Re: [Xen-devel] [PATCH V3] vmx/nmi: Do not use self_nmi() in VMEXIT handler

[Tim Deegan <tim@xxxxxxx>]

At 15:00 +0000 on 22 Nov (1353596446), Andrew Cooper wrote:
> diff -r 2489c2926698 -r d7ea938044ac xen/arch/x86/hvm/vmx/vmx.c
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -2269,6 +2269,14 @@ void vmx_vmexit_handler(struct cpu_user_
>          vector = intr_info & INTR_INFO_VECTOR_MASK;
>          if ( vector == TRAP_machine_check )
>              do_machine_check(regs);
> +        else if ( vector == TRAP_nmi &&
> +                ( (intr_info & INTR_INFO_INTR_TYPE_MASK) ==
> +                  (X86_EVENTTYPE_NMI << 8) ) )
> +            /* Must be called before interrupts are enabled to ensure
> +             * the NMI handler code is run before the first IRET. The
> +             * IRET unblocks subsequent NMI's (Intel SDM Vol 3, 6.7.1)
> +             */
> +            do_nmi();
>          break;
>      case EXIT_REASON_MCE_DURING_VMENTRY:
>          do_machine_check(regs);

I think it might also make sense to move the HVMTARCE invocations that
are just above here down to after this block.  There's quite a lot of
code behind there and though I don't see any potential faults they might
well get added later (including in places like printk() and
tasklet_schedule()).

I had a look at the rest of the code that runs between the vmexit and
here, and it looks OK to me.

George, would that make the tracing more confusing?

Tim.


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