Re: [RFC PATCH V2 16/18] x86/sev: Initialize #HV doorbell and handle interrupt requests

[Tianyu Lan <ltykernel@gmail.com>]

On 11/21/2022 11:05 PM, Kalra, Ashish wrote:
>> +static void do_exc_hv(struct pt_regs *regs)
>> +{
>> +    union hv_pending_events pending_events;
>> +    u8 vector;
>> +
>> +    while (sev_hv_pending()) {
>> +        asm volatile("cli" : : : "memory");
>> +
> 
> Do we really need to disable interrupts here, #HV exception will be 
> dispatched via an interrupt gate in the IDT, so interrupts should be 
> implicitly disabled, right ?
>>    panic("Unexpected vector %d\n", vector);
>> +                unreachable();
>> +            }
>> +        } else {
>> +            common_interrupt(regs, pending_events.vector);
>> +        }
>> +
>> +        asm volatile("sti" : : : "memory");
> 
> Again, why do we need to re-enable interrupts here (in this loop), 
> interrupts will get re-enabled in the irqentry_exit() code path ?

Hi Ashish:
	Thanks for your review.	check_hv_pending() is also called in the
native_irq_enable() to handle some pending interrupt requests after re
-enabling interrupt. For such case, disables irq when handle exception
or interrupt event.