From patchwork Mon Dec 6 19:54:33 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej S. Szmigiero" X-Patchwork-Id: 12659649 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 5E1CDC433EF for ; Mon, 6 Dec 2021 19:57:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349349AbhLFUBQ (ORCPT ); Mon, 6 Dec 2021 15:01:16 -0500 Received: from vps-vb.mhejs.net ([37.28.154.113]:50620 "EHLO vps-vb.mhejs.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349472AbhLFUA4 (ORCPT ); Mon, 6 Dec 2021 15:00:56 -0500 Received: from MUA by vps-vb.mhejs.net with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1muK6j-00012h-Ea; Mon, 06 Dec 2021 20:57:05 +0100 From: "Maciej S. Szmigiero" To: Paolo Bonzini , Sean Christopherson Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Igor Mammedov , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , Huacai Chen , Aleksandar Markovic , Paul Mackerras , Christian Borntraeger , Janosch Frank , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandru Elisei , Ben Gardon , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v7 27/29] KVM: Optimize overlapping memslots check Date: Mon, 6 Dec 2021 20:54:33 +0100 Message-Id: X-Mailer: git-send-email 2.33.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: "Maciej S. Szmigiero" Do a quick lookup for possibly overlapping gfns when creating or moving a memslot instead of performing a linear scan of the whole memslot set. Signed-off-by: Maciej S. Szmigiero [sean: tweaked params to avoid churn in future cleanup] Reviewed-by: Sean Christopherson --- virt/kvm/kvm_main.c | 36 ++++++++++++++++++++++-------------- 1 file changed, 22 insertions(+), 14 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 086f18969bc3..4cb97b31eac5 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1817,6 +1817,19 @@ static int kvm_set_memslot(struct kvm *kvm, return 0; } +static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id, + gfn_t start, gfn_t end) +{ + struct kvm_memslot_iter iter; + + kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end) { + if (iter.slot->id != id) + return true; + } + + return false; +} + /* * Allocate some memory and give it an address in the guest physical address * space. @@ -1828,8 +1841,9 @@ static int kvm_set_memslot(struct kvm *kvm, int __kvm_set_memory_region(struct kvm *kvm, const struct kvm_userspace_memory_region *mem) { - struct kvm_memory_slot *old, *tmp; + struct kvm_memory_slot *old; struct kvm_memory_slot new; + struct kvm_memslots *slots; enum kvm_mr_change change; int as_id, id; int r; @@ -1858,11 +1872,13 @@ int __kvm_set_memory_region(struct kvm *kvm, if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr) return -EINVAL; + slots = __kvm_memslots(kvm, as_id); + /* * Note, the old memslot (and the pointer itself!) may be invalidated * and/or destroyed by kvm_set_memslot(). */ - old = id_to_memslot(__kvm_memslots(kvm, as_id), id); + old = id_to_memslot(slots, id); if (!mem->memory_size) { if (!old || !old->npages) @@ -1911,18 +1927,10 @@ int __kvm_set_memory_region(struct kvm *kvm, return 0; } - if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) { - int bkt; - - /* Check for overlaps */ - kvm_for_each_memslot(tmp, bkt, __kvm_memslots(kvm, as_id)) { - if (tmp->id == id) - continue; - if (!((new.base_gfn + new.npages <= tmp->base_gfn) || - (new.base_gfn >= tmp->base_gfn + tmp->npages))) - return -EEXIST; - } - } + if ((change == KVM_MR_CREATE || change == KVM_MR_MOVE) && + kvm_check_memslot_overlap(slots, id, new.base_gfn, + new.base_gfn + new.npages)) + return -EEXIST; return kvm_set_memslot(kvm, old, &new, change); }