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Fri, 7 Aug 2020 18:11:02 +0000 (UTC) Date: Fri, 7 Aug 2020 20:11:00 +0200 From: Igor Mammedov To: Babu Moger Subject: Re: [PATCH v3 1/3] i386: Simplify CPUID_8000_001E for AMD Message-ID: <20200807201100.5c141fe4@redhat.com> In-Reply-To: <159681796533.9679.8403552849052625336.stgit@naples-babu.amd.com> References: <159681772267.9679.1334429994189974662.stgit@naples-babu.amd.com> <159681796533.9679.8403552849052625336.stgit@naples-babu.amd.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=imammedo@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.120; envelope-from=imammedo@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/07 02:21:37 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, pbonzini@redhat.com, mst@redhat.com, ehabkost@redhat.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, 07 Aug 2020 11:32:45 -0500 Babu Moger wrote: > apic_id contains all the information required to build CPUID_8000_001E. > Also remove the restriction on number bits on core_id and node_id. > Remove all the hardcoded values and replace with generalized > fields. > > Refer the Processor Programming Reference (PPR) documentation > available from the bugzilla Link below. > > Signed-off-by: Babu Moger Reviewed-by: Igor Mammedov > --- > target/i386/cpu.c | 77 +++++++++++++++++++++++++---------------------------- > 1 file changed, 36 insertions(+), 41 deletions(-) > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index 588f32e136..c892432cae 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -388,57 +388,52 @@ static void encode_topo_cpuid8000001e(X86CPUTopoInfo *topo_info, X86CPU *cpu, > { > X86CPUTopoIDs topo_ids = {0}; > unsigned long nodes = MAX(topo_info->nodes_per_pkg, 1); > - int shift; > > x86_topo_ids_from_apicid_epyc(cpu->apic_id, topo_info, &topo_ids); > > *eax = cpu->apic_id; > + > /* > + * CPUID_Fn8000001E_EBX [Core Identifiers] (CoreId) > + * Read-only. Reset: 0000_XXXXh. > + * See Core::X86::Cpuid::ExtApicId. > + * Core::X86::Cpuid::CoreId_lthree[1:0]_core[3:0]_thread[1:0]; > * CPUID_Fn8000001E_EBX > - * 31:16 Reserved > - * 15:8 Threads per core (The number of threads per core is > - * Threads per core + 1) > - * 7:0 Core id (see bit decoding below) > - * SMT: > - * 4:3 node id > - * 2 Core complex id > - * 1:0 Core id > - * Non SMT: > - * 5:4 node id > - * 3 Core complex id > - * 1:0 Core id > + * Bits Description > + * 31:16 Reserved. > + * 15:8 ThreadsPerCore: threads per core. Read-only. Reset: XXh. > + * The number of threads per core is ThreadsPerCore+1. > + * 7:0 CoreId: core ID. Read-only. Reset: XXh. > + * > + * NOTE: CoreId is already part of apic_id. Just use it. We can > + * use all the 8 bits to represent the core_id here. > */ > - *ebx = ((topo_info->threads_per_core - 1) << 8) | (topo_ids.node_id << 3) | > - (topo_ids.core_id); > + *ebx = ((topo_info->threads_per_core - 1) << 8) | (topo_ids.core_id & 0xFF); > + > /* > + * CPUID_Fn8000001E_ECX [Node Identifiers] (NodeId) > + * Read-only. Reset: 0000_0XXXh. > + * Core::X86::Cpuid::NodeId_lthree[1:0]_core[3:0]_thread[1:0]; > * CPUID_Fn8000001E_ECX > - * 31:11 Reserved > - * 10:8 Nodes per processor (Nodes per processor is number of nodes + 1) > - * 7:0 Node id (see bit decoding below) > - * 2 Socket id > - * 1:0 Node id > + * Bits Description > + * 31:11 Reserved. > + * 10:8 NodesPerProcessor: Node per processor. Read-only. Reset: XXXb. > + * ValidValues: > + * Value Description > + * 000b 1 node per processor. > + * 001b 2 nodes per processor. > + * 010b Reserved. > + * 011b 4 nodes per processor. > + * 111b-100b Reserved. > + * 7:0 NodeId: Node ID. Read-only. Reset: XXh. > + * > + * NOTE: Hardware reserves 3 bits for number of nodes per processor. > + * But users can create more nodes than the actual hardware can > + * support. To genaralize we can use all the upper 8 bits for nodes. > + * NodeId is combination of node and socket_id which is already decoded > + * in apic_id. Just use it by shifting. > */ > - if (nodes <= 4) { > - *ecx = ((nodes - 1) << 8) | (topo_ids.pkg_id << 2) | topo_ids.node_id; > - } else { > - /* > - * Node id fix up. Actual hardware supports up to 4 nodes. But with > - * more than 32 cores, we may end up with more than 4 nodes. > - * Node id is a combination of socket id and node id. Only requirement > - * here is that this number should be unique accross the system. > - * Shift the socket id to accommodate more nodes. We dont expect both > - * socket id and node id to be big number at the same time. This is not > - * an ideal config but we need to to support it. Max nodes we can have > - * is 32 (255/8) with 8 cores per node and 255 max cores. We only need > - * 5 bits for nodes. Find the left most set bit to represent the total > - * number of nodes. find_last_bit returns last set bit(0 based). Left > - * shift(+1) the socket id to represent all the nodes. > - */ > - nodes -= 1; > - shift = find_last_bit(&nodes, 8); > - *ecx = (nodes << 8) | (topo_ids.pkg_id << (shift + 1)) | > - topo_ids.node_id; > - } > + *ecx = ((nodes - 1) << 8) | cpu->node_id; > *edx = 0; > } > > >