Commit Graph
20 Commits
Author SHA1 Message Date
Stefano Stabellini 52196c8cd9 docs: document dom0less + PV drivers
Document how to use the feature and how the implementation works.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>
2022-07-20 19:06:33 +01:00
Stefano Stabellini 8c1cc69748 docs/misra: add Rule 5.1
Add Rule 5.1, with the additional note that the character limit for Xen
is 40 characters.

The max length identifiers found by ECLAIR are:

__mitigate_spectre_bhb_clear_insn_start
domain_pause_by_systemcontroller_nosync

Both of them are 40 characters long.

Explicitly mention that public headers might have longer identifiers.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Acked-by: Julien Grall <jgrall@amazon.com>
2022-06-07 17:44:03 -07:00
Stefano Stabellini 4b08435f58 docs/misra: introduce rules.rst
Introduce a list of MISRA C rules that apply to the Xen hypervisor. The
list is in RST format.

Specify that rules deviations need to be documented. Introduce a
documentation tag for in-code comments to mark them as deviations. Also
mention that other documentation mechanisms are work-in-progress.

Add a mention of the new list to CODING_STYLE.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>
2022-06-07 17:43:47 -07:00
Stefano Stabellini 09a6a71097 init-dom0less: better snprintf checks
snprintf returns the number of characters that would have been written
to the final string if enough space had been available. A return value
of size or more means that the output was truncated.

Add a check for that in init-dom0less.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Michal Orzel <michal.orzel@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>
2022-05-31 13:01:24 -07:00
Stefano Stabellini 5eedfe7728 xen: introduce xen,enhanced dom0less property
Introduce a new "xen,enhanced" dom0less property to enable/disable PV
driver interfaces for dom0less guests. Currently only "enabled" and
"disabled" are supported property values (and empty). Leave the option
open to implement further possible values in the future (e.g.
"xenstore" to enable only xenstore.) Dom0 presence is required for now
to use "xen,enhanced" on a domU.

The configurable option is for domUs only. For dom0 we always set the
corresponding property in the Xen code to true (PV interfaces enabled.)

This patch only parses the property. Next patches will make use of it.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Acked-by: Julien Grall <jgrall@amazon.com>
CC: Julien Grall <julien@xen.org>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
CC: Bertrand Marquis <bertrand.marquis@arm.com>
2022-05-24 16:16:42 -07:00
Stefano Stabellini 2a2447757b xen/arm: implement domU extended regions
Implement extended regions for dom0less domUs. The implementation is
based on the libxl implementation.

Also update docs for the ext_regions command line option.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Acked-by: Julien Grall <jgrall@amazon.com>
2022-05-24 16:12:09 -07:00
Stefano Stabellini d43d2b6056 xen/dt: of_property_read_string return -ENODATA when !length
When the length of the string is zero of_property_read_string should
return -ENODATA according to the description of the function.

However, of_property_read_string doesn't check prop->length. If
prop->length is zero, return -ENODATA.

Without this patch the following command in u-boot:

fdt set /chosen/node property-name

results in of_property_read_string returning -EILSEQ when attempting to
read property-name. With this patch, it returns -ENODATA as expected.

This commit is a backport of:
https://lore.kernel.org/xen-devel/20220416003028.1315268-1-sstabellini@kernel.org/

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
2022-05-24 16:11:06 -07:00
Stefano Stabellini 43f3d51139 gitlab-ci: add an ARM32 qemu-based smoke test
Add a minimal ARM32 smoke test based on qemu-system-arm, as provided by
the test-artifacts qemu container. The minimal test simply boots Xen
(built from previous build stages) and Dom0.

The test needs a working kernel and minimal initrd for dom0. Instead of
building our own kernel and initrd, which would mean maintaining one or
two more builting scripts under automation/, we borrow a kernel and
initrd from distros.

For the kernel we pick the Debian Bullseye kernel, which has everything
we need already built-in. However, we cannot use the Debian Bullseye
initrd because it is 22MB and the large size causes QEMU to core dump.

