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 65216C433F5 for ; Thu, 13 Jan 2022 07:42:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232375AbiAMHmj (ORCPT ); Thu, 13 Jan 2022 02:42:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:56601 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232273AbiAMHmi (ORCPT ); Thu, 13 Jan 2022 02:42:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642059757; h=from:from:reply-to: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=ue1d/msd5vIMJ1AqIu2LNoBMek//LGkHnqyUgH09KUQ=; b=JRXNO2tX9VLrb345kSVdv/Qm/SaKHgttigzFN5rgwqSfyZhLa9LdAvzU5cH1sd49MxKyqX fSyQIQPtCcoJOkI1LOWwKlDuHWG5ZFcA9FCdEBnmaqbMieYmc8v++jY2H7x9qCv8HNLUVL cbCetkGIi7ErCMPjHQF3SpiVhAgCa1w= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-343-4QNDXphRPzy9ZrcT1PZEhw-1; Thu, 13 Jan 2022 02:42:33 -0500 X-MC-Unique: 4QNDXphRPzy9ZrcT1PZEhw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 70C4C193F560; Thu, 13 Jan 2022 07:42:32 +0000 (UTC) Received: from [10.72.13.202] (ovpn-13-202.pek2.redhat.com [10.72.13.202]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 727AB5F917; Thu, 13 Jan 2022 07:42:23 +0000 (UTC) Reply-To: Gavin Shan Subject: Re: [PATCH v4 03/15] KVM: async_pf: Make GFN slot management generic To: Eric Auger , kvmarm@lists.cs.columbia.edu Cc: kvm@vger.kernel.org, maz@kernel.org, linux-kernel@vger.kernel.org, shan.gavin@gmail.com, Jonathan.Cameron@huawei.com, pbonzini@redhat.com, vkuznets@redhat.com, will@kernel.org References: <20210815005947.83699-1-gshan@redhat.com> <20210815005947.83699-4-gshan@redhat.com> <06cb06c0-13e7-906b-9b88-543a58bb5590@redhat.com> From: Gavin Shan Message-ID: <8bc39e08-abb9-91ba-3862-d5b2ccb0b7f5@redhat.com> Date: Thu, 13 Jan 2022 15:42:19 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <06cb06c0-13e7-906b-9b88-543a58bb5590@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Eric, On 11/11/21 1:00 AM, Eric Auger wrote: > On 8/15/21 2:59 AM, Gavin Shan wrote: >> It's not allowed to fire duplicate notification for same GFN on >> x86 platform, with help of a hash table. This mechanism is going > s/, with help of a hash table/this is achieved through a hash table >> to be used by arm64 and this makes the code generic and shareable > s/and this makes/.\n Turn the code generic >> by multiple platforms. >> >> * As this mechanism isn't needed by all platforms, a new kernel >> config option (CONFIG_ASYNC_PF_SLOT) is introduced so that it >> can be disabled at compiling time. > compile time Ok. >> >> * The code is basically copied from x86 platform and the functions >> are renamed to reflect the fact: (a) the input parameters are >> vCPU and GFN. > not for reset > (b) The operations are resetting, searching, adding Ok. >> and removing. > find, add, remove ops are renamed with _slot suffix Ok. The commit log will be improved based on your suggestions in next respin :) >> >> * Helper stub is also added on !CONFIG_KVM_ASYNC_PF because we're >> going to use IS_ENABLED() instead of #ifdef on arm64 when the >> asynchronous page fault is supported. >> >> This is preparatory work to use the newly introduced functions on x86 >> platform and arm64 in subsequent patches. >> >> Signed-off-by: Gavin Shan >> --- >> include/linux/kvm_host.h | 18 +++++++++ >> virt/kvm/Kconfig | 3 ++ >> virt/kvm/async_pf.c | 85 ++++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 106 insertions(+) >> >> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h >> index a5f990f6dc35..a9685c2b2250 100644 >> --- a/include/linux/kvm_host.h >> +++ b/include/linux/kvm_host.h >> @@ -298,6 +298,9 @@ struct kvm_vcpu { >> >> #ifdef CONFIG_KVM_ASYNC_PF >> struct { >> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT >> + gfn_t gfns[ASYNC_PF_PER_VCPU]; >> +#endif >> u32 queued; >> struct list_head queue; >> struct list_head done; >> @@ -339,6 +342,13 @@ struct kvm_async_pf { >> bool notpresent_injected; >> }; >> >> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT >> +void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu); > this does not