From nobody Sun Sep 28 15:30:17 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; 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; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1758624134; cv=none; d=zohomail.com; s=zohoarc; b=Xf2/8lIK6IQlCCLgUb2nzNiurXqOK4JZFgP5Q9nd471xIbKa7lO4oieojfw5zKcxCyftcibnm6K/FHwl7HSC4qF/cApKlXRRb5REmStt/oaqsIDAD9mJe6XSgctTlEDngg7EIPIi7JlD+K+Kkz22fhNC+4Vdt9yy1JhGxlmCGyE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1758624134; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=S7AvEaNloXl7AAmAS1Y5CI+jWkOoqizDLL87K4Tp+NY=; b=TRE3ITptWqvFKJ+HOvzj8eGXlIyq68jxIHRoFbFI9zM0geRpiZ3ykBbpQID23GVU2663XG87i7aGjmviE7AW6TYI8ow2NQWKajw1DJ49hP6cXCWjeMED7+8ipDmFeGuWt85Of/rlp+HpRtL25qoVaHLqZPuS6vyxQR9FamlFw64= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; 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; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1758624134191662.2444320506867; Tue, 23 Sep 2025 03:42:14 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v10T3-0004bb-8k; Tue, 23 Sep 2025 06:41:53 -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 1v10T1-0004Xd-J5 for qemu-devel@nongnu.org; Tue, 23 Sep 2025 06:41:51 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v10Sy-0006C1-OZ for qemu-devel@nongnu.org; Tue, 23 Sep 2025 06:41:51 -0400 Received: from mail-ej1-f72.google.com (mail-ej1-f72.google.com [209.85.218.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-692-53sgG4HMOW2R-9bmYnjv3Q-1; Tue, 23 Sep 2025 06:41:43 -0400 Received: by mail-ej1-f72.google.com with SMTP id a640c23a62f3a-b2ef8e0133fso114461666b.0 for ; Tue, 23 Sep 2025 03:41:43 -0700 (PDT) Received: from [192.168.10.48] ([176.206.127.188]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b293fa07816sm705154266b.50.2025.09.23.03.41.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Sep 2025 03:41:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758624105; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=S7AvEaNloXl7AAmAS1Y5CI+jWkOoqizDLL87K4Tp+NY=; b=Pu2AhFm7gI3jKQqYTlgVv49Qw7ZNqSyhYWbXPeejgPXnUZrzh/HlgvPzM6CzvZCWDfYliR kDcNgXC4DSFieAkLZ5YI6r5fPxN1T5eI9Jd13eRAW+BfwMKoqPUqpIrDM2TnFv0gz2541E fmm6pNccG62PcvOgzcaSe7JNYJPLEcg= X-MC-Unique: 53sgG4HMOW2R-9bmYnjv3Q-1 X-Mimecast-MFC-AGG-ID: 53sgG4HMOW2R-9bmYnjv3Q_1758624103 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758624102; x=1759228902; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=S7AvEaNloXl7AAmAS1Y5CI+jWkOoqizDLL87K4Tp+NY=; b=o6dsJtX0zS/4jvVug6uyUNOi9jTvLvArqxrrSERZdHPd+dJ+hQPZSeu3BfQkU1peL5 RoBVZxGUrTQRej+GTyx0CT78i7XYoL7wk1t3LNSF5Iv2fO1rjSN8BkxDz8QUEkQGNL5a ajPNi82396doEGO30q1mM8ISGRUow2qEDSeW4CW3TiRN8hOHSJEVrC+vR/BRveRfvPgt getkTVjB6vcr8Xxj6X/NSpI6HupjJmpScXdo5dpRZ7/h4nV9iCAVW7jU9q4IaAPdWQgE JZKqj2LD+6gKYpYoomKi/pMGpELGJNWY7AcD7GJr+QRbjQTIHiBwpMx9rLS+/ByN54Tv tiZA== X-Gm-Message-State: AOJu0YwxMDc/xpNbninEL3rgZCcrgJBCGZugvNTzo+qyZj0gQuYjgUWz cwPSO7LZVkMOusb7qLLpO9Bljh9+zYI3UU3MmyKzGWjbKdggSBQPE1CMw9FHHzr5qBxfxdYFLAV a3G4bi48+rzhTvAnSg5QJjwGsL1KJhmEChO/HG6hE/p4H4JGwkipBwgnBvorT7/5MQzROsmFrSb 94sH5jgn43p6u8y4zmVMwsLfwn6gZp/EsRfCSSTr/P X-Gm-Gg: ASbGncu6jQITfGX2MFyRkDSYuPUQQuYpjgk5x2Jdj4GCR8jI9/v52XQoiuWYO0++zJJ glafcGmubhm/6+QVS8mIb+GsFuu/kvY6Pa5n6n8ZEtC/H2JFpVVD3CbDsnO9KO3aA8QB3TjZ69g LgC0yOz6qxpg6cCXpUn65SLypD0eCGO0fCgi59WywPGVcRMSVkzEgqXTUMaQlOhBJ32EfLT9/GU nxgHeH+iTfNajm6MTGxF7QXfZQUJ3h4WZy/bn3VPE8k7K+3qWGlVDastwL5g9ekQhaUzMAhK9h+ h3rEGiJ4aP/kTPmBJXxFlp6GQ6HG9AaUNqYBTW5Hdh7fydw6SJiqaCZsTzGcBnEsa2A8VyqjLYg MfbmfLuu6dmQ1u9OCXyg5SK8PivpOhTQs6uI4Fz5kjAt6Vg== X-Received: by 2002:a17:907:1c27:b0:b0c:8280:4f40 with SMTP id a640c23a62f3a-b30263b326cmr185971366b.4.1758624101780; Tue, 23 Sep 2025 03:41:41 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEQHA7tA9o69d7U0g0p3zAVDXr1/8g6AOZ2G8tUZEkq3lbwxBT9w7wKwDklgOoCyuqiIRJtEw== X-Received: by 2002:a17:907:1c27:b0:b0c:8280:4f40 with SMTP id a640c23a62f3a-b30263b326cmr185966466b.4.1758624101222; Tue, 23 Sep 2025 03:41:41 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: hector.cao@canonical.com, lk@c--e.de, berrange@redhat.com Subject: [RFT PATCH v2 1/2] target/i386: add compatibility property for arch_capabilities Date: Tue, 23 Sep 2025 12:41:35 +0200 Message-ID: <20250923104136.133875-2-pbonzini@redhat.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250923104136.133875-1-pbonzini@redhat.com> References: <20250923104136.133875-1-pbonzini@redhat.com> 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=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.442, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1758624135978116600 Content-Type: text/plain; charset="utf-8" Prior to v10.1, if requested by user, arch-capabilities is always on despite the fact that CPUID advertises it to be off/unvailable. This causes a migration issue for VMs that are run on a machine without arch-capabilities and expect this feature to be present on the destination host with QEMU 10.1. Add a compatibility property to restore the legacy behavior for all machines with version prior to 10.1. Co-authored-by: Hector Cao Signed-off-by: Hector Cao Fixes: d3a24134e37 ("target/i386: do not expose ARCH_CAPABILITIES on AMD CP= U", 2025-07-17) Signed-off-by: Paolo Bonzini Reviewed-by: Zhao Liu --- target/i386/cpu.h | 6 ++++++ hw/i386/pc.c | 1 + target/i386/cpu.c | 17 +++++++++++++++++ target/i386/kvm/kvm.c | 6 +----- 4 files changed, 25 insertions(+), 5 deletions(-) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index e0be7a74068..414ca968e84 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -2314,6 +2314,12 @@ struct ArchCPU { /* Forcefully disable KVM PV features not exposed in guest CPUIDs */ bool kvm_pv_enforce_cpuid; =20 + /* + * Expose arch-capabilities unconditionally even on AMD models, for ba= ckwards + * compatibility with QEMU <10.1. + */ + bool arch_cap_always_on; + /* Number of physical address bits supported */ uint32_t phys_bits; =20 diff --git a/hw/i386/pc.c b/hw/i386/pc.c index bc048a6d137..d7f48150fdd 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -87,6 +87,7 @@ const size_t pc_compat_10_1_len =3D G_N_ELEMENTS(pc_compa= t_10_1); GlobalProperty pc_compat_10_0[] =3D { { TYPE_X86_CPU, "x-consistent-cache", "false" }, { TYPE_X86_CPU, "x-vendor-cpuid-only-v2", "false" }, + { TYPE_X86_CPU, "x-arch-cap-always-on", "true" }, }; const size_t pc_compat_10_0_len =3D G_N_ELEMENTS(pc_compat_10_0); =20 diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 6d85149e6e1..fe369bb1284 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -7539,6 +7539,20 @@ uint64_t x86_cpu_get_supported_feature_word(X86CPU *= cpu, FeatureWord w) #endif break; =20 + case FEAT_7_0_EDX: + /* + * Windows does not like ARCH_CAPABILITIES on AMD machines at all. + * Do not show the fake ARCH_CAPABILITIES MSR that KVM sets up, + * except if needed for migration. + * + * When arch_cap_always_on is removed, this tweak can move to + * kvm_arch_get_supported_cpuid. + */ + if (cpu && IS_AMD_CPU(&cpu->env) && !cpu->arch_cap_always_on) { + unavail =3D CPUID_7_0_EDX_ARCH_CAPABILITIES; + } + break; + default: break; } @@ -10004,6 +10018,9 @@ static const Property x86_cpu_properties[] =3D { true), DEFINE_PROP_BOOL("x-l1-cache-per-thread", X86CPU, l1_cache_per_core, t= rue), DEFINE_PROP_BOOL("x-force-cpuid-0x1f", X86CPU, force_cpuid_0x1f, false= ), + + DEFINE_PROP_BOOL("x-arch-cap-always-on", X86CPU, + arch_cap_always_on, false), }; =20 #ifndef CONFIG_USER_ONLY diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 6a3a1c1ed8e..db40caa3412 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -503,12 +503,8 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uin= t32_t function, * Linux v4.17-v4.20 incorrectly return ARCH_CAPABILITIES on SVM h= osts. * We can detect the bug by checking if MSR_IA32_ARCH_CAPABILITIES= is * returned by KVM_GET_MSR_INDEX_LIST. - * - * But also, because Windows does not like ARCH_CAPABILITIES on AMD - * mcahines at all, do not show the fake ARCH_CAPABILITIES MSR that - * KVM sets up. */ - if (!has_msr_arch_capabs || !(edx & CPUID_7_0_EDX_ARCH_CAPABILITIE= S)) { + if (!has_msr_arch_capabs) { ret &=3D ~CPUID_7_0_EDX_ARCH_CAPABILITIES; } } else if (function =3D=3D 7 && index =3D=3D 1 && reg =3D=3D R_EAX) { --=20 2.51.0 From nobody Sun Sep 28 15:30:17 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; 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; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1758624151; cv=none; d=zohomail.com; s=zohoarc; b=PLT10LtpSDggKYLPj81ilZddG9PygDSDXKQ3Tknqe08hcZH8A7yo0m0729yw0BI75Aagg1v6dsojf/UIZz1gADaf0fjT6HUXV5vLWclHZfi5fOe4zaWA5YxLEIuXPJvBmKeWKOBjF5hhbDPpL/2KmTmljy5W/WXyucijwMzyBzA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1758624151; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=a375QZbeNwmaWpIoRvdNLtIS+2HVCnHIvRjrNsLKivI=; b=hF0fGmxkan7A1AepRXr05iDx1yMpDBi7Yvxcqmrjof3g/wwmuvOF/381upDx6wRFexvJeKx6Oeq7qq9RaKzoKoZOJr2G8+3bTCYyQ1NndNA4GaSOHpjOQlPNbJEy7TMzaNgcOdfMdVma3UXT34uNTCYiggNxd5WN6XvBRCQfFX4= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; 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; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1758624151450595.8012893934268; Tue, 23 Sep 2025 03:42:31 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v10T7-0004iz-So; Tue, 23 Sep 2025 06:41:58 -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 1v10T6-0004hv-7D for qemu-devel@nongnu.org; Tue, 23 Sep 2025 06:41:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v10T0-0006DH-Sm for qemu-devel@nongnu.org; Tue, 23 Sep 2025 06:41:55 -0400 Received: from mail-ej1-f70.google.com (mail-ej1-f70.google.com [209.85.218.