Add support of Xen PV console via UART-like driver #36691

firscity · 2021-07-02T10:31:22Z

This commit series adds initial items for Xen features development (some of public headers, hypercall interface etc).

Also it adds minimal implementation of Xen PV console in Zephyr (via UART-like driver with poll API). It allows to get boot log and application stdout directly from domain hypervisor console, instead of emulated PL011 SBSA.

As addition, this console also supports console_io interface. It can be used for early boot log - driver introduces printk/stdout char-based hooks, that allow to receive kernel messages quickly after start, but require debug version of Xen (compiled with CONFIG_DEBUG option).

Fixes #37239

bertrand-marquis

Xen 4.16 is not release yet so if you took current headers status they might change before the 4.16 release in 6 month or so.
I would suggest to use a stable release when importing public headers (4.15.0)

bertrand-marquis · 2021-07-02T13:28:02Z

boards/arm64/xenvm/doc/index.rst

@@ -88,13 +77,17 @@ configuration would not boot on your hardware. In this case you need to update
 configuration by altering device tree and Kconfig options. This will be covered
 in detail in next section.

-No Xen-specific features are supported at the moment. This includes:
+Most of Xen-specific features are supported at the moment. This includes:


This changes looks weird.
Most of the features listed after are under development or not supported at all (xenbus for example).
More then that is is incoherent with the next chapter saying "now only following feature are supported".
Could this change be a mistake ?

Oh, sorry, agree. I missed "not" and context was broken. Of course, these feature are NOT supported yet.

Thank you for careful review!

firscity · 2021-07-02T14:21:13Z

Xen 4.16 is not release yet so if you took current headers status they might change before the 4.16 release in 6 month or so.
I would suggest to use a stable release when importing public headers (4.15.0)

I agree, did not pay enough attention for that. Xen public headers did not pass Zephyr code style and license check, so I decided to fix it altogether with your suggestion. Current headers were taken from Xen RELEASE-4.15.0 branch and modified to comply with Zephyr code-style.

Thank you for comment!

firscity · 2021-07-02T19:09:26Z

I need someone, who can clarify me few moment with Zephyr CI checks. The only 2 problems left in this PR according to CI report:

2 spacing errors in macro definition :

-:852: ERROR:SPACING: need consistent spacing around '*' (ctx:WxV)
852: FILE: include/xen/public/arch-arm.h:177:
+	typedef union { type *p; unsigned long q; }	\

It looks like style checker identify it as multiplication instead of pointer definition and produce spacing error (false-positive).

Licensing. Is it allowed to use MIT-licensed headers in Apache 2.0 Zephyr?
CI checker marked such headers as errors:

Error: * scan/include/xen/public/arch-arm.h is not apache-2.0 licensed: mit
* scan/include/xen/public/event_channel.h is not apache-2.0 licensed: mit
...

But as I can see, MIT headers/files are already present in Zephyr tree (e.g. include/net/http_parser.h). Is it possible to use original Xen public headers or I should create my own Apache 2.0 licensed files?

drivers/serial/Kconfig.xen

drivers/serial/uart_hvc_xen.c

carlocaione · 2021-07-03T07:22:15Z

One think I don't like is that we now have arch/arm64/xen when the proper place for this should be arch/arm64/core/xen if we want to follow what all archs are doing.

firscity · 2021-07-05T08:42:39Z

One think I don't like is that we now have arch/arm64/xen when the proper place for this should be arch/arm64/core/xen if we want to follow what all archs are doing.

Fixed, hypercall interface moved to arch/arm64/core/xen.

dcpleung · 2021-07-23T17:53:38Z

I think first step is to send a quick email to TSC mailing list about the licensing. Hopefully it would be easy since it's BSD.

carlescufi · 2021-08-16T12:10:05Z

@firscity sorry for the delay. I've included this in this week's TSC agenda.

firscity · 2021-08-16T15:32:08Z

@carlescufi, thank you a lot for help, I will wait for results. In case of TSC approval, I will prepare this PR for merge ASAP (fix merge conflicts).

cfriedt · 2021-09-07T17:28:05Z

@firscity - please rebase

firscity · 2021-09-08T05:05:31Z

@cfriedt, done.

cfriedt · 2021-09-09T00:22:44Z

@firscity - the TSC has decided to hold off merging this, but I would imagine it will go in in the near future. Thanks for your patience.

firscity · 2021-09-16T14:59:05Z

In 2.7 release CONFIG_UART_CONSOLE_ON_DEV_NAME Kconfig option was removed, so it was needed to change this PR a bit. This option was removed from xenvm_defconfig and console selection was moved to chosen device-tree node.

No functional changes were made by last force-push.

firscity · 2021-10-27T07:56:02Z

Is there any update for this pull request? Or v3.0.0 PRs are not ready for merge now?

carlocaione · 2021-10-27T09:02:23Z

Is there any update for this pull request? Or v3.0.0 PRs are not ready for merge now?

you need to rebase and fix the CI errors.

firscity · 2021-10-27T15:37:16Z

@carlocaione, done, failed CI tests are licensing and format false positives (described in comments above).

carlescufi · 2021-10-28T13:33:50Z

@firscity can you please rebase and solve the conflicts?

This commit adds few Xen public headers, which are needed for further development of Xen features in Zephyr. Headers were taken from include/public directory of Xen RELEASE-4.15.0 branch, filtered and cleaned up to leave only parts, which are now required. Directory structure were saved (public, public/io, public/hvm), so public headers content can be supplemented if nessesary. Signed-off-by: Dmytro Firsov <dmytro_firsov@epam.com>

This commit adds Xen hypervisor call interface for arm64 architecture. This is needed for further development of Xen features in Zephyr. Signed-off-by: Dmytro Firsov <dmytro_firsov@epam.com>

This commit adds minimal support of Xen hypervisor console via UART-like driver. Implementation allows to use poll_in/poll_out char interface for uart_console.c driver directly to HV console instead of using Xen virtual PL011 UART. Future implementation will support interrupt driven interface on Xen event channels, currently it is under development. Also this commit introduces early console_io Xen interface, which allows to receive printk/stdout messages quickly after start, but requires Xen, built with CONFIG_DEBUG option. Signed-off-by: Dmytro Firsov <dmytro_firsov@epam.com>

This commit removes usage of Xen emulated PL011 SBSA UART in favor of Xen PV console minimal implementation. Now boot log and application output can be directly taken from hypervisor domain console, instead of virtual UART. Also Xen VM doc was updated according to these changes. Signed-off-by: Dmytro Firsov <dmytro_firsov@epam.com>

firscity · 2021-10-28T16:48:16Z

@carlescufi yes, sure. Done.

firscity requested review from carlescufi, carlocaione, galak, MaureenHelm and nashif as code owners July 2, 2021 10:31

github-actions bot added area: API Changes to public APIs area: ARM64 ARM (64-bit) Architecture area: Boards area: Devicetree area: Documentation labels Jul 2, 2021

bertrand-marquis suggested changes Jul 2, 2021

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bertrand-marquis approved these changes Jul 2, 2021

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bertrand-marquis suggested changes Jul 2, 2021

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firscity force-pushed the xen_pvconsole_pr branch from 8f3db2e to 7e6e73d Compare July 2, 2021 14:15

bertrand-marquis approved these changes Jul 2, 2021

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firscity force-pushed the xen_pvconsole_pr branch 4 times, most recently from d3f1d0d to e37ca86 Compare July 2, 2021 16:08

carlocaione reviewed Jul 3, 2021

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carlocaione reviewed Jul 3, 2021

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firscity force-pushed the xen_pvconsole_pr branch from e37ca86 to a21b071 Compare July 5, 2021 08:39

firscity mentioned this pull request Jul 27, 2021

Initial Xen public headers adding #37239

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carlescufi requested a review from stephanosio August 16, 2021 12:07

firscity force-pushed the xen_pvconsole_pr branch from 8ca6c1d to 06a0efb Compare August 19, 2021 06:40

firscity force-pushed the xen_pvconsole_pr branch 2 times, most recently from e37ca86 to 8398ac4 Compare September 7, 2021 17:51

dcpleung approved these changes Sep 8, 2021

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nashif removed the TSC Topics that need TSC discussion label Sep 15, 2021

nashif added this to the v3.0.0 milestone Sep 15, 2021

firscity force-pushed the xen_pvconsole_pr branch from 8398ac4 to 14cf7d2 Compare September 16, 2021 14:55

firscity force-pushed the xen_pvconsole_pr branch from 14cf7d2 to 4651992 Compare September 16, 2021 15:07

firscity force-pushed the xen_pvconsole_pr branch from 4651992 to e1c5167 Compare October 27, 2021 10:05

firscity added 4 commits October 28, 2021 16:46

arm64: xenvm: Add Xen hypercall interface for arm64

35d6a5d

This commit adds Xen hypervisor call interface for arm64 architecture. This is needed for further development of Xen features in Zephyr. Signed-off-by: Dmytro Firsov <dmytro_firsov@epam.com>

firscity force-pushed the xen_pvconsole_pr branch from e1c5167 to 1066cc1 Compare October 28, 2021 13:49

carlescufi approved these changes Oct 29, 2021

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carlescufi merged commit 5451674 into zephyrproject-rtos:main Oct 29, 2021

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Add support of Xen PV console via UART-like driver #36691

Add support of Xen PV console via UART-like driver #36691

firscity commented Jul 2, 2021 •

edited by carlescufi

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Add support of Xen PV console via UART-like driver #36691

Add support of Xen PV console via UART-like driver #36691

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