From mboxrd@z Thu Jan 1 00:00:00 1970 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 70F48C54EBD for ; Sun, 8 Jan 2023 15:15:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233646AbjAHPPN (ORCPT ); Sun, 8 Jan 2023 10:15:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44952 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233630AbjAHPPL (ORCPT ); Sun, 8 Jan 2023 10:15:11 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29DFFC777 for ; Sun, 8 Jan 2023 07:14:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1673190866; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KrNzL9H0g0To9mb4Yi3WrwmErBqjyBobKqupLVMbqzk=; b=KrZPtTfvFBIi9Oo2FfTT8JVKcn+QDbk2R5doWylxh0SkzbFzDptJJT+MUWbh989ZvohG// DKVM/Rm+bnyU7FlaC5f9skdAfO8L2Zapg3bePwj54rdN2zs6o5u0B76QwfZ/TZrrMTsy5c BNaUDrPYEurlHgdTtEmBvgLn6xVJQxk= Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-551-xFMIqZQHPU-fxp8wdTlXug-1; Sun, 08 Jan 2023 10:14:23 -0500 X-MC-Unique: xFMIqZQHPU-fxp8wdTlXug-1 Received: by mail-ed1-f71.google.com with SMTP id i8-20020a05640242c800b004852914ce42so3851144edc.6 for ; Sun, 08 Jan 2023 07:14:22 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:user-agent:references :in-reply-to:date:cc:to:from:subject:message-id:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=KrNzL9H0g0To9mb4Yi3WrwmErBqjyBobKqupLVMbqzk=; b=C8X3uxkBQhVCJxVJzEHHqUezWaN3m4JuRhKOHD0OJRsFhpgCpkNqBnGBzWUGeToDoO TnTO84jIgYImHX396SNSIm4K6t65qWRCHQybRDA8EbQl2cdLkMyYwmTykL3qUSzWgooK gz8tt5Mk7OcQoyUhid7Cu/Fs+a7TruBCzqe61CKDvbAFoyli15yDmUW1sMoRcJlpOxSg hhHRBPWFLTzkUBoWp+cfIOaVNiUWF8P4K+wB7IA7QzhXrJJ+M0AkCBrkcAd7b7VyPBUI Y7sUfTJ7pWtCljo/muuJuXFD7/j/Os8rA5OgdAQLRhBdfqJMACm5WDe69lZT7D+A3t0K 7K8w== X-Gm-Message-State: AFqh2koIrx4f7/3Y1SYj0pdVf0naMp3rxUW/2DzXoRxTddDTTYA5Z/ZN MxXBpAEF51kLmgf3kgSyWLJBf4uRFjn9xMgM1ZSY3+bXM+WVKnoH4E+x9oq5DVOkcyDtVBo87wx l7uL3PzCIzA8JOQkiRvg7L5kZ X-Received: by 2002:a17:907:8c81:b0:7c0:d0ba:e81f with SMTP id td1-20020a1709078c8100b007c0d0bae81fmr53863834ejc.1.1673190862026; Sun, 08 Jan 2023 07:14:22 -0800 (PST) X-Google-Smtp-Source: AMrXdXu9iaEJPvVwmfapV0HLjb73fKtadS4wUOlymKcJXMLyxWWx8abIXcqGv7iMRtlcfKokkJx3jw== X-Received: by 2002:a17:907:8c81:b0:7c0:d0ba:e81f with SMTP id td1-20020a1709078c8100b007c0d0bae81fmr53863819ejc.1.1673190861834; Sun, 08 Jan 2023 07:14:21 -0800 (PST) Received: from starship ([89.237.103.62]) by smtp.gmail.com with ESMTPSA id l10-20020a1709063d2a00b0084767d40f0dsm2587338ejf.115.2023.01.08.07.14.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Jan 2023 07:14:21 -0800 (PST) Message-ID: Subject: Re: [PATCH v5 18/33] KVM: x86: Explicitly track all possibilities for APIC map's logical modes From: Maxim Levitsky To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Alejandro Jimenez , Suravee Suthikulpanit , Li RongQing , Greg Edwards Date: Sun, 08 Jan 2023 17:14:19 +0200 In-Reply-To: <20230106011306.85230-19-seanjc@google.com> References: <20230106011306.85230-1-seanjc@google.com> <20230106011306.85230-19-seanjc@google.