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-191-2ffC2dplPtinRShS1E7X2g-1; Tue, 23 Sep 2025 06:41:46 -0400 Received: by mail-ej1-f70.google.com with SMTP id a640c23a62f3a-b2ee3c13b3eso91697166b.2 for ; Tue, 23 Sep 2025 03:41:45 -0700 (PDT) Received: from [192.168.10.48] ([176.206.127.188]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-62fa5f287d9sm10683105a12.44.2025.09.23.03.41.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Sep 2025 03:41:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758624107; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=a375QZbeNwmaWpIoRvdNLtIS+2HVCnHIvRjrNsLKivI=; b=cCIzNFDwN9ylseh4a4A5aDha7yogbsz/+S++GV2wzUgeLv2r2SRUg0OGqyeBhn0exd0Op1 S7pqJSUN9XpVbh1dwChDhuy3sV7hqYLmTWeu5MzaUbdAaMIRYwuJ8sBjN7daINKHoJa5W8 DOOUW3biH/6zRO1BsUS6yZsI5PgewmE= X-MC-Unique: 2ffC2dplPtinRShS1E7X2g-1 X-Mimecast-MFC-AGG-ID: 2ffC2dplPtinRShS1E7X2g_1758624105 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758624104; x=1759228904; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=a375QZbeNwmaWpIoRvdNLtIS+2HVCnHIvRjrNsLKivI=; b=ZJ52fnvYLxtNgHyouY3CpSokyELZCH7l7V79/oTtrkpHF/t0laspCWertPbgQmSCSs qHojtNvVVxTdh73mh56ciotp+Lmrmpwhw+Zs4E3vDssRltcQL25rga/DKsr3/lIhtB8f GxIse5FVeYfr9Uq4/UIJIVbSVXPls8Su5utu2Lg3gI5OF2g8CTwGZkGUeD/txfSMwHl4 nzLBn3/N0sJayAmMbQNunWLenirZ1Y2d7xuRrnul3BJriqOzggb57KH3lQaan7qWsnNU yP5eM1zRdAhlN3qTOUrQmSP58FfUb/y0wzNUQ+fuYsvh+dN00Gg8PsoNHfS1FaJYfcPA 2ALA== X-Gm-Message-State: AOJu0YysiCgCnI20XH0bVnvTxYsSPibWVrWwc5HcSb8hqQHhRs4Vo0Eg AaEVmChnr6zj+wFMRstDYB3Eecme2cfJXmCgR6J/AMN+LsuuvcgyNaip90ZKj/lrIe6YQaBFADc Q02OYys/UrJVfF9iU1CPVB3RXV1gcOm1Q0cKM6v9SWjTpHs3G0SOSNMuJg2K7Tm8pyvUZWjcgsp Kv6tJow94FaqnjBNDbuJd6O8GLnIwxNQhGhWrrhdEv X-Gm-Gg: ASbGncu179YEXMnTtujy0W+y0gjxuBNsOiINM6JWp+ZTgB226UJONqmyHOq+jUfjrg+ fA1vAXqThv31y99Q9wQD7uohwCX/jxCxTGfgbN7qQny/j74oTAYgim02h13ju7zWqbXjLVCx2FG ipw4MKBjFehGdwRWqHu49H7btOrEKxXnwlHcIjR/CFyv33fKH0akp+Xwwr7467mmAdo3BQ+d50X fS1R9AihofS8JARe7TllEvXYwZ3g1jWiqXqLHYvnSjHl/BKj3jjqLTVU/VS7o7jDZeUjrfw4E6k dtS3m9yTmgaN7pl+f5Znsk4wqYDnOX+QR45D3TnmeDnhmWKSfuthWOFk//8OtXPlbVfi0ACD4yx jlpr6nlRfSVUBpsP9cdfrYj2GgKKqCq0L0ts+kbBQQNo5qw== X-Received: by 2002:a17:907:7f13:b0:b07:88aa:255b with SMTP id a640c23a62f3a-b302689510bmr198565766b.11.1758624103997; Tue, 23 Sep 2025 03:41:43 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEaRQct4v6u6fwKFvJ5qxUMkG5X5B2BjOJRWuJk4kwB2ravZy8/qumoVfFXg4yw/aekmyIc+g== X-Received: by 2002:a17:907:7f13:b0:b07:88aa:255b with SMTP id a640c23a62f3a-b302689510bmr198563366b.11.1758624103507; Tue, 23 Sep 2025 03:41:43 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: hector.cao@canonical.com, lk@c--e.de, berrange@redhat.com Subject: [RFT PATCH v2 2/2] target/i386: add compatibility property for pdcm feature Date: Tue, 23 Sep 2025 12:41:36 +0200 Message-ID: <20250923104136.133875-3-pbonzini@redhat.