MISRA C:2012 Rule 16.4 states that "Every switch statement shall have a
default label".
Update ECLAIR configuration to take into account the deviations
agreed during MISRA meetings.
Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Add a section for terms and definitions used by MISRA but expressed
in terms of the C specification.
Add a definition of "switch clause" to the newly-introduced section.
Link the first use of the term "switch clause" in the document to its
definition.
Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
In order to make implementation and testing tractable, we will require
specific host functionality. Add a nested_virt bit to hvm_funcs.caps,
and return an error if a domain is created with nested virt and this
bit isn't set. Create VMX and SVM callbacks to be executed from
nestedhvm_setup(), which is guaranteed to execute after all
command-line options have been procesed.
For VMX, start with always enabling it if HAP is present; this
shouldn't change current behvior.
For SVM, require some basic functionality, adding a document
explaining the rationale.
NB that only SVM CPUID bits 0-7 have been considered. Bits 10-16 may
be considered in a follow-up patch.
Signed-off-by: George Dunlap <george.dunlap@cloud.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
MISRA C Rule 16.2 states:
"A switch label shall only be used when the most closely-enclosing
compound statement is the body of a switch statement".
The PROGRESS_VCPU local helper specifies a case that is directly
inside the compound statement of a for loop, hence violating the rule.
To avoid this, the construct is deviated with a text-based deviation.
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
MISRA C Rule 16.2 states:
"A switch label shall only be used when the most closely-enclosing
compound statement is the body of a switch statement".
Since complying with this rule of the x86 emulator would lead to
a lot of code duplication, it is deemed better to exempt those
files for this guideline.
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Since commit 6cd046c501 ("xen/arm: Enlarge identity map space to 10TB")
Xen can be loaded below 10 TiB. Update docs accordingly.
Take the opportunity to update stale links to Linux docs.
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Xen doesn't care (and indeed, cannot feasibly tell) whether a hypercall was
initiated using the hypercall page or not.
For SEV-SNP/TDX encrypted VMs, use of a hypercall page would violate the
integrity properties wanted.
Explicitly state that the hypercall page is optional.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
xl/libxl only applies vkb=[] to PV & PVH guests. HVM gets only a single
vkb by default, but that can be disabled by the vkb_device boolean.
Notably the HVM vkb cannot be configured, so feature-abs-pointer or the
backend-type cannot be specified.
Re-arrange the logic so that vkb=[] is handled regardless of domain
type. If vkb is empty or unspecified, follow the vkb_device boolean for
HVMs. Nothing changes for PVH & PV. HVMs can now get a configured vkb
instead of just the default one.
The chance for regression is an HVM config with
vkb=["$something"]
vkb_device=false
Which would now get a vkb.
This is useful for vGlass which provides a VKB to HVMs. vGlass wants to
specify feature-abs-pointer, but that is racily written by vGlass
instead of coming through the xl.cfg. Unhelpfully, Linux xen-kbdfront
reads the backend nodes without checking that the backend is in
InitWait.
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Signed-off-by: Jason Andryuk <jason.andryuk@amd.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Xen makes assumptions about the size of integer types on the various
architectures. Document these assumptions.
Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Acked-by: Bertrand Marquis <bertrand.marquis@arm.com>
Out of an abudnance of caution, implement the long loop too, and allowing for
it to be opted in to.
This is part of XSA-456 / CVE-2024-2201.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
In the absence of BHI_DIS_S, mitigating Native-BHI requires the use of a
software sequence.
Introduce a new bhb-seq= option to select between avaialble sequences and
bhb-entry= to control the per-PV/HVM actions like we have for other blocks.
Activate the short sequence by default for PV and HVM guests on affected
hardware if BHI_DIS_S isn't present.
This is part of XSA-456 / CVE-2024-2201.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Introduce a "bhi-dis-s" boolean to match the other options we have for
MSR_SPEC_CTRL values. Also introduce bhi_calculations().
Use BHI_DIS_S whenever possible.
Guests which are levelled to be migration compatible with older CPUs can't see
BHI_DIS_S, and Xen must fill in the difference to make the guest safe. Use
the virt MSR_SPEC_CTRL infrastructure to force BHI_DIS_S behind the guest's
back.
This is part of XSA-456 / CVE-2024-2201.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
The Xen community wants to avoid using variadic functions except for
specific circumstances where it feels appropriate by strict code review.
Functions hypercall_create_continuation and hypercall_xlat_continuation
are internal helper functions made to break long running hypercalls into
multiple calls. They take a variable number of arguments depending on the
original hypercall they are trying to continue.
Add SAF deviations for the aforementioned functions.
