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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 BE76BC35646 for ; Fri, 21 Feb 2020 10:42:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 88A7A222C4 for ; Fri, 21 Feb 2020 10:42:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UAD5I7NC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727096AbgBUKmQ (ORCPT ); Fri, 21 Feb 2020 05:42:16 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:32808 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726325AbgBUKmQ (ORCPT ); Fri, 21 Feb 2020 05:42:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582281734; 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=SxUDH729ImYJWoEJ7OBwmWzajRZSSJWfF59Hr+aoows=; b=UAD5I7NCPFc16opvCWjL2WUS5nABV5qSYb8LO8pSLfc6tP1xQTj5UZIPvaRu/NSf+mG/l/ ka1FG1U34izq9q3sQpokNlPCiPz4bUeTwQb7q+OB3WNqRSVNXz6HDJlkhlK0GIDTCQKGe6 V0Y0eN6P9VZFmpNAbSwkkaNRLaieKCc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-33-LZqUQ3abOY2i8_yjgdAZLw-1; Fri, 21 Feb 2020 05:42:07 -0500 X-MC-Unique: LZqUQ3abOY2i8_yjgdAZLw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 447238017CC; Fri, 21 Feb 2020 10:42:05 +0000 (UTC) Received: from gondolin (dhcp-192-195.str.redhat.com [10.33.192.195]) by smtp.corp.redhat.com (Postfix) with ESMTP id DB2AD1001F43; Fri, 21 Feb 2020 10:42:00 +0000 (UTC) Date: Fri, 21 Feb 2020 11:41:58 +0100 From: Cornelia Huck To: Christian Borntraeger Cc: Ulrich.Weigand@de.ibm.com, david@redhat.com, frankja@linux.vnet.ibm.com, gor@linux.ibm.com, imbrenda@linux.ibm.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org, mimu@linux.ibm.com, thuth@redhat.com Subject: Re: [PATCH v3.1 02/37] KVM: s390/interrupt: do not pin adapter interrupt pages Message-ID: <20200221114158.2eeca512.cohuck@redhat.com> In-Reply-To: <20200221080942.10334-1-borntraeger@de.ibm.com> References: <20200220104020.5343-3-borntraeger@de.ibm.com> <20200221080942.10334-1-borntraeger@de.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, 21 Feb 2020 03:09:42 -0500 Christian Borntraeger wrote: > From: Ulrich Weigand > > The adapter interrupt page containing the indicator bits is currently > pinned. That means that a guest with many devices can pin a lot of > memory pages in the host. This also complicates the reference tracking > which is needed for memory management handling of protected virtual > machines. It might also have some strange side effects for madvise > MADV_DONTNEED and other things. > > We can simply try to get the userspace page set the bits and free the > page. By storing the userspace address in the irq routing entry instead > of the guest address we can actually avoid many lookups and list walks > so that this variant is very likely not slower. > > If userspace messes around with the memory slots the worst thing that > can happen is that we write to some other memory within that process. > As we get the the page with FOLL_WRITE this can also not be used to > write to shared read-only pages. > > Signed-off-by: Ulrich Weigand > [borntraeger@de.ibm.com: patch simplification] > Signed-off-by: Christian Borntraeger > --- > Documentation/virt/kvm/devices/s390_flic.rst | 11 +- > arch/s390/include/asm/kvm_host.h | 3 - > arch/s390/kvm/interrupt.c | 172 ++++++------------- > 3 files changed, 52 insertions(+), 134 deletions(-) (...) > @@ -2456,12 +2378,13 @@ static int modify_io_adapter(struct kvm_device *dev, > if (ret > 0) > ret = 0; > break; > + /* > + * We resolve the gpa to hva when setting the IRQ routing. the set_irq > + * code uses get_user_pages_remote() to do the actual write. > + */ What about: "The following operations are no longer needed and therefore no-ops. The gpa to hva translation is done when an IRQ route is set up. The set_irq code uses get_user_pages_remote() to do the actual write." > case KVM_S390_IO_ADAPTER_MAP: > - ret = kvm_s390_adapter_map(dev->kvm, req.id, req.addr); > - break; > case KVM_S390_IO_ADAPTER_UNMAP: > - ret = kvm_s390_adapter_unmap(dev->kvm, req.id, req.addr); > - break; > + return 0; I think ret = 0; break; would be better, as the other cases do not do a direct return, either. > default: > ret = -EINVAL; > } > @@ -2699,19 +2622,17 @@ static unsigned long get_ind_bit(__u64 