Re: [PATCH v2 03/39] xen/riscv: set the guest's XLEN explicitly in hstatus.VSXL

[Jan Beulich <jbeulich@xxxxxxxx>]

On 02.09.2026 15:29, Oleksii Kurochko wrote:
> On 9/2/26 3:07 PM, Jan Beulich wrote:
>> On 02.09.2026 13:42, Oleksii Kurochko wrote:
>>> It will also affect then common code as vcpu_csr_init() could be then
>>> called before domain type is set:
>>>
>>> +++ b/xen/common/device-tree/dom0less-build.c
>>> @@ -812,17 +812,18 @@ static int __init construct_domU(struct
>>> kernel_info *kinfo,
>>>        else if ( rc == 0 && !strcmp(dom0less_enhanced, "no-xenstore") )
>>>            kinfo->dom0less_feature = DOM0LESS_ENHANCED_NO_XS;
>>>
>>> -    if ( vcpu_create(d, 0) == NULL )
>>> -        return -ENOMEM;
>>> -
>>>        d->max_pages = ((paddr_t)mem * SZ_1K) >> PAGE_SHIFT;
>>>
>>>        rc = kernel_probe(kinfo, node);
>>>        if ( rc < 0 )
>>>            return rc;
>>>
>>> +    /* The domain type needs to be known before the first vCPU is
>>> created. */
>>>        set_domain_type(d, kinfo);
>>>
>>> +    if ( vcpu_create(d, 0) == NULL )
>>> +        return -ENOMEM;
>>
>> I don't understand the need for this, likely because I don't see why
>> domain_vsxl() would need calling from underneath vcpu_create().
> 
> The call trace will be the following:
>    vcpu_create() -> arch_vcpu_create() -> vcpu_csr_init() -> 
> domain_vsxldomain_vsxl()
> 
>      unsigned int vsxl = domain_vsxl(v->domain);
> 
>      ...
> 
>      vcpu_guest_cpu_user_regs(v)->hstatus =
>          HSTATUS_SPV | HSTATUS_SPVP | MASK_INSR(vsxl, HSTATUS_VSXL);
> 
> Without moving vcpu_create(d, 0) after set_domain_type(), domain_vsxl() 
> will return something wrong.

Question is - do you need to set ->hstatus this early?

> I also thought about updating of VSXL for each vCPU in 
> construct_domain() where d->type is already known and then no changes in 
> common code are needed. But I think it is a little bit better just have 
> a change in common code.

If the maintainers accept that change, it certainly may end up being easier.

Jan