>-----Original Message-----
>From: Eric Auger <eric.au...@redhat.com>
>Subject: Re: [PATCH v2 09/19] intel_iommu: Introduce two helpers
>vtd_as_from/to_iommu_pasid_locked
>
>Hi Zhenzhong,
>
>On 6/20/25 9:18 AM, 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 9d4adc9458..8948b8370f 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 inline int vtd_as_to_iommu_pasid_locked(VTDAddressSpace *vtd_as,
>> + uint32_t *pasid)
>Is it meaningful to use inline here and below? Below I guess you do so
>to avoid "defined but not used" compilation error but I don't think it
>should stay as is.
Yes, that's the only reason I define the both inline.
Do you have other suggestions to avoid compilation error if not use inline?
>
>I don't really understand the iommu_pasid terminology. Either it is a
>pasid passed through the PCI transaction or it is the default pasid
>found in rid2passid ce field. So that's a pasid both ways ;-) can't you
>simply call it pasid.
Yes, PCI side we call it just pasid, the other side I name it iommu pasid to
distinguish.
Does that work for you?
>> +{
>> + 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;
>> + }
>> + }
>if the above pattern is used at many locations I still think it may be
>valuable to have a _locked helper.
Not get, both vtd_as_to_iommu_pasid_locked() and
vtd_as_from_iommu_pasid_locked()
are already _locked helper, isn't it?
Do you mean adding a comment saying "Caller of this function should hold
iommu_lock."
>> +
>> + /* Translate to iommu pasid if PCI_NO_PASID */
>> + if (vtd_as->pasid == PCI_NO_PASID) {
>> + *pasid = VTD_CE_GET_RID2PASID(&ce);
>> + } else {
>> + *pasid = vtd_as->pasid;
>> + }
>> +
>> + 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;
>why target? can't you name it key instead?
There is already a parameter named key, maybe target_key?
Thanks
Zhenzhong
>> + 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 */
>same here
>> +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)
>> {
>Thanks
>
>Eric
