Re: [Qemu-devel] [PATCH v4 13/13] pc: require IRQ remapping and EIM if there could be x2APIC CPUs

[Eduardo Habkost]

On Fri, Oct 14, 2016 at 01:25:35PM +0200, Igor Mammedov wrote:
> it would prevent starting guest with incorrect configs
> where interrupts couldn't be delivered to CPUs with
> APIC IDs > 255.
> 
> Signed-off-by: Igor Mammedov <address@hidden>
> Reviewed-by: Radim Krčmář <address@hidden>
> ---
> v4:
>  - s/254/255/ in commit message (Radim)
> ---
>  hw/i386/pc.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 40eb43b..f7070e0 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -68,6 +68,7 @@
>  #include "qapi-visit.h"
>  #include "qom/cpu.h"
>  #include "hw/nmi.h"
> +#include "hw/i386/intel_iommu.h"
>  
>  /* debug PC/ISA interrupts */
>  //#define DEBUG_IRQ
> @@ -1264,6 +1265,18 @@ void pc_machine_done(Notifier *notifier, void *data)
>                              sizeof(pcms->boot_cpus_le));
>          }
>      }
> +
> +    if (pcms->apic_id_limit > 255) {
> +        IntelIOMMUState *iommu = INTEL_IOMMU_DEVICE(x86_iommu_get_default());
> +
> +        if (!iommu || !iommu->x86_iommu.intr_supported ||
> +            iommu->intr_eim != ON_OFF_AUTO_ON) {
> +            error_report("current -smp configuration requires "
> +                         "Extended Interrupt Mode enabled. "
> +                         "IOMMU should have eim=on option set");

Suggestion for a follow-up patch:

* Error message explaining how to set eim=on if the iommu is
  available
* Error message explaining how to make sure the iommu is created,
  in case it was not even created.

-- 
Eduardo