Signed-off-by: Simone Ballarin <simone.ballarin@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
The Xen community wants to avoid using variadic functions except for
specific circumstances where it feels appropriate by strict code review.
Add deviation for printf()-like functions.
Signed-off-by: Simone Ballarin <simone.ballarin@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
These deviations deal with the following cases:
- macro arguments used directly as initializer list arguments;
- uses of the __config_enabled macro, that can't be brought
into compliance without breaking its functionality;
- exclude files that are out of scope (efi headers and cpu_idle);
- uses of alternative_{call,vcall}[0-9] macros.
The existing configuration for R20.7 is reordered so that it matches the
cases listed in its documentation comment.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Currently, RISC-V requires two extensions: _zbb and _zihintpause.
This patch introduces a compiler check to check if these extensions
are supported.
Additionally, it introduces the riscv/booting.txt file, which contains
information about the extensions that should be supported by the platform.
In the future, a feature will be introduced to check whether an extension
is supported at runtime.
However, this feature requires functionality for parsing device tree
source (DTS), which is not yet available.
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
As agreed during MISRA C meetings, add Rule 13.6 to rules.rst, with a
note about extending the rule to alignof and typeof. Also take the
opportunity to remove an older and out of order entry for the same rule.
Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Commit d638e304f1 introduced a bullet list, but parse-support-md
choke on it as it doesn't know what to do about it.
Introduce ri_BulletList() so that r_content() will find this new
function and call it instead of calling process_unknown().
Reported-by: Julien Grall <julien@xen.org>
Fixes: d638e304f1 ("SUPPORT.MD: Fix matrix generation after 43c416d0d8 and 77c39a53cf5b")
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Tested-by: Julien Grall <jgrall@amazon.com>
Acked-by: Julien Grall <jgrall@amazon.com>
Update ECLAIR configuration of MISRA C:2012 Rule 8.3 to deviate
violations involving parameter name "unused" (with an optional
numeric suffix): it makes explicit the intention of not using such
parameter within the function.
Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
There can be situations when the registers cannot be emulated to their full
functionality. This can be due to the complexity involved. In such cases, one
can emulate those registers as RAZ/WI for example. We call them as partial
emulation.
Some registers are non-optional and as such there is nothing preventing an OS
from accessing them.
Instead of injecting undefined exception (which might result in crashing a
guest), one may want to prefer a partial emulation to let the guest running
(in some cases accepting the fact that it might result in unwanted behavior).
A suitable example of this (as seen in subsequent patches) is emulation of
DBGDTRTX_EL0 (on Arm64) and DBGDTRTXINT(on Arm32). These non-optional
registers can be emulated as RAZ/WI and they can be enclosed within
CONFIG_PARTIAL_EMULATION.
Further, "partial-emulation" command line option allows us to
enable/disable partial emulation at run time. While CONFIG_PARTIAL_EMULATION
enables support for partial emulation at compile time (i.e. adds code for
partial emulation), this option may be enabled or disabled by Yocto or other
build systems. However if the build system turns this option on, users
can use scripts like Imagebuilder to generate uboot-script which will append
"partial-emulation=true" to xen command line to turn on the partial emulation.
Thus, it helps to avoid rebuilding xen.
By default, "CONFIG_PARTIAL_EMULATION=y" and "partial-emulation=false".
This is done so that Xen supports partial emulation. However, customers are
fully aware when they enable partial emulation. It's important to note that
enabling such support might result in unwanted/non-spec compliant behavior.
Added a note in SUPPORT.md to clarify the security support for partial
emulation.
Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Acked-by: Julien Grall <jgrall@amazon.com>
Rule 20.4 states: "A macro shall not be defined with the same name
as a keyword".
Defining this macro with the same name as the inline keyword
allows for additionally checking that out-of-lined static inline
functions end up in the correct section while minimizing churn and
has a positive impact on the overall safety. See [1] for additional
context on the motivation of this deviation.
No functional change.
[1] https://lore.kernel.org/xen-devel/adaa6d55-266d-4df8-8967-9340080d17e4@citrix.com/
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
... by way of a new arch-selectable Kconfig control.
Note that some smaller pieces of code are left without #ifdef, to keep
things better readable. Hence items like ECS_PIRQ, nr_static_irqs, or
domain_pirq_to_irq() remain uniformly.
As to XEN_DOMCTL_irq_permission - this, despite having a uniformly
available wrapper in libxc, is unused on Arm: libxl bypasses those
calls, and the Python and OCamL bindings have no users at all.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <jgrall@amazon.com>
Certain macros are allowed to violate the Rule, since their meaning and
intended use is well-known to all Xen developers.
Variadic macros that rely on the GCC extension for removing a trailing
comma when token pasting the variable argument are similarly
well-understood and therefore allowed.
