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([2a01:e0a:f0e:9070:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47732fe1075sm18258325e9.11.2025.10.31.00.50.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 31 Oct 2025 00:50:43 -0700 (PDT) Message-ID: <4a46df94-76dc-4c4b-b05c-09ecad583f7c@redhat.com> Date: Fri, 31 Oct 2025 08:50:42 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 02/23] intel_iommu: Delete RPS capability related supporting code Content-Language: en-US To: Zhenzhong Duan , qemu-devel@nongnu.org Cc: alex.williamson@redhat.com, clg@redhat.com, mst@redhat.com, jasowang@redhat.com, peterx@redhat.com, ddutile@redhat.com, jgg@nvidia.com, nicolinc@nvidia.com, skolothumtho@nvidia.com, joao.m.martins@oracle.com, clement.mathieu--drif@eviden.com, kevin.tian@intel.com, yi.l.liu@intel.com, chao.p.peng@intel.com References: <20251024084349.102322-1-zhenzhong.duan@intel.com> <20251024084349.102322-3-zhenzhong.duan@intel.com> From: Eric Auger In-Reply-To: <20251024084349.102322-3-zhenzhong.duan@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: eric.auger@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi Zhenzhong, On 10/24/25 10:43 AM, Zhenzhong Duan wrote: > RID-PASID Support(RPS) is not set in vIOMMU ECAP register, the supporting > code is there but never takes effect. > > Meanwhile, according to VTD spec section 3.4.3: > "Implementations not supporting RID_PASID capability (ECAP_REG.RPS is 0b), > use a PASID value of 0 to perform address translation for requests without > PASID." > > We should delete the supporting code which fetches RID_PASID field from > scalable context entry and use 0 as RID_PASID directly, because RID_PASID > field is ignored if no RPS support according to spec. > > This simplifies the code and doesn't bring any penalty. > > Suggested-by: Yi Liu > Signed-off-by: Zhenzhong Duan > --- > hw/i386/intel_iommu_internal.h | 1 - > hw/i386/intel_iommu.c | 82 +++++++++++----------------------- > 2 files changed, 27 insertions(+), 56 deletions(-) > > diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h > index 75bafdf0cd..bf8fb2aa80 100644 > --- a/hw/i386/intel_iommu_internal.h > +++ b/hw/i386/intel_iommu_internal.h > @@ -609,7 +609,6 @@ typedef struct VTDRootEntry VTDRootEntry; > #define VTD_CTX_ENTRY_LEGACY_SIZE 16 > #define VTD_CTX_ENTRY_SCALABLE_SIZE 32 > > -#define VTD_SM_CONTEXT_ENTRY_RID2PASID_MASK 0xfffff > #define VTD_SM_CONTEXT_ENTRY_RSVD_VAL0(aw) (0x1e0ULL | ~VTD_HAW_MASK(aw)) > #define VTD_SM_CONTEXT_ENTRY_RSVD_VAL1 0xffffffffffe00000ULL > #define VTD_SM_CONTEXT_ENTRY_PRE 0x10ULL > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c > index 70746e3080..06065d16b6 100644 > --- a/hw/i386/intel_iommu.c > +++ b/hw/i386/intel_iommu.c > @@ -42,8 +42,7 @@ > #include "trace.h" > > /* context entry operations */ > -#define VTD_CE_GET_RID2PASID(ce) \ > - ((ce)->val[1] & VTD_SM_CONTEXT_ENTRY_RID2PASID_MASK) > +#define PASID_0 0 > #define VTD_CE_GET_PASID_DIR_TABLE(ce) \ > ((ce)->val[0] & VTD_PASID_DIR_BASE_ADDR_MASK) > #define