From nobody Thu Apr 2 21:30:43 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C1F8C54EE9 for ; Tue, 20 Sep 2022 23:33:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231483AbiITXdB (ORCPT ); Tue, 20 Sep 2022 19:33:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45200 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231263AbiITXcJ (ORCPT ); Tue, 20 Sep 2022 19:32:09 -0400 Received: from mail-pg1-x54a.google.com (mail-pg1-x54a.google.com [IPv6:2607:f8b0:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 59C0B72EC7 for ; Tue, 20 Sep 2022 16:32:04 -0700 (PDT) Received: by mail-pg1-x54a.google.com with SMTP id 126-20020a630284000000b0043942ef3ac7so2469467pgc.11 for ; Tue, 20 Sep 2022 16:32:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date; bh=0DnOm1NQnF4hm1qkEkLlMwUTgosZ5jnSBllcwGj9ntA=; b=ceL8V6iuTN2If+GjMd7E4cw5E3mU5rOZz58FfjwrGzQ5uNfCW135h1xlxXDN8dhwMw 2N1/IEnM0z42IbDG8uclYaGuse0ixWQJzpEcqLmf/SgTuUxIdgQK3r9CFZ08u/cwR+e+ j1TLdKsQcP0CcuGLd+R3t5SjBPGmtwU3BbopZwFYdqi2bWqEppPfQxohMH4LC+05iMTJ +TDlgHTJ+yKK0vI182Nm1403BHgQUExJqbmurUwiLxMKLaXPJJ+oCt3SpxTvmXAlUxna WWHlPZp9d48JTyFJ0fFhBg1ahja0msQkz13pl2PDA2v43auqgsI3UvnnUJ4xi34js6KL 5zLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date; bh=0DnOm1NQnF4hm1qkEkLlMwUTgosZ5jnSBllcwGj9ntA=; b=m/0s9+Bj+BxXLfzqLH8yJjWwp5rbvIjc64CCwCkBYcRTbNgsvi4k6OW0b2+dyqXU4B Punp6QCH5LJF/nxMoTYyJBg4rVCTslLmsSdeLMq10BmDaCekdttdaBVmwtxLx+LZfC9M vpi+8l5uLThWwfzQqYeWVZO7ksYO5J386eVsZwrTZHN/oWxCAUelpO7XI0+bT4mAkOkh fIB8IDWeH0J3ihNR5y+RRifITIxYD+yHLvwNQu47ouzdm7smko0MA5mojPjiR2Jv4WhQ yJu2bsvOAUfYBlrpHOqRXdu+vL4r/ToxRKPvSGbyzrZDmPWwwdaybJrqU42OD0twh9Yi D6wg== X-Gm-Message-State: ACrzQf28+Zk+Ku9pVwssmpJlnKE5FGCzgDYrvQjtJFz3JdrGM5DperqO naSJUHG0A7scvsAtl/aY/V70tlzR/Y8= X-Google-Smtp-Source: AMsMyM4GS77Mx8WQq+RtjB/Ved5Et/xk/5SK5HeCEKuFxFf4ftlw3ChZyu3Kwk0MDW3j1vVGUf9Oln6+ygQ= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6a00:1d82:b0:541:1ea2:e7e with SMTP id z2-20020a056a001d8200b005411ea20e7emr26811472pfw.71.1663716723791; Tue, 20 Sep 2022 16:32:03 -0700 (PDT) Reply-To: Sean Christopherson Date: Tue, 20 Sep 2022 23:31:22 +0000 In-Reply-To: <20220920233134.940511-1-seanjc@google.com> Mime-Version: 1.0 References: <20220920233134.940511-1-seanjc@google.com> X-Mailer: git-send-email 2.37.3.968.ga6b4b080e4-goog Message-ID: <20220920233134.940511-17-seanjc@google.com> Subject: [PATCH v3 16/28] KVM: x86: Explicitly track all possibilities for APIC map's logical modes From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Alejandro Jimenez , Suravee Suthikulpanit , Maxim Levitsky , Li RongQing Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Track all possibilities for the optimized APIC map's logical modes instead of overloading the pseudo-bitmap and treating any "unknown" value as "invalid". As documented by the now-stale comment above the mode values, the values did have meaning when the optimized map was originally added. That dependent logical was removed by commit e45115b62f9a ("KVM: x86: use physical LAPIC array for logical x2APIC"), but the obfuscated behavior and its comment were left behind. Opportunistically rename "mode" to "logical_mode", partly to make it clear that the "disabled" case applies only to the logical map, but also to prove that there is no lurking code that expects "mode" to be a bitmap. Functionally, this is a glorified nop. Signed-off-by: Sean Christopherson --- arch/x86/include/asm/kvm_host.h | 21 +++++++++++--------- arch/x86/kvm/lapic.c | 35 +++++++++++++++++++++++++-------- 2 files changed, 39 insertions(+), 17 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_hos= t.h index 6475c882b359..6570b5d728ef 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -955,19 +955,22 @@ struct kvm_arch_memory_slot { }; =20 /* - * We use as the mode the number of bits allocated in the LDR for the - * logical processor ID. It happens that these are all powers of two. - * This makes it is very easy to detect cases