>-----Original Message-----
>From: Eric Auger <eric.au...@redhat.com>
>Subject: Re: [PATCH v3 09/20] intel_iommu: Introduce two helpers
>vtd_as_from/to_iommu_pasid_locked
>
>Hi Zhenzhong,
>
>On 7/8/25 1:05 PM, Zhenzhong Duan wrote:
>> PCI device supports two request types, Requests-without-PASID and
>> Requests-with-PASID. Requests-without-PASID doesn't include a PASID TLP
>> prefix, IOMMU fetches rid_pasid from context entry and use it as IOMMU's
>> pasid to index pasid table.
>>
>> So we need to translate between PCI's pasid and IOMMU's pasid specially
>> for Requests-without-PASID, e.g., PCI_NO_PASID(-1) <-> rid_pasid.
>> For Requests-with-PASID, PCI's pasid and IOMMU's pasid are same value.
>>
>> vtd_as_from_iommu_pasid_locked() translates from BDF+iommu_pasid to
>vtd_as
>> which contains PCI's pasid vtd_as->pasid.
>>
>> vtd_as_to_iommu_pasid_locked() translates from BDF+vtd_as->pasid to
>iommu_pasid.
>>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
>> ---
>> hw/i386/intel_iommu.c | 58
>+++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 58 insertions(+)
>>
>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
>> index 15f4393d6f..38e7f7b7be 100644
>> --- a/hw/i386/intel_iommu.c
>> +++ b/hw/i386/intel_iommu.c
>> @@ -1602,6 +1602,64 @@ static int
>vtd_dev_to_context_entry(IntelIOMMUState *s, uint8_t bus_num,
>> return 0;
>> }
>>
>> +static int vtd_as_to_iommu_pasid_locked(VTDAddressSpace *vtd_as,
>> + uint32_t *pasid)
>> +{
>> + VTDContextCacheEntry *cc_entry = &vtd_as->context_cache_entry;
>> + IntelIOMMUState *s = vtd_as->iommu_state;
>> + uint8_t bus_num = pci_bus_num(vtd_as->bus);
>> + uint8_t devfn = vtd_as->devfn;
>> + VTDContextEntry ce;
>> + int ret;
>> +
>> + if (cc_entry->context_cache_gen == s->context_cache_gen) {
>> + ce = cc_entry->context_entry;
>> + } else {
>> + ret = vtd_dev_to_context_entry(s, bus_num, devfn, &ce);
>> + if (ret) {
>> + return ret;
>you need to retrieve the ce only if vtd_as->pasid. So this can be moved
>to the conditional block below.
Good idea! Will do.
Thanks
Zhenzhong
