Re: [PATCH v2 01/16] xen/riscv: introduce struct arch_vcpu

[Jan Beulich <jbeulich@xxxxxxxx>]

On 22.01.2026 17:47, Oleksii Kurochko wrote:
> --- a/xen/arch/riscv/include/asm/domain.h
> +++ b/xen/arch/riscv/include/asm/domain.h
> @@ -22,9 +22,62 @@ struct hvm_domain
>  struct arch_vcpu_io {
>  };
>  
> -struct arch_vcpu {
> +struct arch_vcpu
> +{
>      struct vcpu_vmid vmid;
> -};
> +
> +    /*
> +     * Callee saved registers for Xen's state deep in the callframe used to
> +     * switch from prev's stack to the next's stack during context switch.
> +     */

What is "deep in the callframe" intended to convey? I'm in particular wondering
about ...

> +    struct
> +    {
> +        register_t s0;
> +        register_t s1;
> +        register_t s2;
> +        register_t s3;
> +        register_t s4;
> +        register_t s5;
> +        register_t s6;
> +        register_t s7;
> +        register_t s8;
> +        register_t s9;
> +        register_t s10;
> +        register_t s11;
> +        register_t sp;
> +        register_t gp;
> +        register_t ra;

... sp and ra, which presumably don't live anywhere "deep"?

Also, what about tp? The 't' in there isn't the same as that in "t0", "t1", etc.

> +    } xen_saved_context;
> +
> +    /* CSRs */
> +    register_t hedeleg;
> +    register_t hideleg;
> +    register_t hvip;
> +    register_t hip;
> +    register_t hie;
> +    register_t hgeie;
> +    register_t henvcfg;
> +    register_t hcounteren;
> +    register_t htimedelta;
> +    register_t htval;
> +    register_t htinst;
> +    register_t hstateen0;
> +#ifdef CONFIG_RISCV_32
> +    register_t henvcfgh;
> +    register_t htimedeltah;
> +#endif
> +
> +    /* VCSRs */

Why the V? These are normal CSRs dedicated to VS use, aren't they?

> +    register_t vsstatus;
> +    register_t vsip;
> +    register_t vsie;
> +    register_t vstvec;
> +    register_t vsscratch;
> +    register_t vscause;
> +    register_t vstval;
> +    register_t vsatp;
> +    register_t vsepc;
> +}  __cacheline_aligned;

I continue to question the presence of this attribute.

Jan