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 X-Spam-Level: X-Spam-Status: No, score=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C94DC433F5 for ; Wed, 15 Sep 2021 21:55:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2813604E9 for ; Wed, 15 Sep 2021 21:55:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232196AbhIOV4h (ORCPT ); Wed, 15 Sep 2021 17:56:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229543AbhIOV4f (ORCPT ); Wed, 15 Sep 2021 17:56:35 -0400 Received: from mail-io1-xd32.google.com (mail-io1-xd32.google.com [IPv6:2607:f8b0:4864:20::d32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 662C9C061574 for ; Wed, 15 Sep 2021 14:55:15 -0700 (PDT) Received: by mail-io1-xd32.google.com with SMTP id b200so5392448iof.13 for ; Wed, 15 Sep 2021 14:55:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=nBrJ+himGBxxi4AYbh7qI25DuiLu4lSxjn/yGNO9s04=; b=mtre4tgf60/KeYM+tgme6BjszuZBTn4nWSGxuGAQqi3zN29JTf4sUc1+cmjcb7UAlk G2FlxBug7tJlqAowsOnxmGhegd5Fu0FVSdi9lcoikegRf7e8rlwaZFgIReJrIdXNuQiQ BpktZtfb/MQ4aLbvJZeFPnJNN89W7hOb3YeGx5BoGNwYT2vaZJr7MJYwpPUv+VhzF0lK FwjoKR5vAvey+wFsKnrFKFY+cgXu62Q9YfmrC17OSHZcegPg1l7U5WsdjK8A83d8AmJc Ct3rwvTsCmAvdbqfIVN5wTe2DycLOyLJsCe1cJnC5FqzP72x2EdBYDjfsTXajTXh5iyJ yEOg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=nBrJ+himGBxxi4AYbh7qI25DuiLu4lSxjn/yGNO9s04=; b=JR/4/17elyeiUgjdRsR1IINVx8XeX4uD0u+9kwpnbrHzmbfmSFRdAf8H2wclmWhF/7 g9ZLA795hYVuXmq+AWhpkcqOJo4W3UOesa2fk+xJHioVpqWQLlycntLTt/jop9a/0yDd n0qaGLr5ZGKtTtYDnCa4yuxI991aJOl2dVsTHp//nB0hgWmFdg28hDbMswevoZLhsFO1 SVQym0bBQL5unKdcmN3clAv1q3GgxRaVjjfcUFKBhmB/CGEnAwhtrzWDL1ErypnMFOW/ PZ8cUGtcOImYfZ0rkEN0/UFtFGet6FMnfjXgrzltMPulrQqmx/U2DLMPTNy4B6OdrPIZ De7w== X-Gm-Message-State: AOAM532T1ysmnyZOHfXsHl+Dr/5v5djDKetQs7JowEVHswRC2wL4rl0r 83F4Px/VZCY140sFhiuo4N7E5ASP+uLeKiLrgAuEZGEhdo4= X-Google-Smtp-Source: ABdhPJxmwekqDWWSm390j9zcfEfsiu+UvHo2wMFvO40obck7jVBl72HBNGa9L6nQSxfbieTzlHOpt6/RJ27adpwC2so= X-Received: by 2002:a6b:ba42:: with SMTP id k63mr1784616iof.37.1631742914594; Wed, 15 Sep 2021 14:55:14 -0700 (PDT) MIME-Version: 1.0 References: <20210915213034.1613552-1-dmatlack@google.com> <20210915213034.1613552-4-dmatlack@google.com> In-Reply-To: <20210915213034.1613552-4-dmatlack@google.com> From: Ben Gardon Date: Wed, 15 Sep 2021 14:55:03 -0700 Message-ID: Subject: Re: [PATCH 3/3] KVM: selftests: Fix dirty bitmap offset calculation To: David Matlack Cc: Paolo Bonzini , kvm , Andrew Jones , Axel Rasmussen , Yanan Wang Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Sep 15, 2021 at 2:30 PM David Matlack wrote: > > The calculation to get the per-slot dirty bitmap was incorrect leading > to a buffer overrun. Fix it by dividing the number of pages by > BITS_PER_LONG, since each element of the bitmap is a long and there is > one bit per page. > > Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test") > Signed-off-by: David Matlack I was a little confused initially because we're allocating only one dirty bitmap in userspace even when we have multiple slots, but that's not a problem. Reviewed-by: Ben Gardon > > --- > tools/testing/selftests/kvm/dirty_log_perf_test.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c > index 5ad9f2bc7369..0dd4626571e9 100644 > --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c > +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c > @@ -118,6 +118,12 @@ static inline void disable_dirty_logging(struct kvm_vm *vm, int slots) > toggle_dirty_logging(vm, slots, false); > } > > +static unsigned long *get_slot_bitmap(unsigned long *bitmap, uint64_t page_offset) > +{ > + /* Guaranteed to be evenly divisible by the TEST_ASSERT in run_test. */ > + return &bitmap[page_offset / BITS_PER_LONG]; > +} > + > static void get_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap, > uint64_t nr_pages) > { > @@ -126,7 +132,8 @@ static void get_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap, > > for (i = 0; i < slots; i++) { > int slot = PERF_TEST_MEM_SLOT_INDEX + i; > - unsigned long *slot_bitmap = bitmap + i * slot_pages; > + uint64_t page_offset = slot_pages * i; > + unsigned long *slot_bitmap = get_slot_bitmap(bitmap, page_offset); > > kvm_vm_get_dirty_log(vm, slot, slot_bitmap); > } > @@ -140,7 +147,8 @@ static void clear_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap, > > for (i = 0; i < slots; i++) { > int slot = PERF_TEST_MEM_SLOT_INDEX + i; > - unsigned long *slot_bitmap = bitmap + i * slot_pages; > + uint64_t page_offset = slot_pages * i; > + unsigned long *slot_bitmap = get_slot_bitmap(bitmap, page_offset); > > kvm_vm_clear_dirty_log(vm, slot, slot_bitmap, 0, slot_pages); > } > @@ -172,6 +180,9 @@ static void run_test(enum vm_guest_mode mode, void *arg) > guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages); > host_num_pages = vm_num_host_pages(mode, guest_num_pages); > bmap = bitmap_alloc(host_num_pages); > + TEST_ASSERT((host_num_pages / p->slots) % BITS_PER_LONG == 0, > + "The number of pages per slot must be divisible by %d.", > + BITS_PER_LONG); > > if (dirty_log_manual_caps) { > cap.cap = KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2; > -- > 2.33.0.309.g3052b89438-goog >