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Introduce a new Kconfig option to block speculation into lock protected
critical regions. The Kconfig option is enabled by default, but the mitigation
won't be engaged unless it's explicitly enabled in the command line using
`spec-ctrl=lock-harden`.
Convert the spinlock acquire macros into always-inline functions, and introduce
a speculation barrier after the lock has been taken. Note the speculation
barrier is not placed inside the implementation of the spin lock functions, as
to prevent speculation from falling through the call to the lock functions
resulting in the barrier also being skipped.
trylock variants are protected using a construct akin to the existing
evaluate_nospec().
This patch only implements the speculation barrier for x86.
Note spin locks are the only locking primitive taken care in this change,
further locking primitives will be adjusted by separate changes.
This is part of XSA-453 / CVE-2024-2193
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
VERW is going to be used for a 3rd purpose, and the existing nomenclature
didn't survive the Stale MMIO issues terribly well.
Rename the command line option from `md-clear=` to `verw=`. This is more
consistent with other options which tend to be named based on what they're
doing, not which feature enumeration they use behind the scenes. Retain
`md-clear=` as a deprecated alias.
Rename opt_md_clear_{pv,hvm} and opt_fb_clear_mmio to opt_verw_{pv,hvm,mmio},
which has a side effect of making spec_ctrl_init_domain() rather clearer to
follow.
No functional change.
This is part of XSA-452 / CVE-2023-28746.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Update ECLAIR configuration to take into account the deviations
agreed during MISRA meetings.
Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Commit 4cac80e226 broke the CI cppcheck jobs by adding an entry for
a rule 20.12 with "Severity" and "Summary" fields placed in reverse order.
This leads to an error as reported by convert_misra_doc.py:
No summary for rule 20.12
Fixes: 4cac80e226 ("docs/misra/rules.rst: add rule 16.6 and 20.12")
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
The list of function/macro properties is not MISRA-specific documentation.
Their addition was directly motivated to address MISRA findings and they
are not used elsewhere. For this reason, this patch moves these properties
in docs/misra.
This patch also fixes a Sphinx warning caused by the missing inclusion
of the rst file in the toctree.
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Fixes: f4519ee8 ("eclair: move function and macro properties outside ECLAIR")
Signed-off-by: Simone Ballarin <simone.ballarin@bugseng.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
find-next-bit.c is common for Arm64, PPC and RISCV64,
so it is moved to xen/lib.
PPC has been transitioned to generic functions from find-next-bit.c
since it now shares the same implementation as the PPC-specific code.
The MISRA exclude list has been updated to verify
lib/find-next-bit.c instead of Arm's find_next_bit.c,
as Arm's find_next_bit.c has been relocated to xen/lib/.
Despite CONFIG_GENERIC_FIND_FIRST_BIT not currently being used in
Xen and being removed from the Linux kernel [1], it could theoretically
prove useful for Xen. This is because the Linux kernel transitioned
Arm to the generic version of find_first_bit() and
find_first_zero_bit() due to improvements [1] in both performance
and .text size.
It would be prudent to investigate whether [1] is applicable to Xen
as well and, if so, implement the necessary changes in a separate patch.
[1] https://lore.kernel.org/linux-arch/20211005054059.475634-5-yury.norov@gmail.com/
Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Shawn Anastasio <sanastasio@raptorengineering.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Attempt to provide a more helpful error message when the user attempts to set
spec-ctrl=bti-thunk option but the support is build-time disabled.
While there also adjust the command line documentation to mention
CONFIG_INDIRECT_THUNK instead of INDIRECT_THUNK.
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Add support for the new 9pfs backend "xen_9pfsd". For this backend type
the tag defaults to "Xen" and the host side path to
"/var/log/xen/guests/<dom-name>".
Do most of the default settings in libxl. Unfortunately the default
path can't easily be set in libxl, as the domain name isn't available
in the related 9pfs specific function.
Settings the defaults in libxl requires to move the sanity checking
of 9pfs parameters from xl to libxl, too.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Implement the in-code suppression comment at the end of the line.
Now it is possible to add a Xen deviaiton comment with the syntax
described in the docs at the end of the line affected by the
violation, to deviate it.
Eclair natively supports it, so the translation for the tool will
be straighforward, but the other tool needs to translate an
occurrence of the tag into a suppressino comment at the end of the
previous line, this will have a corner case where the line number
1 of the file can't be deviated in this way for such tools.
Updated documentation.
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Allow administrators to control whether Xen grant mappings for
the virtio disk devices should be used. By default (when new
parameter is not specified), the existing behavior is retained
(we enable grants if backend-domid != 0).
Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Today the CODING_STYLE contains a section "Handling unexpected
conditions" specific to the hypervisor. This section is kind of
misplaced for a coding style. It should rather be part of a "Coding
best practices" guide.
Add such a guide as docs/process/coding-best-practices.pandoc and
move the mentioned section from CODING_STYLE to the new file, while
converting the format to pandoc.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Julien Grall <jgrall@amazon.com>
Add a command line option to xentop to be able to display dom0 first, on top of the list.
This is unconditional, so sorting domains with the S option will also ignore dom0.
Signed-off-by: Cyril Rébert (zithro) <slack@rabbit.lu>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
These files contain several deliberate violations of MISRA C rules such
as:
* R20.12 for macros DEFINE and OFFSET, where the second argument
of OFFSET is a macro and is used as a normal parameter and a
stringification operand.
* R2.1 because the file is not linked. That said it was decided to
deviate the rule itself to address that aspect).
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <jgrall@amazon.com>
This patch re-introduces blktap support to libxl. Unlike earlier
versions, it does not link against any blktap library. libxl changes
are needed to write to the vbd3 backend XenStore nodes.
blktap has three components. tapdisk is a daemon implementing the disk
IO, NBD (Network Block Device), and Xen PV interfaces. tap-ctl is a
tool to control tapdisks - creating, starting, stopping and freeing.
tapback manages the XenStore operations and instructs tapdisk to
connect.
It is notable that tapdisk performs the grant and event channel ops, but
doesn't interact with XenStore. tapback performs XenStore operations
and notifies tapdisks of values and changes.
The flow is: libxl writes to the "vbd3" XenStore nodes and runs the
block-tap script. The block-tap script runs tap-ctl to create a tapdisk
instance as the physical device. tapback then sees the tapdisk and
instructs the tapdisk to connect up the PV blkif interface.
This is expected to work without the kernel blktap driver, so the
block-tap script is modified accordingly to write the UNIX NBD path.
backendtype=tap was not fully removed previously, but it would never
succeed since it would hit the hardcoded error in disk_try_backend().
It is reused now.
An example command to attach a vhd:
xl block-attach vm 'vdev=xvdf,backendtype=tap,format=vhd,target=/srv/target.vhd'
Format raw also works to run an "aio:" tapdisk.
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Function and macro properties contained in ECLAIR/call_properties.ecl are of
general interest: this patch moves these annotations in a generaric JSON file
in docs. In this way, they can be exploited for other purposes (i.e. documentation,
other tools).
Add rst file containing explanation on how to update function_macro_properties.json.
Add script to convert the JSON file in ECL configurations.
Remove ECLAIR/call_properties.ecl: the file is now automatically generated from
the JSON file.
Signed-off-by: Maria Celeste Cesario <maria.celeste.cesario@bugseng.com>
Signed-off-by: Simone Ballarin <simone.ballarin@bugseng.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
In 13y of working on Xen, I've never seen seen it used. The implementation
was introduced (commit b69f92f301, Jul 28 2004) with known issues such as:
/* Resuming after we've stopped used to work, but more through luck
than any actual intention. It doesn't at the moment. */
which appear to have gone unfixed for the 20 years since.
Nowadays there are more robust ways of inspecting crashed state, such as a
kexec crash kernel, or running Xen in a VM.
This will allow us to clean up some hooks around the codebase which are
proving awkward for other tasks.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
The HVM pirq feature allows routing interrupts from both physical and emulated
devices over event channels, this was done a performance improvement. However
its usage is fully undocumented, and the only reference implementation is in
Linux. It defeats the purpose of local APIC hardware virtualization, because
when using it interrupts avoid the usage of the local APIC altogether.
It has also been reported to not work properly with certain devices, at least
when using some AMD GPUs Linux attempts to route interrupts over event
channels, but Xen doesn't correctly detect such routing, which leads to the
hypervisor complaining with:
(XEN) d15v0: Unsupported MSI delivery mode 7 for Dom15
When MSIs are attempted to be routed over event channels the entry delivery
mode is set to ExtINT, but Xen doesn't detect such routing and attempts to
inject the interrupt following the native MSI path, and the ExtINT delivery
mode is not supported.
Disable HVM PIRQs by default and provide a per-domain option in xl.cfg to
enable such feature. Also for backwards compatibility keep the feature enabled
for any resumed domains that don't have an explicit selection.
Note that the only user of the feature (Linux) is also able to handle native
interrupts fine, as the feature was already not used if Xen reported local APIC
hardware virtualization active.
Link: https://github.com/QubesOS/qubes-issues/issues/7971
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
The files under 'include/acpi/ac*.h' and 'include/acpi/plaform/ac*.h'
are inherited from Linux and ACPI CA, therefore they are not subject to
MISRA compliance at the moment.
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Federico Serafini