addr, unsigned long bit_nr, bool swap) > return swap ? (bit ^ (BITS_PER_LONG - 1)) : bit; > } > > -static struct s390_map_info *get_map_info(struct s390_io_adapter *adapter, > - u64 addr) > +static struct page *get_map_page(struct kvm *kvm, > + struct s390_io_adapter *adapter, adapter seems to be unused in this function now? Should we remove it from the parameter list? > + u64 uaddr) > { > - struct s390_map_info *map; > - > - if (!adapter) > - return NULL; > + struct page *page = NULL; > > - list_for_each_entry(map, &adapter->maps, list) { > - if (map->guest_addr == addr) > - return map; > - } > - return NULL; > + down_read(&kvm->mm->mmap_sem); > + get_user_pages_remote(NULL, kvm->mm, uaddr, 1, FOLL_WRITE, > + &page, NULL, NULL); > + up_read(&kvm->mm->mmap_sem); > + return page; > } > > static int adapter_indicators_set(struct kvm *kvm, > @@ -2720,30 +2641,35 @@ static int adapter_indicators_set(struct kvm *kvm, > { > unsigned long bit; > int summary_set, idx; > - struct s390_map_info *info; > + struct page *ind_page, *summary_page; > void *map; > > - info = get_map_info(adapter, adapter_int->ind_addr); > - if (!info) > + ind_page = get_map_page(kvm, adapter, adapter_int->ind_addr); > + if (!ind_page) > return -1; > - map = page_address(info->page); > - bit = get_ind_bit(info->addr, adapter_int->ind_offset, adapter->swap); > - set_bit(bit, map); > - idx = srcu_read_lock(&kvm->srcu); > - mark_page_dirty(kvm, info->guest_addr >> PAGE_SHIFT); > - set_page_dirty_lock(info->page); > - info = get_map_info(adapter, adapter_int->summary_addr); > - if (!info) { > - srcu_read_unlock(&kvm->srcu, idx); > + summary_page = get_map_page(kvm, adapter, adapter_int->summary_addr); > + if (!summary_page) { > + put_page(ind_page); > return -1; > } > - map = page_address(info->page); > - bit = get_ind_bit(info->addr, adapter_int->summary_offset, > - adapter->swap); > + > + idx = srcu_read_lock(&kvm->srcu); > + map = page_address(ind_page); > + bit = get_ind_bit(adapter_int->ind_addr, > + adapter_int->ind_offset, adapter->swap); > + set_bit(bit, map); > + mark_page_dirty(kvm, adapter_int->ind_addr >> PAGE_SHIFT); > + set_page_dirty_lock(ind_page); > + map = page_address(summary_page); > + bit = get_ind_bit(adapter_int->summary_addr, > + adapter_int->summary_offset, adapter->swap); > summary_set = test_and_set_bit(bit, map); > - mark_page_dirty(kvm, info->guest_addr >> PAGE_SHIFT); > - set_page_dirty_lock(info->page); > + mark_page_dirty(kvm, adapter_int->summary_addr >> PAGE_SHIFT); > + set_page_dirty_lock(summary_page); > srcu_read_unlock(&kvm->srcu, idx); > + > + put_page(ind_page); > + put_page(summary_page); > return summary_set ? 0 : 1; > } > > @@ -2765,9 +2691,7 @@ static int set_adapter_int(struct kvm_kernel_irq_routing_entry *e, > adapter = get_io_adapter(kvm, e->adapter.adapter_id); > if (!adapter) > return -1; > - down_read(&adapter->maps_lock); > ret = adapter_indicators_set(kvm, adapter, &e->adapter); > - up_read(&adapter->maps_lock); > if ((ret > 0) && !adapter->masked) { > ret = kvm_s390_inject_airq(kvm, adapter); > if (ret == 0) > @@ -2818,23 +2742,27 @@ int kvm_set_routing_entry(struct kvm *kvm, > struct kvm_kernel_irq_routing_entry *e, > const struct kvm_irq_routing_entry *ue) > { > - int ret; > + u64 uaddr; > > switch (ue->type) { > + /* we store the userspace addresses instead of the guest addresses */ > case KVM_IRQ_ROUTING_S390_ADAPTER: > e->set = set_adapter_int; > - e->adapter.summary_addr = ue->u.adapter.summary_addr; > - e->adapter.ind_addr = ue->u.adapter.ind_addr; > + uaddr = gmap_translate(kvm->arch.gmap, ue->u.adapter.summary_addr); > + if (uaddr == -EFAULT) > + return -EFAULT; > + e->adapter.summary_addr = uaddr; > + uaddr = gmap_translate(kvm->arch.gmap, ue->u.adapter.ind_addr); > + if (uaddr == -EFAULT) > + return -EFAULT; > + e->adapter.ind_addr = uaddr; > e->adapter.summary_offset = ue->u.adapter.summary_offset; > e->adapter.ind_offset = ue->u.adapter.ind_offset; > e->adapter.adapter_id = ue->u.adapter.adapter_id; > - ret = 0; > - break; > + return 0; > default: > - ret = -EINVAL; > + return -EINVAL; > } > - > - return ret; > } > > int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e, struct kvm *kvm,