Re: [PATCH v4 1/2] docs: fusa: Define the requirements for XEN_VERSION hypercall.

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi Ayan,

> On 19 Aug 2025, at 13:27, Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx> wrote:
> 
> Define the requirements which are common for all the commands.
> 
> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>

Looks good

Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>

Cheers
Bertrand

> ---
> Changes from -
> 
> v1 - 1. Fixed `XenProd~version_hyp_ret_val~1` requirement as Xen does not 
> return
> 0 for success in all the cases.
> 2. Reworded the requirements so as to write them from Xen's perspective (not
> domain's perspective).
> 
> v2 - 1. Specified the register details.
> 2. Specified the type of buffer.
> 
> v3 - Fixed some wordings to make it precise (eg register details, bit fields).
> 
> .../fusa/reqs/design-reqs/arm64/hypercall.rst | 60 +++++++++++++++++++
> docs/fusa/reqs/index.rst                      |  2 +
> docs/fusa/reqs/market-reqs/reqs.rst           | 16 +++++
> .../reqs/product-reqs/version_hypercall.rst   | 42 +++++++++++++
> 4 files changed, 120 insertions(+)
> create mode 100644 docs/fusa/reqs/design-reqs/arm64/hypercall.rst
> create mode 100644 docs/fusa/reqs/product-reqs/version_hypercall.rst
> 
> diff --git a/docs/fusa/reqs/design-reqs/arm64/hypercall.rst 
> b/docs/fusa/reqs/design-reqs/arm64/hypercall.rst
> new file mode 100644
> index 0000000000..82ecf690a3
> --- /dev/null
> +++ b/docs/fusa/reqs/design-reqs/arm64/hypercall.rst
> @@ -0,0 +1,60 @@
> +.. SPDX-License-Identifier: CC-BY-4.0
> +
> +Hypercall
> +=========
> +
> +Instruction
> +-----------
> +
> +`XenSwdgn~arm64_hyp_instr~1`
> +
> +Description:
> +Xen shall treat domain hvc instruction execution (with 0xEA1) as hypercall
> +requests.
> +
> +Rationale:
> +
> +Comments:
> +Hypercall is one of the communication mechanism between Xen and domains.
> +Domains use hypercalls for various requests to Xen.
> +The exception syndrome register should have the following values :-
> +ESR_EL2.ISS should be 0xEA1.
> +ESR_EL2.EC should be 0x16.
> +
> +Covers:
> + - `XenProd~version_hyp_first_param~1`
> + - `XenProd~version_hyp_second_param~1`
> +
> +Parameters
> +----------
> +
> +`XenSwdgn~arm64_hyp_param~1`
> +
> +Description:
> +Xen shall use x0 - x4 core registers to obtain the arguments for domain 
> hypercall
> +requests.
> +
> +Rationale:
> +
> +Comments:
> +Xen shall read x0 for the first argument, x1 for the second argument and so 
> on.
> +
> +Covers:
> + - `XenProd~version_hyp_first_param~1`
> + - `XenProd~version_hyp_second_param~1`
> +
> +Hypercall number
> +----------------
> +
> +`XenSwdgn~arm64_hyp_num~1`
> +
> +Description:
> +Xen shall read x16 to obtain the hypercall number.
> +
> +Rationale:
> +
> +Comments:
> +
> +Covers:
> + - `XenProd~version_hyp_first_param~1`
> + - `XenProd~version_hyp_second_param~1`
> diff --git a/docs/fusa/reqs/index.rst b/docs/fusa/reqs/index.rst
> index 1088a51d52..d8683edce7 100644
> --- a/docs/fusa/reqs/index.rst
> +++ b/docs/fusa/reqs/index.rst
> @@ -10,5 +10,7 @@ Requirements documentation
>    market-reqs/reqs
>    product-reqs/reqs
>    product-reqs/arm64/reqs
> +   product-reqs/version_hypercall
>    design-reqs/arm64/generic-timer
>    design-reqs/arm64/sbsa-uart
> +   design-reqs/arm64/hypercall
> diff --git a/docs/fusa/reqs/market-reqs/reqs.rst 
> b/docs/fusa/reqs/market-reqs/reqs.rst
> index 2d297ecc13..7e3912c8f8 100644
> --- a/docs/fusa/reqs/market-reqs/reqs.rst
> +++ b/docs/fusa/reqs/market-reqs/reqs.rst
> @@ -79,3 +79,19 @@ Comments:
> 
> Needs:
>  - XenProd
> +
> +Version hypercall
> +-----------------
> +
> +`XenMkt~version_hypercall~1`
> +
> +Description:
> +Xen shall provide a hypercall for the domains to retrieve Xen's version, type
> +and compilation information.
> +
> +Rationale:
> +
> +Comments:
> +
> +Needs:
> + - XenProd
> diff --git a/docs/fusa/reqs/product-reqs/version_hypercall.rst 
> b/docs/fusa/reqs/product-reqs/version_hypercall.rst
> new file mode 100644
> index 0000000000..b824c539b0
> --- /dev/null
> +++ b/docs/fusa/reqs/product-reqs/version_hypercall.rst
> @@ -0,0 +1,42 @@
> +.. SPDX-License-Identifier: CC-BY-4.0
> +
> +Version hypercall
> +=================
> +
> +First Parameter
> +---------------
> +
> +`XenProd~version_hyp_first_param~1`
> +
> +Description:
> +Xen shall treat the value stored in x0 as the command number for the 
> hypercall.
> +
> +Rationale:
> +
> +Comments:
> +
> +Covers:
> + - `XenMkt~version_hypercall~1`
> +
> +Needs:
> + - XenSwdgn
> +
> +Second Parameter
> +----------------
> +
> +`XenProd~version_hyp_second_param~1`
> +
> +Description:
> +Xen shall treat the value stored in x1 as a domain virtual address (mapped as
> +Normal Inner Write-Back Outer Write-Back Inner-Shareable) to buffer in 
> domain's
> +memory.
> +
> +Rationale:
> +
> +Comments:
> +
> +Covers:
> + - `XenMkt~version_hypercall~1`
> +
> +Needs:
> + - XenSwdgn
> -- 
> 2.25.1
>