Instead, use the tiny busybox-based rootfs provided by Alpine Linux,
which is really minimal: just 2.5MB. Note that we cannot use the Alpine
Linux kernel because that doesn't boot on Xen.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Michal Orzel <michal.orzel@arm.com>
2022-04-21 16:17:40 -07:00
Stefano Stabellini f1e4efafd6 gitlab-ci: add qemu-system-arm to the existing tests-artifacts container
Add qemu-system-arm to the existing test-artifacts qemu container (which
doesn't get build for every iteration but only updated once in a while.)

With qemu-system-arm available, we'll be able to run ARM32 tests.

This patch also bumps the QEMU version to v6.0.0 for both arm32 and
arm64 (the test-artifacts container is one, shared for both).

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
2022-04-21 16:17:20 -07:00
Stefano Stabellini 0e03ff97de xen/arm: set CPSR Z bit when creating aarch32 guests
The first 32 bytes of zImage are NOPs. When CONFIG_EFI is enabled in the
kernel, certain versions of Linux will use an UNPREDICTABLE NOP
encoding, sometimes resulting in an unbootable kernel. Whether the
resulting kernel is bootable or not depends on the processor. See commit
a92882a4d270 in the Linux kernel for all the details.

All kernel releases starting from Linux 4.9 without commit a92882a4d270
are affected.

Fortunately there is a simple workaround: setting the "Z" bit in CPSR
make it so those invalid NOP instructions are never executed. That is
because the instruction is conditional (not equal). So, on QEMU at
least, the instruction will end up to be ignored and not generate an
exception. Setting the "Z" bit makes those kernel versions bootable
again and it is harmless in the other cases.

Note that both U-Boot and QEMU -kernel set the "Z" bit in CPSR when
booting a zImage kernel on aarch32.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Wei Chen <Wei.Chen@arm.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>
2022-03-25 09:50:02 +00:00
Stefano Stabellini 2a565f9b40 automation: remove python-dev from debian unstable build containers
Debian unstable doesn't have the legacy python-dev package anymore.
Note: only the arm64v8 container has been rebuilt.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
2022-01-27 17:20:50 -08:00
Stefano Stabellini d8e1ed865a xen/arm: allocate_bank_memory: don't create memory banks of size zero
allocate_bank_memory can be called with a tot_size of zero, as an
example see the implementation of allocate_memory which can call
allocate_bank_memory with a tot_size of zero for the second memory bank.

If tot_size == 0, don't create an empty memory bank, just return
immediately without error. Otherwise a zero-size memory bank will be
added to the domain device tree.

Note that Linux is known to be able to cope with zero-size memory banks,
and Xen more recently gained the ability to do so as well (5a37207df5
"xen/arm: bootfdt: Ignore empty memory bank"). However, there might be
other non-Linux OSes that are not able to cope with empty memory banks
as well as Linux (and now Xen). It would be more robust to avoid
zero-size memory banks unless required.

Moreover, the code to find empty address regions in make_hypervisor_node
in Xen is not able to cope with empty memory banks today and would
result in a Xen crash. This is only a latent bug because
make_hypervisor_node is only called for Dom0 at present and
allocate_memory is only called for DomU at the moment. (But if
make_hypervisor_node was to be called for a DomU, then the Xen crash
would become manifest.)

Fixes: f2931b4233 ("xen/arm: introduce allocate_memory")
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Release-Acked-by: Ian Jackson <iwj@xenproject.org>
2021-11-11 10:35:13 -08:00
Stefano Stabellini 9aaf437cd3 xen/arm: don't assign domU static-mem to dom0 as reserved-memory
DomUs static-mem ranges are added to the reserved_mem array for
accounting, but they shouldn't be assigned to dom0 as the other regular
reserved-memory ranges in device tree.

In make_memory_nodes, fix the error by skipping banks with xen_domain
set to true in the reserved-memory array. Also make sure to use the
first valid (!xen_domain) start address for the memory node name.

