From patchwork Thu Oct 24 23:07:44 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 1183636 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=kvm-ppc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=intel.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 46zjZx702sz9sS8 for ; Fri, 25 Oct 2019 10:08:09 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387581AbfJXXIH (ORCPT ); Thu, 24 Oct 2019 19:08:07 -0400 Received: from mga18.intel.com ([134.134.136.126]:23485 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387595AbfJXXHy (ORCPT ); Thu, 24 Oct 2019 19:07:54 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Oct 2019 16:07:47 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,226,1569308400"; d="scan'208";a="202445874" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.41]) by orsmga006.jf.intel.com with ESMTP; 24 Oct 2019 16:07:46 -0700 From: Sean Christopherson To: James Hogan , Paul Mackerras , Christian Borntraeger , Janosch Frank , Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= , Marc Zyngier Cc: David Hildenbrand , Cornelia Huck , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , James Morse , Julien Thierry , Suzuki K Poulose , linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, Christoffer Dall Subject: [PATCH v3 15/15] KVM: Dynamically size memslot array based on number of used slots Date: Thu, 24 Oct 2019 16:07:44 -0700 Message-Id: <20191024230744.14543-16-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20191024230744.14543-1-sean.j.christopherson@intel.com> References: <20191024230744.14543-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org Now that the memslot logic doesn't assume memslots are always non-NULL, dynamically size the array of memslots instead of unconditionally allocating memory for the maximum number of memslots. Note, because a to-be-deleted memslot must first be invalidated, the array size cannot be immediately reduced when deleting a memslot. However, consecutive deletions will realize the memory savings, i.e. a second deletion will trim the entry. Tested-by: Christoffer Dall Signed-off-by: Sean Christopherson --- include/linux/kvm_host.h | 2 +- virt/kvm/kvm_main.c | 31 ++++++++++++++++++++++++++++--- 2 files changed, 29 insertions(+), 4 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index b5d4133a11e1..2d73b6e5fe6e 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -432,11 +432,11 @@ static inline int kvm_arch_vcpu_memslots_id(struct kvm_vcpu *vcpu) */ struct kvm_memslots { u64 generation; - struct kvm_memory_slot memslots[KVM_MEM_SLOTS_NUM]; /* The mapping table from slot id to the index in memslots[]. */ short id_to_index[KVM_MEM_SLOTS_NUM]; atomic_t lru_slot; int used_slots; + struct kvm_memory_slot memslots[]; }; struct kvm { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 7bc88375cf53..7dd02ee6ef95 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -535,7 +535,7 @@ static struct kvm_memslots *kvm_alloc_memslots(void) return NULL; for (i = 0; i < KVM_MEM_SLOTS_NUM; i++) - slots->id_to_index[i] = slots->memslots[i].id = -1; + slots->id_to_index[i] = -1; return slots; } @@ -1015,6 +1015,32 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm, return old_memslots; } +/* + * Note, at a minimum, the current number of used slots must be allocated, even + * when deleting a memslot, as we need a complete duplicate of the memslots for + * use when invalidating a memslot prior to deleting/moving the memslot. + */ +static struct kvm_memslots *kvm_dup_memslots(struct kvm_memslots *old, + enum kvm_mr_change change) +{ + struct kvm_memslots *slots; + size_t old_size, new_size; + + old_size = sizeof(struct kvm_memslots) + + (sizeof(struct kvm_memory_slot) * old->used_slots); + + if (change == KVM_MR_CREATE) + new_size = old_size + sizeof(struct kvm_memory_slot); + else + new_size = old_size; + + slots = kvzalloc(new_size, GFP_KERNEL_ACCOUNT); + if (likely(slots)) + memcpy(slots, old, old_size); + + return slots; +} + static int kvm_set_memslot(struct kvm *kvm, const struct kvm_userspace_memory_region *mem, const struct kvm_memory_slot *old, @@ -1025,10 +1051,9 @@ static int kvm_set_memslot(struct kvm *kvm, struct kvm_memslots *slots; int r; - slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT); + slots = kvm_dup_memslots(__kvm_memslots(kvm, as_id), change); if (!slots) return -ENOMEM; - memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots)); if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) { /*