When building a PVH dom0 Xen attempts to map all (relevant) MMIO regions
into the p2m for dom0 access. However the information Xen has about the
host memory map is limited. Xen doesn't have access to any resources
described in ACPI dynamic tables, and hence the p2m mappings provided might
not be complete.
PV doesn't suffer from this issue because a PV dom0 is capable of mapping
into it's page-tables any address not explicitly banned in d->iomem_caps.
Introduce a new command line options that allows Xen to attempt to fixup
the p2m page-faults, by creating p2m identity maps in response to p2m
page-faults.
This is aimed as a workaround to small ACPI regions Xen doesn't know about.
Note that missing large MMIO regions mapped in this way will lead to
slowness due to the VM exit processing, plus the mappings will always use
small pages.
The ultimate aim is to attempt to bring better parity with a classic PV
dom0.
Note such fixup rely on the CPU doing the access to the unpopulated
address. If the access is attempted from a device instead there's no
possible way to fixup, as IOMMU page-fault are asynchronous.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
master commit: 104591f5dd
master date: 2025-03-05 10:26:46 +0100
AMD have updated the SRSO whitepaper[1] with further information. These
features exist on AMD Zen5 CPUs and are necessary for Xen to use.
The two features are in principle unrelated:
* SRSO_U/S_NO is an enumeration saying that SRSO attacks can't cross the
User(CPL3) / Supervisor(CPL<3) boundary. i.e. Xen don't need to use
IBPB-on-entry for PV64. PV32 guests are explicitly unsupported for
speculative issues, and excluded from consideration for simplicity.
* SRSO_MSR_FIX is an enumeration identifying that the BP_SPEC_REDUCE bit is
available in MSR_BP_CFG. When set, SRSO attacks can't cross the host/guest
boundary. i.e. Xen don't need to use IBPB-on-entry for HVM.
Extend ibpb_calculations() to account for these when calculating
opt_ibpb_entry_{pv,hvm} defaults. Add a `bp-spec-reduce=<bool>` option to
control the use of BP_SPEC_REDUCE, with it active by default.
Because MSR_BP_CFG is core-scoped with a race condition updating it, repurpose
amd_check_erratum_1485() into amd_check_bp_cfg() and calculate all updates at
once.
Xen also needs to to advertise SRSO_U/S_NO to guests to allow the guest kernel
to skip SRSO mitigations too:
* This is trivial for HVM guests. It is also is accurate for PV32 guests
too, but we have already excluded them from consideration, and do so again
here to simplify the policy logic.
* As written, SRSO_U/S_NO does not help for the PV64 user->kernel boundary.
However, after discussing with AMD, an implementation detail of having
BP_SPEC_REDUCE active causes the PV64 user->kernel boundary to have the
property described by SRSO_U/S_NO, so we can advertise SRSO_U/S_NO to
guests when the BP_SPEC_REDUCE precondition is met.
Finally, fix a typo in the SRSO_NO's comment.
[1] https://www.amd.com/content/dam/amd/en/documents/corporate/cr/speculative-return-stack-overflow-whitepaper.pdf
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: a1746cd443
master date: 2025-01-02 18:44:49 +0000
Rename all instances of ECLAIR MISRA C:2012 service identifiers,
identified by the prefix MC3R1, to use the prefix MC3A2, which
refers to MISRA C:2012 Amendment 2 guidelines.
This update is motivated by the need to upgrade ECLAIR GitLab runners
that use the new naming scheme for MISRA C:2012 Amendment 2 guidelines.
Changes to the docs/misra directory are needed in order to keep
comment-based deviation up to date.
Signed-off-by: Alessandro Zucchelli <alessandro.zucchelli@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
(cherry picked from commit 631f535a3d)
Right now, Xen clobbers the value at 0xffc when performing it's load-base
calculation. We've got plenty of free registers at this point, so the value
can be preserved easily.
This fixes a real bug booting under Coreboot+SeaBIOS, where 0xffc happens to
be the cbmem pointer (e.g. Coreboot's dmesg ring, among other things).
However, there's also a better choice of memory location to use than 0xffc, as
all our supported boot protocols have a pointer to an info structure in %ebx.
Update the documentation to match.
Fixes: 1695e53851 ("x86/boot: Fix the boot time relocation calculations")
Fixes: d96bb172e8 ("x86/entry: Early PVH boot code")
Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: e58a2858d5
master date: 2024-08-27 18:08:19 +0100
PVH in particular has no (externally visible) notion of pIRQ-s. Mention
that in the description of the respective command line option and have
arch_hwdom_irqs() also reflect this (thus suppressing the log message
there as well, as being pretty meaningless in this case anyway).
Suggested-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
PHYSDEVOP_pirq_eoi_gmfn_v<N> accepting just a single GFN implies that no
more than 32k pIRQ-s can be used by a domain on x86. Document this upper
bound.
To also enforce the limit, (ab)use both arch_hwdom_irqs() (changing its
parameter type) and setup_system_domains(). This is primarily to avoid
exposing the two static variables or introducing yet further arch hooks.
While touching arch_hwdom_irqs() also mark it hwdom-init.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Update ECLAIR configuration to take into account the deviations
agreed during the MISRA meetings.
While doing this, remove the obsolete "Set [123]" comments.
Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@gmail.com>
MISRA C Rule 20.7 states: "Expressions resulting from the expansion
of macro parameters shall be enclosed in parentheses".
The local helpers GRP2 and XADD in the x86 emulator use their first
argument as the constant expression for a case label. This pattern
is deviated project-wide, because it is very unlikely to induce
developer confusion and result in the wrong control flow being
carried out.
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
MISRA C Rule 20.7 states: "Expressions resulting from the expansion
of macro parameters shall be enclosed in parentheses".
The helper macro bitmap_switch has parameters that cannot be parenthesized
in order to comply with the rule, as that would break its functionality.
Moreover, the risk of misuse due developer confusion is deemed not
substantial enough to warrant a more involved refactor, thus the macro
is deviated for this rule.
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Rule 13.6 states that "The operand of the `sizeof' operator shall not
contain any expression which has potential side effects".
Define service B.UNEVALEFF as an extension of Rule 13.6 to
check for unevalued side effects also for typeof and alignof operators.
Update ECLAIR configuration to deviate uses of BUILD_BUG_ON and
alternative_v?call[0-9] for both Rule 13.6 and B.UNEVALEFF.
Add service B.UNEVALEFF to the accepted.ecl guidelines to check
"violations" in the weekly analysis.
Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@gmail.com>
MISRA C Rule 5.5 states that "Identifiers shall be distinct from macro
names".
Update ECLAIR configuration to deviate:
- macros expanding to their own name;
- clashes between macros and non-callable entities;
- clashes related to the selection of specific implementations of string
handling functions.
Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
With the new allocation strategy of Dom0less DomUs XenStore page,
update the doc of the late XenStore init protocol accordingly.
Signed-off-by: Henry Wang <xin.wang2@amd.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Currently, users are allowed to map static shared memory in a
non-direct-mapped way for direct-mapped domains. This can lead to
clashing of guest memory spaces. Also, the current extended region
finding logic only removes the host physical addresses of the
static shared memory areas for direct-mapped domains, which may be
inconsistent with the guest memory map if users map the static
shared memory in a non-direct-mapped way. This will lead to incorrect
extended region calculation results.
To make things easier, add restriction that static shared memory
should also be direct-mapped for direct-mapped domains. Check the
host physical address to be matched with guest physical address when
parsing the device tree. Document this restriction in the doc.
Signed-off-by: Henry Wang <xin.wang2@amd.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Acked-by: Michal Orzel <michal.orzel@amd.com>
This commit describe the new scenario where host address is not provided
in "xen,shared-mem" property and a new example is added to the page to
explain in details.
Take the occasion to fix some typos in the page.
Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
MISRA C Rule 20.12 states: "A macro parameter used as an operand to
the # or ## operators, which is itself subject to further macro replacement,
shall only be used as an operand to these operators".
In this case, builds where CONFIG_COMPAT=y the fpu_ctxt
macro is used both as a regular macro argument and as an operand for
stringification in the expansion of CHECK_FIELD_.
This is deviated using a SAF-x-safe comment.
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
These files are used when debugging Xen, and are not meant to comply
with MISRA rules at the moment.
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Currently, the number of SPIs allocated to the domain is only
configurable for Dom0less DomUs. Xen domains are supposed to be
platform agnostics and therefore the numbers of SPIs for libxl
guests should not be based on the hardware.
Introduce a new xl config entry for Arm to provide a method for
user to decide the number of SPIs. This would help to avoid
bumping the `config->arch.nr_spis` in libxl everytime there is a
new platform with increased SPI numbers.
Update the doc and the golang bindings accordingly.
Signed-off-by: Henry Wang <xin.wang2@amd.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
There are some use cases in which the dom0less domUs need to have
the XEN_DOMCTL_CDF_iommu set at the domain construction time. For
example, the dynamic dtbo feature allows the domain to be assigned
a device that is behind the IOMMU at runtime. For these use cases,
we need to have a way to specify the domain will need the IOMMU
mapping at domain construction time.
Introduce a "passthrough" DT property for Dom0less DomUs following
the same entry as the xl.cfg. Currently only provide two options,
i.e. "enable" and "disable". Set the XEN_DOMCTL_CDF_iommu at domain
construction time based on the property.
Signed-off-by: Henry Wang <xin.wang2@amd.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
xentrace_format was always of limited utility, since trace records
across pcpus were processed out of order; it was superseded by xenalyze
over a decade ago.
But for several releases, the `formats` file it has depended on for
proper operation has not even been included in `make install` (which
generally means it doesn't get picked up by distros either); yet
nobody has seemed to complain.
Simple remove xentrace_format, and point people to xenalyze instead.
NB that there is no man page for xenalyze, so the "see also" on the
xentrace man page is simply removed for now.
Signed-off-by: George Dunlap <george.dunlap@cloud.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Olaf Hering <olaf@aepfle.de>
By default there's already no use for this when we run in shim mode.
Plus there may also be a need to suppress the probing in case of issues
with it. Before introducing further port alias probing, introduce a
command line option allowing to bypass it, default it to on when in shim
mode, and gate RTC/CMOS port alias probing on it.
Requested-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
The count_args_ macro violates Rule 20.7, but it can't be made
compliant with Rule 20.7 without breaking its functionality. Since
it's very unlikely for this macro to be misused, it is deviated.
No functional change.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
These rules are concerned with the use of facilities provided by the
C Standard Library (qsort, bsearch for rule 21.9, and those provided
by <time.h> for rule 21.10).
Xen provides in its source code its own implementation of some of these
functions and macros, therefore a justification is provided for allowing
uses of these functions in the project.
The rules are also marked as clean as a consequence.
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Update parse_nic_config() to support a new `vlan' keyword. This
keyword specifies the VLAN configuration to assign to the VIF when
attaching it to the bridge port, on operating systems that support
the capability (e.g. Linux). The vlan keyword will allow one or
more VLANs to be configured on the VIF when adding it to the bridge
port. This will be done by the vif-bridge script and functions.
Signed-off-by: Leigh Brown <leigh@solinno.co.uk>
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>
Update ECLAIR configuration to take into account the deviations
agreed during MISRA meetings.
Amend an existing entry of Rule 14.4 in deviations-rst:
it is not a project-wide deviation.
Tag Rule 14.4 as clean for arm.
Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
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>
Andrew Cooper