Re: [Qemu-devel] [PATCH v2 7/7] intel-iommu: keep buggy EIM enabled in 2.7 machine type

[Paolo Bonzini]

On 29/09/2016 13:23, Radim Krčmář wrote:
> QEMU 2.7 allowed EIM even in configurations that were forbidden in the
> last patch because they were not working, like old KVM or userspace
> APIC.  In order to keep backward compatibility, we again allow guests to
> misbehave in non-obvious ways, and make it the default.
> 
> Signed-off-by: Radim Krčmář <address@hidden>

Ugh, I misremembered that VTD_ECAP_EIM was not set in 2.7. :(  Perhaps
it's better to drop this patch...

Paolo

> ---
>  hw/i386/intel_iommu.c | 6 +++++-
>  hw/i386/pc_q35.c      | 2 ++
>  include/hw/i386/pc.h  | 2 ++
>  3 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index b1afe5b133e0..d6657a361ff9 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -2458,6 +2458,7 @@ static AddressSpace *vtd_host_dma_iommu(PCIBus *bus, 
> void *opaque, int devfn)
>  static void vtd_realize(DeviceState *dev, Error **errp)
>  {
>      PCMachineState *pcms = PC_MACHINE(qdev_get_machine());
> +    PCMachineClass *pcmc = PC_MACHINE_CLASS(MACHINE_GET_CLASS(pcms));
>      PCIBus *bus = pcms->bus;
>      IntelIOMMUState *s = INTEL_IOMMU_DEVICE(dev);
>      X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(dev);
> @@ -2481,11 +2482,14 @@ static void vtd_realize(DeviceState *dev, Error 
> **errp)
>      if (s->intr_eim == ON_OFF_AUTO_AUTO && !x86_iommu->intr_supported) {
>          s->intr_eim = ON_OFF_AUTO_OFF;
>      }
> +    if (s->intr_eim == ON_OFF_AUTO_AUTO && pcmc->buggy_intel_iommu_eim) {
> +        s->intr_eim = ON_OFF_AUTO_ON;
> +    }
>      if (s->intr_eim == ON_OFF_AUTO_AUTO) {
>          s->intr_eim = kvm_irqchip_in_kernel() ? ON_OFF_AUTO_ON
>                                                : ON_OFF_AUTO_OFF;
>      }
> -    if (s->intr_eim == ON_OFF_AUTO_ON) {
> +    if (s->intr_eim == ON_OFF_AUTO_ON && !pcmc->buggy_intel_iommu_eim) {
>          if (kvm_irqchip_in_kernel() && !kvm_enable_x2apic()) {
>              error_report("intel-iommu,eim=on requires support on the KVM 
> side "
>                           "(X2APIC_API, first shipped in v4.7).");
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 0b214f24c977..97f419fbf4dd 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -304,8 +304,10 @@ DEFINE_Q35_MACHINE(v2_8, "pc-q35-2.8", NULL,
>  
>  static void pc_q35_2_7_machine_options(MachineClass *m)
>  {
> +    PCMachineClass *pcmc = PC_MACHINE_CLASS(m);
>      pc_q35_2_8_machine_options(m);
>      m->alias = NULL;
> +    pcmc->buggy_intel_iommu_eim = true;
>      SET_MACHINE_COMPAT(m, PC_COMPAT_2_7);
>  }
>  
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 47bdf10cfd9b..4bd435f8fa5c 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -143,6 +143,8 @@ struct PCMachineClass {
>      bool save_tsc_khz;
>      /* generate legacy CPU hotplug AML */
>      bool legacy_cpu_hotplug;
> +    /* enable buggy Intel-IOMMU EIM by default */
> +    bool buggy_intel_iommu_eim;
>  };
>  
>  #define TYPE_PC_MACHINE "generic-pc-machine"
>