where the APICs are - * configured for multiple modes; in that case, we cannot use the map and - * hence cannot use kvm_irq_delivery_to_apic_fast either. + * Track the mode of the optimized logical map, as the rules for decoding = the + * destination vary per mode. Enabling the optimized logical map requires= all + * software-enabled local APIs to be in the same mode, each addressable AP= IC to + * be mapped to only one MDA, and each MDA to map to at most one APIC. */ -#define KVM_APIC_MODE_XAPIC_CLUSTER 4 -#define KVM_APIC_MODE_XAPIC_FLAT 8 -#define KVM_APIC_MODE_X2APIC 16 +enum kvm_apic_logical_mode { + KVM_APIC_MODE_SW_DISABLED, + KVM_APIC_MODE_XAPIC_CLUSTER, + KVM_APIC_MODE_XAPIC_FLAT, + KVM_APIC_MODE_X2APIC, + KVM_APIC_MODE_MAP_DISABLED, +}; =20 struct kvm_apic_map { struct rcu_head rcu; - u8 mode; + enum kvm_apic_logical_mode logical_mode; u32 max_apic_id; union { struct kvm_lapic *xapic_flat_map[8]; diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index bf647af50031..84b7a1c1834d 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -168,7 +168,12 @@ static bool kvm_use_posted_timer_interrupt(struct kvm_= vcpu *vcpu) =20 static inline bool kvm_apic_map_get_logical_dest(struct kvm_apic_map *map, u32 dest_id, struct kvm_lapic ***cluster, u16 *mask) { - switch (map->mode) { + switch (map->logical_mode) { + case KVM_APIC_MODE_SW_DISABLED: + /* Arbitrarily use the flat map so that @cluster isn't NULL. */ + *cluster =3D map->xapic_flat_map; + *mask =3D 0; + return true; case KVM_APIC_MODE_X2APIC: { u32 offset =3D (dest_id >> 16) * 16; u32 max_apic_id =3D map->max_apic_id; @@ -193,8 +198,10 @@ static inline bool kvm_apic_map_get_logical_dest(struc= t kvm_apic_map *map, *cluster =3D map->xapic_cluster_map[(dest_id >> 4) & 0xf]; *mask =3D dest_id & 0xf; return true; + case KVM_APIC_MODE_MAP_DISABLED: + return false; default: - /* Not optimized. */ + WARN_ON_ONCE(1); return false; } } @@ -256,10 +263,12 @@ void kvm_recalculate_apic_map(struct kvm *kvm) goto out; =20 new->max_apic_id =3D max_id; + new->logical_mode =3D KVM_APIC_MODE_SW_DISABLED; =20 kvm_for_each_vcpu(i, vcpu, kvm) { struct kvm_lapic *apic =3D vcpu->arch.apic; struct kvm_lapic **cluster; + enum kvm_apic_logical_mode logical_mode; u16 mask; u32 ldr; u8 xapic_id; @@ -282,7 +291,8 @@ void kvm_recalculate_apic_map(struct kvm *kvm) if (!apic_x2apic_mode(apic) && !new->phys_map[xapic_id]) new->phys_map[xapic_id] =3D apic; =20 - if (!kvm_apic_sw_enabled(apic)) + if (new->logical_mode =3D=3D KVM_APIC_MODE_MAP_DISABLED || + !kvm_apic_sw_enabled(apic)) continue; =20 ldr =3D kvm_lapic_get_reg(apic, APIC_LDR); @@ -290,17 +300,26 @@ void kvm_recalculate_apic_map(struct kvm *kvm) continue; =20 if (apic_x2apic_mode(apic)) { - new->mode |=3D KVM_APIC_MODE_X2APIC; + logical_mode =3D KVM_APIC_MODE_X2APIC; } else { ldr =3D GET_APIC_LOGICAL_ID(ldr); if (kvm_lapic_get_reg(apic, APIC_DFR) =3D=3D APIC_DFR_FLAT) - new->mode |=3D KVM_APIC_MODE_XAPIC_FLAT; + logical_mode =3D KVM_APIC_MODE_XAPIC_FLAT; else - new->mode |=3D KVM_APIC_MODE_XAPIC_CLUSTER; + logical_mode =3D KVM_APIC_MODE_XAPIC_CLUSTER; } + if (new->logical_mode !=3D KVM_APIC_MODE_SW_DISABLED && + new->logical_mode !=3D logical_mode) { + new->logical_mode =3D KVM_APIC_MODE_MAP_DISABLED; + continue; + } + new->logical_mode =3D logical_mode; =20 - if (!kvm_apic_map_get_logical_dest(new, ldr, &cluster, &mask)) + if (WARN_ON_ONCE(!kvm_apic_map_get_logical_dest(new, ldr, + &cluster, &mask))) { + new->logical_mode =3D KVM_APIC_MODE_MAP_DISABLED; continue; + } =20 if (mask) cluster[ffs(mask) - 1] =3D apic; @@ -953,7 +972,7 @@ static bool kvm_apic_is_broadcast_dest(struct kvm *kvm,= struct kvm_lapic **src, { if (kvm->arch.x2apic_broadcast_quirk_disabled) { if ((irq->dest_id =3D=3D APIC_BROADCAST && - map->mode !=3D KVM_APIC_MODE_X2APIC)) + map->logical_mode !=3D KVM_APIC_MODE_X2APIC)) return true; if (irq->dest_id =3D=3D X2APIC_BROADCAST) return true; --=20 2.37.3.968.ga6b4b080e4-goog