_max_nr_frames and
correct the default gnttab_max_maptrack_frames uses.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com> [non-ARM parts]
Acked-by: Julien Grall <julien.grall@arm.com>
Support modifying conswitch, console_timestamps, loglvl and
guest_loglvl at runtime.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Allow setting system enclosure asset tag for HVM guest. Guest OS can
check and perform desired operation like support installation.
Also added documentation of '~/bios-string/*' xenstore keys into
docs/misc/xenstore-paths.markdown
Signed-off-by: Vivek Kumar Chaubey <vivekkumar.chaubey@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
The way the lock is currently being used in get_maptrack_handle(), it
protects only the maptrack limit: The function acts on current's list
only, so races on list accesses are impossible even without the lock.
Otoh list access races are possible between __get_maptrack_handle() and
put_maptrack_handle(), due to the invocation of the former for other
than current from steal_maptrack_handle(). Introduce a per-vCPU lock
for list accesses to become race free again. This lock will be
uncontended except when it becomes necessary to take the steal path,
i.e. in the common case there should be no meaningful performance
impact.
When in get_maptrack_handle adds a stolen entry to a fresh, empty,
freelist, we think that there is probably no concurrency. However,
this is not a fast path and adding the locking there makes the code
clearly correct.
Also, while we are here: the stolen maptrack_entry's tail pointer was
not properly set. Set it.
This is CVE-2017-12136 / XSA-228.
Reported-by: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Delete the user visible option and code for PV superpage support. The
mm code is modified as if the option is set to false (the default
value).
Return the address space occupied by spage_info back to the reserved
address space.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The patch introduces a new command line option 'cpu' that when used will create
runqueue per logical pCPU. This may be useful for small systems, and also for
development, performance evalution and comparison.
Signed-off-by: Praveen Kumar <kpraveen.lkml@gmail.com>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
Add a warning: use passthrough with care.
Add a pointer to the gic device tree bindings. Add an explanation on how
to calculate irq numbers from device tree.
Add a brief explanation of the reg property and a pointer to the xl docs
for a description of the iomem property. Add a note that in the example
we are using different memory addresses for guests and host.
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Julien Grall <julien.grall@arm.com>
kexec: Provide user friendly option for memory limit
grub2 requires that the '<' character be escaped which is
inconvienet for users, provide a more natural specifier.
Signed-off-by: Simon Crowe <Simon.Crowe@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
The current misc/pvh.markdown document refers to PVHv1, remove it to
avoid confusion with PVHv2 since the PVHv1 code has already been
removed.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
iommu_inclusive_mapping is enabled by default (and has been for a long time).
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Also "correct" -> "incorrect" in the text.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
The ARM GICv3 provides a new kind of interrupt called LPIs.
The pending bits and the configuration data (priority, enable bits) for
those LPIs are stored in tables in normal memory, which software has to
provide to the hardware.
Allocate the required memory, initialize it and hand it over to each
redistributor. The maximum number of LPIs to be used can be adjusted with
the command line option "max_lpi_bits", which defaults to 20 bits,
covering about one million LPIs.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>
In cases where one is absolutely sure that there will be
less vCPUs than pCPUs, having to pay the cost, mostly in
terms of overhead, of an advanced scheduler may be not
desirable.
The simple scheduler implemented here could be a solution.
Here how it works:
- each vCPU is statically assigned to a pCPU;
- if there are pCPUs without any vCPU assigned, they
stay idle (as in, the run their idle vCPU);
- if there are vCPUs which are not assigned to any
pCPU (e.g., because there are more vCPUs than pCPUs)
they *don't* run, until they get assigned;
- if a vCPU assigned to a pCPU goes away, one of the
waiting to be assigned vCPU, if any, gets assigned
to the pCPU and can run there.
This scheduler, therefore, if used in configurations
where every vCPUs can be assigned to a pCPU, guarantees
low overhead, low latency, and consistent performance.
If used as default scheduler, at Xen boot, it is
recommended to limit the number of Dom0 vCPUs (e.g., with
'dom0_max_vcpus=x'). Otherwise, all the pCPUs will have
one Dom0's vCPU assigned, and there won't be room for
running efficiently (if at all) any guest.
Target use cases are embedded and HPC, but it may well
be interesting also in circumnstances.
Kconfig and documentation are update accordingly.
While there, also document the availability of sched=rtds
as boot parameter, which apparently had been forgotten.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
In order to distinguish guest-generated SErrors from hypervisor-generated
SErrors we have to place SError checking code in every EL1 <-> EL2 paths.
That will cause overhead on entries and exits due to dsb/isb.
However, not all platforms want to categorize SErrors. For example, a host
that is running with trusted guests. The administrator can confirm that
all guests that are running on the host will not trigger such SErrors. In
this use-case, we should provide some options to administrators to avoid
categorizing SErrors and then reduce the overhead of dsb/isb.
We provided the following 3 options to administrators to determine how
the hypervisors handle SErrors:
* `diverse`:
The hypervisor will distinguish guest SErrors from hypervisor SErrors.
The guest generated SErrors will be forwarded to guests, the hypervisor
generated SErrors will cause the whole system to crash.
It requires:
1. dsb/isb on all EL1 -> EL2 trap entries to categorize SErrors
correctly.
2. dsb/isb on EL2 -> EL1 return paths to prevent slipping hypervisor
SErrors to guests.
3. dsb/isb in context switch to isolate SErrors between 2 vCPUs.
* `forward`:
The hypervisor will not distinguish guest SErrors from hypervisor
SErrors. All SErrors will be forwarded to guests, except the SErrors
generated when the idle vCPU is running. The idle domain doesn't have
the ability to handle SErrors, so we have to crash the whole system when
we get SErros with the idle vCPU. This option will avoid most overhead
of the dsb/isb, except the dsb/isb in context switch which is used to
isolate the SErrors between 2 vCPUs.
* `panic`:
The hypervisor will not distinguish guest SErrors from hypervisor SErrors.
All SErrors will crash the whole system. This option will avoid all
overhead of the dsb/isb pairs.
Signed-off-by: Wei Chen <Wei.Chen@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Having an off by default option allowing guests to join
_any_ shared pool is not very secure.
Lets eliminate tmem_shared_auth bootup option (which
was disabled by default) and have the code force this by default.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Commit 4c8153d9 "add ACPI device for Windows laptop/slate mode switch"
added code to provide an 'laptop/slate mode' ACPI device to guests.
When present this device is used by Microsoft Windows to bind a HID
driver which controls whether the Windows desktop appearance is optimized
for laptop/desktop or slate/tablet PCs. The mechanism for switching
between modes is to open a handle to this driver and write a byte of
arbitrary data.
This patch documents xenstore keys such that a PV agent running in a
Windows guest can advertise the capability to, and receive instruction
from, a toolstack to cause such a mode switch.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Commit 4c8153d9 "add ACPI device for Windows laptop/slate mode switch"
added code that makes use of a new xenstore guest platform key called
'acpi_laptop_slate'. This path needs to be added to the documentation.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Stefano Stabellini