Fixes: 41c031ff43 ("xen/arm: introduce domain on Static Allocation")
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Penny Zheng <penny.zheng@arm.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Release-Acked-by: Ian Jackson <iwj@xenproject.org>
2021-11-11 10:34:18 -08:00
Stefano Stabellini 3030a73bf8 automation: add a QEMU based x86_64 Dom0/DomU test
Introduce a test based on QEMU to run Xen, Dom0 and start a DomU.
This is similar to the existing qemu-alpine-arm64.sh script and test.
The only differences are:
- use Debian's qemu-system-x86_64 (on ARM we build our own)
- use ipxe instead of u-boot and ImageBuilder

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
2021-10-29 16:23:26 -07:00
Stefano Stabellini d07af6949f automation: Linux 5.10.74 test-artifact
Build a 5.10 kernel to be used as Dom0 and DomU kernel for testing. This
is almost the same as the existing ARM64 recipe for Linux 5.9, the
only differences are:
- upgrade to latest 5.10.x stable
- force Xen modules to built-in (on ARM it was already done by defconfig)

Also add the exporting job to build.yaml so that the binary can be used
during gitlab-ci runs.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
2021-10-29 16:23:26 -07:00
Stefano Stabellini 69157cf82f automation: add x86_64 alpine 3.12 test-artifact
It is the same as the existing ARM64 alpine 3.12 test-artifact. It is
used to export an Alpine rootfs for Dom0 used for testing.

Also add the exporting job to build.yaml so that the binaries can be
used during gitlab-ci runs.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
2021-10-29 16:23:26 -07:00
Stefano Stabellini ec0648db75 xen: add (EXPERT) to one-line description of XEN_SHSTK
Add an "(EXPERT)" tag to the one-line description of Kconfig options
that depend on EXPERT. (Not where just the prompt depends on EXPERT.)

Today we only have one such option: XEN_SHSTK.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
CC: andrew.cooper3@citrix.com
CC: george.dunlap@citrix.com
CC: iwj@xenproject.org
CC: jbeulich@suse.com
CC: julien@xen.org
CC: wl@xen.org
2021-01-28 16:34:02 -08:00
Stefano Stabellini d96e5e6c12 xen: EXPERT clean-up and introduce UNSUPPORTED
A recent thread [1] has exposed a couple of issues with our current way
of handling EXPERT.

1) It is not obvious that "Configure standard Xen features (expert
users)" is actually the famous EXPERT we keep talking about on xen-devel

2) It is not obvious when we need to enable EXPERT to get a specific
feature

In particular if you want to enable ACPI support so that you can boot
Xen on an ACPI platform, you have to enable EXPERT first. But searching
through the kconfig menu it is really not clear (type '/' and "ACPI"):
nothing in the description tells you that you need to enable EXPERT to
get the option.

So this patch makes things easier by doing two things:

- introduce a new kconfig option UNSUPPORTED which is clearly to enable
  UNSUPPORTED features as defined by SUPPORT.md

- change EXPERT options to UNSUPPORTED where it makes sense: keep
  depending on EXPERT for features made for experts

- tag unsupported features by adding (UNSUPPORTED) to the one-line
  description

- clarify the EXPERT one-line description

[1] https://marc.info/?l=xen-devel&m=160333101228981

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com> [x86,common]
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
CC: andrew.cooper3@citrix.com
CC: george.dunlap@citrix.com
CC: iwj@xenproject.org
CC: jbeulich@suse.com
CC: julien@xen.org
CC: wl@xen.org
2021-01-28 16:34:01 -08:00
Stefano Stabellini c5f8e7d613 automation: add alpine linux arm64 build test
Based on the arm64 3.12 build container

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Acked-by: Wei Liu <wl@xen.org>
2020-12-17 14:56:43 -08:00
Stefano Stabellini 335ddd8ff6 automation: add alpine linux 3.12 arm64 build container
The build container will be used for a new Alpine Linux 3.12 arm64 build
test.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Acked-by: Wei Liu <wl@xen.org>
2020-12-17 14:56:43 -08:00