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 2CDFCC433FE for ; Wed, 11 May 2022 11:25:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235064AbiEKLZr (ORCPT ); Wed, 11 May 2022 07:25:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55444 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233165AbiEKLZN (ORCPT ); Wed, 11 May 2022 07:25:13 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3BF8B233A60 for ; Wed, 11 May 2022 04:25:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652268312; 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=E3SMRXqsstz0EchZ3i+/47gIeV51H2D0+mjmkk2ADgA=; b=ZBM07f/wWY5zxldKgPCF5zi6JLYMz3lLAbt/Qs6HewK13Gv8029mXAaj9s51rHOPO/ZK+w xbHm2YlJv+ZewYg+V+U5WlBKxMimCtjTEMCYBwbBiHZ8FQI3fQxBp5lKGPZKkZT4HZmX+W 0lD7ObPyRUWZo8ifS/bS1hM6W2r1SMQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-141--41tuohJNmOGAg93RiY5Tg-1; Wed, 11 May 2022 07:25:08 -0400 X-MC-Unique: -41tuohJNmOGAg93RiY5Tg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 72787101AA45; Wed, 11 May 2022 11:25:07 +0000 (UTC) Received: from starship (unknown [10.40.192.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2DF4640C1244; Wed, 11 May 2022 11:25:04 +0000 (UTC) Message-ID: <529a8fcd87cebb24d58d403a8d5fc91f6a72d021.camel@redhat.com> Subject: Re: [PATCH v3 11/34] KVM: x86: hyper-v: Use preallocated buffer in 'struct kvm_vcpu_hv' instead of on-stack 'sparse_banks' From: Maxim Levitsky To: Vitaly Kuznetsov , kvm@vger.kernel.org, Paolo Bonzini Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , Michael Kelley , Siddharth Chandrasekaran , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 11 May 2022 14:25:04 +0300 In-Reply-To: <20220414132013.1588929-12-vkuznets@redhat.com> References: <20220414132013.1588929-1-vkuznets@redhat.com> <20220414132013.1588929-12-vkuznets@redhat.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 X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Thu, 2022-04-14 at 15:19 +0200, Vitaly Kuznetsov wrote: > To make kvm_hv_flush_tlb() ready to handle L2 TLB flush requests, KVM needs > to allow for all 64 sparse vCPU banks regardless of KVM_MAX_VCPUs as L1 > may use vCPU overcommit for L2. To avoid growing on-stack allocation, make > 'sparse_banks' part of per-vCPU 'struct kvm_vcpu_hv' which is allocated > dynamically. > > Note: sparse_set_to_vcpu_mask() keeps using on-stack allocation as it > won't be used to handle L2 TLB flush requests. > > Signed-off-by: Vitaly Kuznetsov > --- > arch/x86/include/asm/kvm_host.h | 3 +++ > arch/x86/kvm/hyperv.c | 6 ++++-- > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 058061621872..837c07e213de 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -619,6 +619,9 @@ struct kvm_vcpu_hv { > } cpuid_cache; > > struct kvm_vcpu_hv_tlb_flush_ring tlb_flush_ring[HV_NR_TLB_FLUSH_RINGS]; > + > + /* Preallocated buffer for handling hypercalls passing sparse vCPU set */ > + u64 sparse_banks[64]; > }; > > /* Xen HVM per vcpu emulation context */ > diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c > index 1cef2b8f7001..e9793d36acca 100644 > --- a/arch/x86/kvm/hyperv.c > +++ b/arch/x86/kvm/hyperv.c > @@ -1968,6 +1968,8 @@ void kvm_hv_vcpu_flush_tlb(struct kvm_vcpu *vcpu) > > static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) > { > + struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); > + u64 *sparse_banks = hv_vcpu->sparse_banks; > struct kvm *kvm = vcpu->kvm; > struct hv_tlb_flush_ex flush_ex; > struct hv_tlb_flush flush; > @@ -1982,7 +1984,6 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) > u64 __tlb_flush_entries[KVM_HV_TLB_FLUSH_RING_SIZE - 2]; > u64 *tlb_flush_entries; > u64 valid_bank_mask; > - u64 sparse_banks[KVM_HV_MAX_SPARSE_VCPU_SET_BITS]; > struct kvm_vcpu *v; > unsigned long i; > bool all_cpus; > @@ -2134,11 +2135,12 @@ static void kvm_hv_send_ipi_to_many(struct kvm *kvm, u32 vector, > > static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) > { > + struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); > + u64 *sparse_banks = hv_vcpu->sparse_banks; > struct kvm *kvm = vcpu->kvm; > struct hv_send_ipi_ex send_ipi_ex; > struct hv_send_ipi send_ipi; > unsigned long valid_bank_mask; > - u64 sparse_banks[KVM_HV_MAX_SPARSE_VCPU_SET_BITS]; > u32 vector; > bool all_cpus; > Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky