Re: [PATCH v2 10/16] xen/riscv: add vtimer context switch helpers

[Oleksii Kurochko <oleksii.kurochko@gmail.com>]

On 2/3/26 5:43 PM, Jan Beulich wrote:
> On 22.01.2026 17:47, Oleksii Kurochko wrote:
>> Introduce vtimer_ctx_switch_from() and vtimer_ctx_switch_to() to handle
>> virtual timer state across vCPU context switches.
>>
>> At present, vtimer_ctx_switch_from() is a no-op because the RISC-V SSTC
>> extension, which provides a virtualization-aware timer, is not yet
>> supported. Xen therefore relies the virtual (SBI-based) timer.
>>
>> The virtual timer uses Xen's internal timer infrastructure and must be
>> associated with the pCPU on which the vCPU is currently running so that
>> timer events can be delivered efficiently. As a result, vtimer_ctx_switch_to()
>> migrates the timer to the target pCPU when a vCPU is scheduled in.
>>
>> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
> Acked-by: Jan Beulich <jbeulich@suse.com>

Thanks.

>
> However, ...
>
>> --- a/xen/arch/riscv/include/asm/vtimer.h
>> +++ b/xen/arch/riscv/include/asm/vtimer.h
>> @@ -17,4 +17,7 @@ void vcpu_timer_destroy(struct vcpu *v);
>>   
>>   void vtimer_set_timer(struct vtimer *t, uint64_t ticks);
>>   
>> +void vtimer_ctx_switch_from(struct vcpu *p);
>> +void vtimer_ctx_switch_to(struct vcpu *n);
> ... may I ask that you reconsider naming here? Both Arm and x86 have functions
> where the prefix / infix is "ctxt", not just "ctx". Being able to find all by
> grep-ing for e.g. ctxt_switch_from might be quite nice.

Sure, I will do that, it makes sense.

~ Oleksii