From nobody Sun Sep 28 15:58:41 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1756307449426995.392708932392; Wed, 27 Aug 2025 08:10:49 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1urHmi-0004jO-2S; Wed, 27 Aug 2025 11:10:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1urHjJ-0006k8-QY; Wed, 27 Aug 2025 11:06:31 -0400 Received: from isrv.corpit.ru ([212.248.84.144]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1urHjH-0005RL-Pm; Wed, 27 Aug 2025 11:06:29 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id BDA2314C54B; Wed, 27 Aug 2025 18:02:58 +0300 (MSK) Received: from think4mjt.tls.msk.ru (mjtthink.wg.tls.msk.ru [192.168.177.146]) by tsrv.corpit.ru (Postfix) with ESMTP id A6A09269853; Wed, 27 Aug 2025 18:03:25 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Chuang Xu , Zhao Liu , Guixiong Wei , Yipeng Yin , Paolo Bonzini , Michael Tokarev Subject: [Stable-10.0.4 35/59] i386/cpu: Fix number of addressable IDs field for CPUID.01H.EBX[23:16] Date: Wed, 27 Aug 2025 18:02:40 +0300 Message-ID: <20250827150323.2694101-35-mjt@tls.msk.ru> X-Mailer: git-send-email 2.47.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=212.248.84.144; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1756307450762116600 Content-Type: text/plain; charset="utf-8" From: Chuang Xu When QEMU is started with: -cpu host,migratable=3Don,host-cache-info=3Don,l3-cache=3Doff -smp 180,sockets=3D2,dies=3D1,cores=3D45,threads=3D2 On Intel platform: CPUID.01H.EBX[23:16] is defined as "max number of addressable IDs for logical processors in the physical package". When executing "cpuid -1 -l 1 -r" in the guest, we obtain a value of 90 for CPUID.01H.EBX[23:16], whereas the expected value is 128. Additionally, executing "cpuid -1 -l 4 -r" in the guest yields a value of 63 for CPUID.04H.EAX[31:26], which matches the expected result. As (1+CPUID.04H.EAX[31:26]) rounds up to the nearest power-of-2 integer, it's necessary to round up CPUID.01H.EBX[23:16] to the nearest power-of-2 integer too. Otherwise there would be unexpected results in guest with older kernel. For example, when QEMU is started with CLI above and xtopology is disabled, guest kernel 5.15.120 uses CPUID.01H.EBX[23:16]/(1+CPUID.04H.EAX[31:26]) to calculate threads-per-core in detect_ht(). Then guest will get "90/(1+63)= =3D1" as the result, even though threads-per-core should actually be 2. And on AMD platform: CPUID.01H.EBX[23:16] is defined as "Logical processor count". Current result meets our expectation. So round up CPUID.01H.EBX[23:16] to the nearest power-of-2 integer only for Intel platform to solve the unexpected result. Use the "x-vendor-cpuid-only-v2" compat option to fix this issue. Reviewed-by: Zhao Liu Signed-off-by: Guixiong Wei Signed-off-by: Yipeng Yin Signed-off-by: Chuang Xu Signed-off-by: Zhao Liu Link: https://lore.kernel.org/r/20250714080859.1960104-5-zhao1.liu@intel.com Signed-off-by: Paolo Bonzini (cherry picked from commit f985a1195ba2d9c6f6f33e83fe2e419a7e8acb60) (Mjt: this change refers to cpu->vendor_cpuid_only_v2 which is introduced after 10.0, but this reference is removed later. Replace it with false for now, so effectively this commit is a no-op, but prepares the code for the next change in this area and keeps historical references) Signed-off-by: Michael Tokarev diff --git a/target/i386/cpu.c b/target/i386/cpu.c index d3e3ca13ca..ed262edcc8 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -6835,7 +6835,17 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,= uint32_t count, } *edx =3D env->features[FEAT_1_EDX]; if (threads_per_pkg > 1) { - *ebx |=3D threads_per_pkg << 16; + /* + * For CPUID.01H.EBX[Bits 23-16], AMD requires logical process= or + * count, but Intel needs maximum number of addressable IDs for + * logical processors per package. + */ + if (/*10.0: cpu->vendor_cpuid_only_v2*/ false && + (IS_INTEL_CPU(env) || IS_ZHAOXIN_CPU(env))) { + *ebx |=3D 1 << apicid_pkg_offset(topo_info) << 16; + } else { + *ebx |=3D threads_per_pkg << 16; + } } break; case 2: --=20 2.47.2