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From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <ca9cd686-ea2f-716e-b909-f6e22d1c704c@redhat.com>
Date: Tue, 19 Dec 2017 12:12:35 +0100
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Subject: Re: [Qemu-devel] [PATCH qemu] RFC: spapr/iommu: Enable in-kernel
 TCE acceleration via VFIO KVM device
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To: Alex Williamson <alex.williamson@redhat.com>, Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: qemu-devel@nongnu.org, qemu-ppc@nongnu.org, David Gibson <david@gibson.dropbear.id.au>

On 12/12/2017 06:46, Alex Williamson wrote:
>> +enum IOMMUMemoryRegionAttr {
>> +    IOMMU_ATTR_KVM_FD
>=20
> You're generalizing the wrong thing here, this is specifically a
> SPAPR_TCE_FD, call it that.

... and you're not even implementing set_attr, so let's drop it.

My suggestion is to add a function in hw/vfio:

    int vfio_container_attach_kvm_spapr_tce(VFIOContainer *cont,
                                            int tablefd);

and an IOMMUMemoryRegionClass member:

    int (*set_vfio_container_attrs)(IOMMUMemoryRegion *iommu,
                                    VFIOContainer *cont)

Then your implementation for the latter is as simple as this:

    if (!kvm_enabled() || !kvmppc_has_cap_spapr_vfio()) {
        sPAPRTCETable *tcet =3D container_of(iommu, sPAPRTCETable, iommu)=
;
        return vfio_container_attach_kvm_spapr_tce(cont, tcet->fd);
    }

Thanks,

Paolo

>> +};
>> +
>>  typedef struct IOMMUMemoryRegionClass {
>>      /* private */
>>      struct DeviceClass parent_class;
>> @@ -210,6 +214,12 @@ typedef struct IOMMUMemoryRegionClass {
>>                                  IOMMUNotifierFlag new_flags);
>>      /* Set this up to provide customized IOMMU replay function */
>>      void (*replay)(IOMMUMemoryRegion *iommu, IOMMUNotifier *notifier)=
;
>> +
>> +    /* Get/set IOMMU misc attributes */
>> +    int (*get_attr)(IOMMUMemoryRegion *iommu, enum IOMMUMemoryRegionA=
ttr,
>> +                    void *data);
>> +    int (*set_attr)(IOMMUMemoryRegion *iommu, enum IOMMUMemoryRegionA=
ttr,
>> +                    void *data);