VTD_CE_GET_PRE(ce) \ > @@ -963,7 +962,7 @@ static int vtd_ce_get_pasid_entry(IntelIOMMUState *s, VTDContextEntry *ce, > int ret = 0; while you are at it, get rid of ret and simply return vtd_get_pe_from_pasid_table()? > > if (pasid == PCI_NO_PASID) { > - pasid = VTD_CE_GET_RID2PASID(ce); > + pasid = PASID_0; > } > pasid_dir_base = VTD_CE_GET_PASID_DIR_TABLE(ce); > ret = vtd_get_pe_from_pasid_table(s, pasid_dir_base, pasid, pe); > @@ -982,7 +981,7 @@ static int vtd_ce_get_pasid_fpd(IntelIOMMUState *s, > VTDPASIDEntry pe; > > if (pasid == PCI_NO_PASID) { > - pasid = VTD_CE_GET_RID2PASID(ce); > + pasid = PASID_0; > } > pasid_dir_base = VTD_CE_GET_PASID_DIR_TABLE(ce); > > @@ -1522,17 +1521,15 @@ static inline int vtd_context_entry_rsvd_bits_check(IntelIOMMUState *s, > return 0; > } > > -static int vtd_ce_rid2pasid_check(IntelIOMMUState *s, > - VTDContextEntry *ce) > +static int vtd_ce_pasid_0_check(IntelIOMMUState *s, VTDContextEntry *ce) > { > VTDPASIDEntry pe; > > /* > * Make sure in Scalable Mode, a present context entry > - * has valid rid2pasid setting, which includes valid > - * rid2pasid field and corresponding pasid entry setting > + * has valid pasid entry setting at PASID_0. > */ > - return vtd_ce_get_pasid_entry(s, ce, &pe, PCI_NO_PASID); > + return vtd_ce_get_pasid_entry(s, ce, &pe, PASID_0); > } > > /* Map a device to its corresponding domain (context-entry) */ > @@ -1593,12 +1590,11 @@ static int vtd_dev_to_context_entry(IntelIOMMUState *s, uint8_t bus_num, > } > } else { > /* > - * Check if the programming of context-entry.rid2pasid > - * and corresponding pasid setting is valid, and thus > - * avoids to check pasid entry fetching result in future > - * helper function calling. > + * Check if the programming of pasid setting of PASID_0 > + * is valid, and thus avoids to check pasid entry fetching > + * result in future helper function calling. > */ > - ret_fr = vtd_ce_rid2pasid_check(s, ce); > + ret_fr = vtd_ce_pasid_0_check(s, ce); I guess you should be able to return vtd_ce_pasid_0_check(s, ce) directly too. > if (ret_fr) { > return ret_fr; > } > @@ -2110,7 +2106,6 @@ static bool vtd_do_iommu_translate(VTDAddressSpace *vtd_as, PCIBus *bus, > bool reads = true; > bool writes = true; > uint8_t access_flags, pgtt; > - bool rid2pasid = (pasid == PCI_NO_PASID) && s->root_scalable; > VTDIOTLBEntry *iotlb_entry; > uint64_t xlat, size; > > @@ -2122,21 +2117,23 @@ static bool vtd_do_iommu_translate(VTDAddressSpace *vtd_as, PCIBus *bus, > > vtd_iommu_lock(s); > > - cc_entry = &vtd_as->context_cache_entry; any reason why cc_entry setting was moved? Seems a spurious change. > + if (pasid == PCI_NO_PASID && s->root_scalable) { > + pasid = PASID_0; > + } > > - /* Try to fetch pte from IOTLB, we don't need RID2PASID logic */ > - if (!rid2pasid) { > - iotlb_entry = vtd_lookup_iotlb(s, source_id, pasid, addr); > - if (iotlb_entry) { > - trace_vtd_iotlb_page_hit(source_id, addr, iotlb_entry->pte, > - iotlb_entry->domain_id); > - pte = iotlb_entry->pte; > - access_flags = iotlb_entry->access_flags; > - page_mask = iotlb_entry->mask; > - goto out; > - } > + /* Try to fetch pte from IOTLB */ > + iotlb_entry = vtd_lookup_iotlb(s, source_id, pasid, addr); > + if (iotlb_entry) { > + trace_vtd_iotlb_page_hit(source_id, addr, iotlb_entry->pte, > + iotlb_entry->domain_id); > + pte = iotlb_entry->pte; > + access_flags = iotlb_entry->access_flags; > + page_mask = iotlb_entry->mask; > + goto out; > } > > + cc_entry = &vtd_as->context_cache_entry; > + > /* Try to fetch context-entry from cache first */ > if (cc_entry->context_cache_gen == s->context_cache_gen) { > trace_vtd_iotlb_cc_hit(bus_num, devfn, cc_entry->context_entry.hi, > @@ -2173,10 +2170,6 @@ static bool vtd_do_iommu_translate(VTDAddressSpace *vtd_as, PCIBus *bus, > cc_entry->context_cache_gen = s->context_cache_gen; > } > > - if (rid2pasid) { > - pasid = VTD_CE_GET_RID2PASID(&ce); > - } > - > /* > * We don't need to translate for pass-through context entries. > * Also, let's ignore IOTLB caching as well for PT devices. > @@ -2202,19 +2195,6 @@ static bool vtd_do_iommu_translate(VTDAddressSpace *vtd_as, PCIBus *bus, > return true; > } > > - /* Try to fetch pte from IOTLB for RID2PASID slow path */ > - if (rid2pasid) { > - iotlb_entry = vtd_lookup_iotlb(s, source_id, pasid, addr); > - if (iotlb_entry) { > - trace_vtd_iotlb_page_hit(source_id, addr, iotlb_entry->pte, > - iotlb_entry->domain_id); > - pte = iotlb_entry->pte; > - access_flags = iotlb_entry->access_flags; > - page_mask = iotlb_entry->mask; > - goto out; > - } > - } > - > if (s->flts && s->root_scalable) { > ret_fr = vtd_iova_to_flpte(s, &ce, addr, is_write, &pte, &level, > &reads, &writes, s->aw_bits, pasid); > @@ -2477,20 +2457,14 @@ static void vtd_iotlb_page_invalidate_notify(IntelIOMMUState *s, > ret = vtd_dev_to_context_entry(s, pci_bus_num(vtd_as->bus), > vtd_as->devfn, &ce); > if (!ret && domain_id == vtd_get_domain_id(s, &ce, vtd_as->pasid)) { > - uint32_t rid2pasid = PCI_NO_PASID; > - > - if (s->root_scalable) { > - rid2pasid = VTD_CE_GET_RID2PASID(&ce); > - } > - > /* > * In legacy mode, vtd_as->pasid == pasid is always true. > * In scalable mode, for vtd address space backing a PCI > * device without pasid, needs to compare pasid with > - * rid2pasid of this device. > + * PASID_0 of this device. > */ > if (!(vtd_as->pasid == pasid || > - (vtd_as->pasid == PCI_NO_PASID && pasid == rid2pasid))) { > + (vtd_as->pasid == PCI_NO_PASID && pasid == PASID_0))) { don't you need to check you are in s->root_scalable mode too? Thanks Eric > continue; > } > > @@ -2995,9 +2969,7 @@ static void vtd_piotlb_pasid_invalidate(IntelIOMMUState *s, > if (!vtd_dev_to_context_entry(s, pci_bus_num(vtd_as->bus), > vtd_as->devfn, &ce) && > domain_id == vtd_get_domain_id(s, &ce, vtd_as->pasid)) { > - uint32_t rid2pasid = VTD_CE_GET_RID2PASID(&ce); > - > - if ((vtd_as->pasid != PCI_NO_PASID || pasid != rid2pasid) && > + if ((vtd_as->pasid != PCI_NO_PASID || pasid != PASID_0) && > vtd_as->pasid != pasid) { > continue; > }