>-----Original Message-----
>From: Liu, Yi L <yi.l.liu@intel.com>
>Subject: Re: [PATCH v5 10/21] intel_iommu: Introduce two helpers
>vtd_as_from/to_iommu_pasid_locked
>
>On 2025/8/22 14:40, 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.
>
>translate is somehow strange. convert or get might be better? Same to
>the translate terms in the patch.
OK, will use 'convert' terminology.
>
>>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>> Reviewed-by: Eric Auger <eric.auger@redhat.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 6edd91d94e..1801f1cdf6 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;
>> +
>> + /* For Requests-with-PASID, its pasid value is used by vIOMMU
>directly */
>> + if (vtd_as->pasid != PCI_NO_PASID) {
>> + *pasid = vtd_as->pasid;
>> + return 0;
>> + }
>> +
>> + 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;
>> + }
>> + }
>> + *pasid = VTD_CE_GET_RID2PASID(&ce);
>
>looks like we have quite a few code get rid_pasid from the context
>entry. I think we may simplify it by using PASID #0 since vIOMMU does
>not report ECAP.RPS bit at all. It could be done as a separate cleanup.
Yes, but we already have all code supporting RPS capability though RPS
isn't enabled in CAP register. In theory we can enable RPS easily by setting
the bit in CAP register. So I would like to be consistent with this instead of
dropping all the existing code about RPS cap.
Thanks
Zhenzhong
>
>> + return 0;
>> +}
>> +
>> +static gboolean vtd_find_as_by_sid_and_iommu_pasid(gpointer key,
>gpointer value,
>> + gpointer
>user_data)
>> +{
>> + VTDAddressSpace *vtd_as = (VTDAddressSpace *)value;
>> + struct vtd_as_raw_key *target = (struct vtd_as_raw_key *)user_data;
>> + uint16_t sid = PCI_BUILD_BDF(pci_bus_num(vtd_as->bus),
>vtd_as->devfn);
>> + uint32_t pasid;
>> +
>> + if (vtd_as_to_iommu_pasid_locked(vtd_as, &pasid)) {
>> + return false;
>> + }
>> +
>> + return (pasid == target->pasid) && (sid == target->sid);
>> +}
>> +
>> +/* Translate iommu pasid to vtd_as */
>> +static inline
>> +VTDAddressSpace *vtd_as_from_iommu_pasid_locked(IntelIOMMUState
>*s,
>> + uint16_t sid,
>uint32_t pasid)
>> +{
>> + struct vtd_as_raw_key key = {
>> + .sid = sid,
>> + .pasid = pasid
>> + };
>> +
>> + return g_hash_table_find(s->vtd_address_spaces,
>> + vtd_find_as_by_sid_and_iommu_pasid,
>&key);
>> +}
>> +
>> static int vtd_sync_shadow_page_hook(const IOMMUTLBEvent *event,
>> void *private)
>> {
>
>the code looks good to me.
>
>Reviewed-by: Yi Liu <yi.l.liu@intel.com>