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2023-01-06 at 01:12 +0000, Sean Christopherson wrote: > 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 | 29 ++++++++++++++++-------- > arch/x86/kvm/lapic.c | 40 ++++++++++++++++++++++++++------- > 2 files changed, 52 insertions(+), 17 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 1d92c148e799..732421a0ad02 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1022,19 +1022,30 @@ struct kvm_arch_memory_slot { > }; > > /* > - * 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 APIC 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 { > + /* All local APICs are software disabled. */ > + KVM_APIC_MODE_SW_DISABLED, > + /* All software enabled local APICs in xAPIC cluster addressing mode. */ > + KVM_APIC_MODE_XAPIC_CLUSTER, > + /* All software enabled local APICs in xAPIC flat addressing mode. */ > + KVM_APIC_MODE_XAPIC_FLAT, > + /* All software enabled local APICs in x2APIC mode. */ > + KVM_APIC_MODE_X2APIC, > + /* > + * Optimized map disabled, e.g. not all local APICs in the same logical > + * mode, same logical ID assigned to multiple APICs, etc. > + */ > + KVM_APIC_MODE_MAP_DISABLED, > +}; > > 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 2aee712e42bb..2567998b692c 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) > > 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 = map->xapic_flat_map; > + *mask = 0; > + return true; > case KVM_APIC_MODE_X2APIC: { > u32 offset = (dest_id >> 16) * 16; > u32 max_apic_id = map->max_apic_id; > @@ -193,8 +198,10 @@ static inline bool kvm_apic_map_get_logical_dest(struct kvm_apic_map *map, > *cluster = map->xapic_cluster_map[(dest_id >> 4) & 0xf]; > *mask = 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; > > new->max_apic_id = max_id; > + new->logical_mode = KVM_APIC_MODE_SW_DISABLED; > > kvm_for_each_vcpu(i, vcpu, kvm) { > struct kvm_lapic *apic = 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] = apic; > > - if (!kvm_apic_sw_enabled(apic)) > + if (new->logical_mode == KVM_APIC_MODE_MAP_DISABLED || > + !kvm_apic_sw_enabled(apic)) > continue; > > ldr = kvm_lapic_get_reg(apic, APIC_LDR); > @@ -290,17 +300,31 @@ void kvm_recalculate_apic_map(struct kvm *kvm) > continue; > > if (apic_x2apic_mode(apic)) { > - new->mode |= KVM_APIC_MODE_X2APIC; > + logical_mode = KVM_APIC_MODE_X2APIC; > } else { > ldr = GET_APIC_LOGICAL_ID(ldr); > if (kvm_lapic_get_reg(apic, APIC_DFR) == APIC_DFR_FLAT) > - new->mode |= KVM_APIC_MODE_XAPIC_FLAT; > + logical_mode = KVM_APIC_MODE_XAPIC_FLAT; > else > - new->mode |= KVM_APIC_MODE_XAPIC_CLUSTER; > + logical_mode = KVM_APIC_MODE_XAPIC_CLUSTER; > } > > - if (!kvm_apic_map_get_logical_dest(new, ldr, &cluster, &mask)) > + /* > + * To optimize logical mode delivery, all software-enabled APICs must > + * be configured for the same mode. > + */ > + if (new->logical_mode == KVM_APIC_MODE_SW_DISABLED) { > + new->logical_mode = logical_mode; > + } else if (new->logical_mode != logical_mode) { > + new->logical_mode = KVM_APIC_MODE_MAP_DISABLED; > continue; > + } > + > + if (WARN_ON_ONCE(!kvm_apic_map_get_logical_dest(new, ldr, > + &cluster, &mask))) { > + new->logical_mode = KVM_APIC_MODE_MAP_DISABLED; > + continue; > + } > > if (mask) > cluster[ffs(mask) - 1] = apic; > @@ -953,7 +977,7 @@ 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 == APIC_BROADCAST && > - map->mode != KVM_APIC_MODE_X2APIC)) > + map->logical_mode != KVM_APIC_MODE_X2APIC)) > return true; > if (irq->dest_id == X2APIC_BROADCAST) > return true; Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky