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>
Classic PV shadow paging Dom0 has been broken for years, and can't
possibly be configured after 4045953.
PVH shadow paging Dom0 should still be possible.
Change the code and documentation to clarify that.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper@citrix.com>
Recent discussions on xen-devel have highlighted that to properly
support displacing emulated NVMe disks with PV equivalents will need
updates to PV frontends. Therefore it is important that, if an emulated
NVMe disk is exposed to a guest with an existing PV storage frontend,
that frontend does not inadvertently cause unplug of that emulated
disk when unplugging IDE or SCSI disks.
This patch defines a new bit in the mask used to instruct QEMU to unplug
emulated devices which will instruct QEMU to unplug NVMe disks and limits
the semantics of the existing 'all' disk-unplug bit to only IDE and/or SCSI
disks.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
The current threshold before the guest issues the hypercall is, and always
has been, hard-coded to 2047. It is not clear where this number came
from so, to at least allow for ease of experimentation, this patch makes
the threshold tunable via the Xen command line.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
The Hypervisor Top Level Functional Specification v5.0a states in section
2.5:
"The hypervisor version information is encoded in leaf 0x40000002. Two
version numbers are provided: the main version and the service version.
The main version includes a major and minor version number and a build
number. These correspond to Microsoft Windows release numbers."
It also goes on to advise clients (i.e. guest versions of Windows) to use
the following algorithm to determine compatibility with the hypervisor
enlightenments:
if <your-main-version> greater than <hypervisor-main-version>
{
your version is compatible
}
else if <your-main-version> equal to <hypervisor-main-version> and
<your-service-version> greater than or equal to <hypervisor-service-version>
{
your version is compatible
}
else
{
your version is NOT compatible
}
So, clearly putting Xen hypervisor version information in that leaf is
spurious, but we probably get away with it because Xen's major version
is lower than the major version of Windows in which Hyper-V first
appeared (Server 2008).
This patch changes the leaf to use the kernel major and minor
versions, and build number from Windows Server 2008 (64-bit) by default.
These default values can be overriden from the Xen command line using new
'viridian-version' parameter.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Introduce new Xen command line parameter called "vwfi", which stands for
virtual wfi. The default is "trap": Xen traps guest wfi and wfe
instructions. In the case of wfi, Xen calls vcpu_block on the guest
vcpu; in the case of guest wfe, Xen calls vcpu_yield on the guest vcpu.
The behavior can be changed by setting vwfi to "native", in that case
Xen doesn't trap neither wfi nor wfe, running them in guest context.
The result is strong reduction in irq latency (from 5000ns to 2000ns,
measured using https://github.com/edgarigl/tbm, the physical timer, and
1 pcpu dedicated to 1 vcpu). The downside is that the scheduler thinks
that the guest is busy when actually is sleeping, leading to suboptimal
scheduling decisions.
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
Reviewed-by: Julien Grall <julien.grall@arm.com>
PV Calls is a paravirtualized protocol that allows the implementation of
a set of POSIX functions in a different domain. The PV Calls frontend
sends POSIX function calls to the backend, which implements them and
returns a value to the frontend and acts on the function call.
This version of the document covers networking function calls, such as
connect, accept, bind, release, listen, poll, recvmsg and sendmsg; but
the protocol is meant to be easily extended to cover different sets of
calls. Unimplemented commands return ENOTSUP.
Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
9pfs is a network filesystem protocol developed for Plan 9. 9pfs is very
simple and describes a series of commands and responses. It is
completely independent from the communication channels, in fact many
clients and servers support multiple channels, usually called
"transports". For example the Linux client supports tcp and unix
sockets, fds, virtio and rdma.
This design document outlines the transport protocol for
9pfs payload.
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
As some users have suggested, elaborate the usage of RMRR specification
on the command line, and provide a usage example.
Also, always treat the specified page numbers as hexadecimal values.
Signed-off-by: Venu Busireddy <venu.busireddy@oracle.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
The default dom0_mem is 128M which is not sufficient to boot a Ubuntu
based Dom0. It is not clear what a better default value could be.
Instead, loudly warn the user when dom0_mem is unspecified and wait 3
secs. Then use 512M.
Update the docs to specify that dom0_mem is required on ARM. (The
current xen-command-line document does not actually reflect the current
behavior of dom0_mem on ARM correctly.)
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
PVHv2 guests, unlike HVM guests, won't have the option to route interrupts
from physical or emulated devices over event channels using PIRQs. This
applies to both DomU and Dom0 PVHv2 guests.
Introduce a new XEN_X86_EMU_USE_PIRQ to notify Xen whether a HVM guest can
route physical interrupts (even from emulated devices) over event channels,
and is thus allowed to use some of the PHYSDEV ops.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Split the Dom0 builder into two different functions, one for PV (and classic
PVH), and another one for PVHv2. Introduce a new command line parameter called
'dom0' that can be used to request the creation of a PVHv2 Dom0 by setting the
'hvm' sub-option. A panic has also been added if a user tries to use dom0=hvm
until all the code is in place, then the panic will be removed.
While there mark the dom0_shadow option that was used by PV Dom0 as deprecated,
it was lacking documentation and was not functional. Point users towards
dom0=shadow instead.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
The documentation states that a value of '1' will cause unplug of
emulated IDE disks. This is not quite correct, as QEMU will also unplug
emulated SCSI disks at the same time.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
On some platforms firmware fails to specify RMRR regions in ACPI tables and
thus those regions will not be mapped in dom0 or guests and may cause IO
Page Faults and prevent dom0 from booting if "iommu=dom0-strict" option is
specified on the Xen command line.
New Xen command line option rmrr allows to specify such devices and
memory regions. These regions are added to the list of RMRR defined in ACPI
if the device is present in system. As a result, additional RMRRs will be
mapped 1:1 in dom0 with correct permissions.
The above mentioned problems were discovered during the PVH work with
ThinkCentre M and Dell 5600T. No official documentation was found so far
in regards to what devices and why cause this. Experiments show that
ThinkCentre M USB devices with enabled debug port generate DMA read
transactions to the regions of memory marked reserved in host e820 map.
For Dell 5600T the device and faulting addresses are not found yet.
For detailed history of the discussion please check following threads:
http://lists.Xen.org/archives/html/xen-devel/2015-02/msg01724.htmlhttp://lists.Xen.org/archives/html/xen-devel/2015-01/msg02513.html
Format for rmrr Xen command line option:
rmrr=start<-end>=[s1]bdf1[,[s1]bdf2[,...]];start<-end>=[s2]bdf1[,[s2]bdf2[,...]]
For example, for Lenovo ThinkCentre M, use:
rmrr=0xd5d45=0:0:1d.0;0xd5d46=0:0:1a.0
If grub2 used and multiple ranges are specified, ';' should be
quoted/escaped, refer to grub2 manual for more information.
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: Venu Busireddy <venu.busireddy@oracle.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Wei Liu
George Dunlap
Roger Pau Monne
Dario Faggioli
Joao Martins
Juergen Gross
Bhupinder Thakur
Vivek Kumar Chaubey
Jan Beulich
Yi Sun
Andrii Anisov
Konrad Rzeszutek Wilk
Praveen Kumar
Andrew Cooper
Stefano Stabellini
Simon Crowe
Swapnil Paratey
Andre Przywara
Wei Chen
Konrad Rzeszutek Wilk
Paul Durrant
Stefano Stabellini
Venu Busireddy
Olaf Hering
Elena Ufimtseva