reset a "slot" but the whole hash table. So to me this > shouldn't be renamed with _slot suffix. reset_hash or reset_all_slots? Sure, lets have kvm_async_pf_reset_all_slots() in next respin. >> +void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn); >> +void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn); >> +bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn); >> +#endif >> + >> static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu) >> { >> return !list_empty_careful(&vcpu->async_pf.done); >> @@ -350,6 +360,14 @@ bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, >> unsigned long hva, struct kvm_arch_async_pf *arch); >> int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu); >> #else >> +static inline void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu) { } >> +static inline void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn) { } >> +static inline void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn) { } >> +static inline bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn) >> +{ >> + return false; >> +} >> + >> static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu) >> { >> return false; >> diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig >> index 62b39149b8c8..59b518c8c205 100644 >> --- a/virt/kvm/Kconfig >> +++ b/virt/kvm/Kconfig >> @@ -23,6 +23,9 @@ config KVM_MMIO >> config KVM_ASYNC_PF >> bool >> >> +config KVM_ASYNC_PF_SLOT >> + bool >> + >> # Toggle to switch between direct notification and batch job >> config KVM_ASYNC_PF_SYNC >> bool >> diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c >> index d145a61a046a..0d1fdb2932af 100644 >> --- a/virt/kvm/async_pf.c >> +++ b/virt/kvm/async_pf.c >> @@ -13,12 +13,97 @@ >> #include >> #include >> #include >> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT >> +#include >> +#endif >> >> #include "async_pf.h" >> #include >> >> static struct kmem_cache *async_pf_cache; >> >> +#ifdef CONFIG_KVM_ASYNC_PF_SLOT >> +static inline u32 kvm_async_pf_hash(gfn_t gfn) >> +{ >> + BUILD_BUG_ON(!is_power_of_2(ASYNC_PF_PER_VCPU)); >> + >> + return hash_32(gfn & 0xffffffff, order_base_2(ASYNC_PF_PER_VCPU)); >> +} >> + >> +static inline u32 kvm_async_pf_next_slot(u32 key) >> +{ >> + return (key + 1) & (ASYNC_PF_PER_VCPU - 1); >> +} >> + >> +static u32 kvm_async_pf_slot(struct kvm_vcpu *vcpu, gfn_t gfn) >> +{ >> + u32 key = kvm_async_pf_hash(gfn); >> + int i; >> + >> + for (i = 0; i < ASYNC_PF_PER_VCPU && >> + (vcpu->async_pf.gfns[key] != gfn && >> + vcpu->async_pf.gfns[key] != ~0); i++) >> + key = kvm_async_pf_next_slot(key); >> + >> + return key; >> +} >> + >> +void kvm_async_pf_reset_slot(struct kvm_vcpu *vcpu) >> +{ >> + int i; >> + >> + for (i = 0; i < ASYNC_PF_PER_VCPU; i++) >> + vcpu->async_pf.gfns[i] = ~0; >> +} >> + >> +void kvm_async_pf_add_slot(struct kvm_vcpu *vcpu, gfn_t gfn) >> +{ >> + u32 key = kvm_async_pf_hash(gfn); >> + >> + while (vcpu->async_pf.gfns[key] != ~0) >> + key = kvm_async_pf_next_slot(key); >> + >> + vcpu->async_pf.gfns[key] = gfn; >> +} >> + >> +void kvm_async_pf_remove_slot(struct kvm_vcpu *vcpu, gfn_t gfn) >> +{ >> + u32 i, j, k; >> + >> + i = j = kvm_async_pf_slot(vcpu, gfn); >> + >> + if (WARN_ON_ONCE(vcpu->async_pf.gfns[i] != gfn)) >> + return; >> + >> + while (true) { >> + vcpu->async_pf.gfns[i] = ~0; >> + >> + do { >> + j = kvm_async_pf_next_slot(j); >> + if (vcpu->async_pf.gfns[j] == ~0) >> + return; >> + >> + k = kvm_async_pf_hash(vcpu->async_pf.gfns[j]); >> + /* >> + * k lies cyclically in ]i,j] >> + * | i.k.j | >> + * |....j i.k.| or |.k..j i...| >> + */ >> + } while ((i <= j) ? (i < k && k <= j) : (i < k || k <= j)); >> + >> + vcpu->async_pf.gfns[i] = vcpu->async_pf.gfns[j]; >> + i = j; >> + } >> +} >> + >> +bool kvm_async_pf_find_slot(struct kvm_vcpu *vcpu, gfn_t gfn) >> +{ >> + u32 key = kvm_async_pf_slot(vcpu, gfn); >> + >> + return vcpu->async_pf.gfns[key] == gfn; >> +} >> +#endif /* CONFIG_KVM_ASYNC_PF_SLOT */ >> + >> int kvm_async_pf_init(void) >> { >> async_pf_cache = KMEM_CACHE(kvm_async_pf, 0); >> Thanks, Gavin