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250923104136.133875-1-pbonzini@redhat.com> References: <20250923104136.133875-1-pbonzini@redhat.com> 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=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.442, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1758624154073116600 Content-Type: text/plain; charset="utf-8" From: Hector Cao The pdcm feature is supposed to be disabled when PMU is not available. Up until v10.1, pdcm feature is enabled even when PMU is off. This behavior has been fixed but this change breaks the migration of VMs that are run with QEMU < 10.0 and expect the pdcm feature to be enabled on the destination host. This commit restores the legacy behavior for machines with version prior to 10.1 to allow the migration from older QEMU to QEMU 10.1. Signed-off-by: Hector Cao Link: https://lore.kernel.org/r/20250910115733.21149-3-hector.cao@canonical= .com Fixes: e68ec298090 ("i386/cpu: Move adjustment of CPUID_EXT_PDCM before fea= ture_dependencies[] check", 2025-06-20) [Move property from migration object to CPU. - Paolo] Signed-off-by: Paolo Bonzini Reviewed-by: Zhao Liu --- target/i386/cpu.h | 6 ++++++ hw/i386/pc.c | 1 + target/i386/cpu.c | 15 ++++++++++++--- 3 files changed, 19 insertions(+), 3 deletions(-) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 414ca968e84..42168f1d6d8 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -2320,6 +2320,12 @@ struct ArchCPU { */ bool arch_cap_always_on; =20 + /* + * Backwards compatibility with QEMU <10.1. The PDCM feature is now di= sabled when + * PMU is not available, but prior to 10.1 it was enabled even if PMU = is off. + */ + bool pdcm_on_even_without_pmu; + /* Number of physical address bits supported */ uint32_t phys_bits; =20 diff --git a/hw/i386/pc.c b/hw/i386/pc.c index d7f48150fdd..4668918746e 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -88,6 +88,7 @@ GlobalProperty pc_compat_10_0[] =3D { { TYPE_X86_CPU, "x-consistent-cache", "false" }, { TYPE_X86_CPU, "x-vendor-cpuid-only-v2", "false" }, { TYPE_X86_CPU, "x-arch-cap-always-on", "true" }, + { TYPE_X86_CPU, "x-pdcm-on-even-without-pmu", "true" }, }; const size_t pc_compat_10_0_len =3D G_N_ELEMENTS(pc_compat_10_0); =20 diff --git a/target/i386/cpu.c b/target/i386/cpu.c index fe369bb1284..ab18de894e4 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -7908,6 +7908,11 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,= uint32_t count, /* Fixup overflow: max value for bits 23-16 is 255. */ *ebx |=3D MIN(num, 255) << 16; } + if (cpu->pdcm_on_even_without_pmu) { + if (!cpu->enable_pmu) { + *ecx &=3D ~CPUID_EXT_PDCM; + } + } break; case 2: { /* cache info: needed for Pentium Pro compatibility */ const CPUCaches *caches; @@ -8958,9 +8963,11 @@ void x86_cpu_expand_features(X86CPU *cpu, Error **er= rp) } } =20 - /* PDCM is fixed1 bit for TDX */ - if (!cpu->enable_pmu && !is_tdx_vm()) { - env->features[FEAT_1_ECX] &=3D ~CPUID_EXT_PDCM; + if (!cpu->pdcm_on_even_without_pmu) { + /* PDCM is fixed1 bit for TDX */ + if (!cpu->enable_pmu && !is_tdx_vm()) { + env->features[FEAT_1_ECX] &=3D ~CPUID_EXT_PDCM; + } } =20 for (i =3D 0; i < ARRAY_SIZE(feature_dependencies); i++) { @@ -10021,6 +10028,8 @@ static const Property x86_cpu_properties[] =3D { =20 DEFINE_PROP_BOOL("x-arch-cap-always-on", X86CPU, arch_cap_always_on, false), + DEFINE_PROP_BOOL("x-pdcm-on-even-without-pmu", X86CPU, + pdcm_on_even_without_pmu, false), }; =20 #ifndef CONFIG_USER_ONLY --=20 2.51.0