RE: [PATCH rfcv2 14/18] intel_iommu: Add a framework to check and sync host IOMMU cap/ecap

[Duan, Zhenzhong]

>-----Original Message-----
>From: Eric Auger <eric.auger@redhat.com>
>Subject: Re: [PATCH rfcv2 14/18] intel_iommu: Add a framework to check
>and sync host IOMMU cap/ecap
>
>
>
>On 2/1/24 08:28, Zhenzhong Duan wrote:
>> From: Yi Liu <yi.l.liu@intel.com>
>>
>> Add a framework to check and synchronize host IOMMU cap/ecap with
>> vIOMMU cap/ecap.
>>
>> The sequence will be:
>>
>> vtd_cap_init() initializes iommu->cap/ecap.
>> vtd_check_hdev() update iommu->cap/ecap based on host cap/ecap.
>> iommu->cap_frozen set when machine create done, iommu->cap/ecap
>become readonly.
>>
>> Implementation details for different backends will be in following patches.
>>
>> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
>> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>> ---
>>  include/hw/i386/intel_iommu.h |  1 +
>>  hw/i386/intel_iommu.c         | 41
>++++++++++++++++++++++++++++++++++-
>>  2 files changed, 41 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/hw/i386/intel_iommu.h
>b/include/hw/i386/intel_iommu.h
>> index bbc7b96add..c71a133820 100644
>> --- a/include/hw/i386/intel_iommu.h
>> +++ b/include/hw/i386/intel_iommu.h
>> @@ -283,6 +283,7 @@ struct IntelIOMMUState {
>>
>>      uint64_t cap;                   /* The value of capability reg */
>>      uint64_t ecap;                  /* The value of extended capability reg 
>> */
>> +    bool cap_frozen;                /* cap/ecap become read-only after 
>> frozen */
>>
>>      uint32_t context_cache_gen;     /* Should be in [1,MAX] */
>>      GHashTable *iotlb;              /* IOTLB */
>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
>> index ffa1ad6429..7ed2b79669 100644
>> --- a/hw/i386/intel_iommu.c
>> +++ b/hw/i386/intel_iommu.c
>> @@ -3819,6 +3819,31 @@ VTDAddressSpace
>*vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus,
>>      return vtd_dev_as;
>>  }
>>
>> +static int vtd_check_legacy_hdev(IntelIOMMUState *s,
>> +                                 IOMMULegacyDevice *ldev,
>> +                                 Error **errp)
>> +{
>> +    return 0;
>> +}
>> +
>> +static int vtd_check_iommufd_hdev(IntelIOMMUState *s,
>> +                                  IOMMUFDDevice *idev,
>> +                                  Error **errp)
>> +{
>> +    return 0;
>> +}
>> +
>> +static int vtd_check_hdev(IntelIOMMUState *s, VTDHostIOMMUDevice
>*vtd_hdev,
>> +                          Error **errp)
>> +{
>> +    HostIOMMUDevice *base_dev = vtd_hdev->dev;
>> +
>> +    if (base_dev->type == HID_LEGACY) {
>> +        return vtd_check_legacy_hdev(s, vtd_hdev->ldev, errp);
>> +    }
>> +    return vtd_check_iommufd_hdev(s, vtd_hdev->idev, errp);
>Couldn't we have HostIOMMUDevice ops instead of having this check here?

Hmm, not sure if this is deserved. If we define such ops, it has only one 
function
check_hdev and we still need to check base_dev->type to assign different
function to HostIOMMUDevice.ops.check_hdev in vtd_dev_set_iommu_device().

Thanks
Zhenzhong