Re: [Xen-devel] [PATCH v2 13/16] x86: rearrange x86_64/entry.S

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.10.18 at 16:28, <wei.liu2@xxxxxxxxxx> wrote:
> @@ -845,19 +865,7 @@ handle_ist_exception:
>          /* We want to get straight to the IRET on the NMI exit path. */
>          testb $3,UREGS_cs(%rsp)
>          jz    restore_all_xen
> -        GET_CURRENT(bx)
> -        /* Send an IPI to ourselves to cover for the lack of event checking. 
> */
> -        movl  VCPU_processor(%rbx),%eax
> -        shll  $IRQSTAT_shift,%eax
> -        leaq  irq_stat+IRQSTAT_softirq_pending(%rip),%rcx
> -        cmpl  $0,(%rcx,%rax,1)
> -        je    1f
> -        movl  $EVENT_CHECK_VECTOR,%edi
> -        call  send_IPI_self
> -1:      movq  VCPU_domain(%rbx),%rax
> -        cmpb  $0,DOMAIN_is_32bit_pv(%rax)
> -        je    restore_all_guest
> -        jmp   compat_restore_all_guest
> +        jmp   self_ipi_restore_all_guest

I'm having some trouble understanding why you move this code:
Without CONFIG_PV it is unreachable. I'd prefer if it stayed in
place and simply got an #ifdef around it. The one alternative
option I could see is to move the restore_all_xen code block
right here, so the JMP you put in could become JNZ.

Jan



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