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bh=RplG+uxLodzVSAra+BLtEv1oyAQOde6fur659vAR3Js=; b=Ye/IgORNfiGRqLgNdprFB3JlaGDNfAZM0AXwTAuqVajGFkU0GG4QxedRVK8Awihpu8izny NTe09+S34E7Jeu7PR+20Qqa8zEngkZxYRno0j3CauJKICbMZUclGnTKnX83vc4aLLqN4ua qwMCj7xp7ggllDEHpVlnzyGNh0mkF8M= 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-586-CHMMmErQP0OUuYTcsE1ZWQ-1; Fri, 18 Dec 2020 11:51:29 -0500 X-MC-Unique: CHMMmErQP0OUuYTcsE1ZWQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9F539190B2AF; Fri, 18 Dec 2020 16:51:27 +0000 (UTC) Received: from gondolin (ovpn-113-130.ams2.redhat.com [10.36.113.130]) by smtp.corp.redhat.com (Postfix) with ESMTP id 535545C233; Fri, 18 Dec 2020 16:51:22 +0000 (UTC) Date: Fri, 18 Dec 2020 17:51:19 +0100 From: Cornelia Huck To: Pierre Morel Subject: Re: [PATCH v2 2/2] s390x/pci: Fix memory_region_access_valid call Message-ID: <20201218175119.5f43b378.cohuck@redhat.com> In-Reply-To: <52c93c12-b9a4-99ba-186c-4db2e6267b9f@linux.ibm.com> References: <1608243397-29428-1-git-send-email-mjrosato@linux.ibm.com> <1608243397-29428-3-git-send-email-mjrosato@linux.ibm.com> <72f4e03f-7208-6af0-4cd2-9715d9f9ec77@linux.ibm.com> <20201218120440.36b56e80.cohuck@redhat.com> <2c5a2ccb-dbe1-f355-3980-462be1d93942@linux.ibm.com> <20201218163206.7b8efa2a.cohuck@redhat.com> <52c93c12-b9a4-99ba-186c-4db2e6267b9f@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: thuth@redhat.com, Matthew Rosato , david@redhat.com, richard.henderson@linaro.org, qemu-devel@nongnu.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, qemu-s390x@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, 18 Dec 2020 17:40:50 +0100 Pierre Morel wrote: > On 12/18/20 4:32 PM, Cornelia Huck wrote: > > On Fri, 18 Dec 2020 15:32:08 +0100 > > Pierre Morel wrote: > > > >> On 12/18/20 12:04 PM, Cornelia Huck wrote: > >>> On Fri, 18 Dec 2020 10:37:38 +0100 > >>> Pierre Morel wrote: > >>> > >>>> On 12/17/20 11:16 PM, Matthew Rosato wrote: > >>>>> In pcistb_service_handler, a call is made to validate that the memory > >>>>> region can be accessed. However, the call is made using the entire length > >>>>> of the pcistb operation, which can be larger than the allowed memory > >>>>> access size (8). Since we already know that the provided buffer is a > >>>>> multiple of 8, fix the call to memory_region_access_valid to iterate > >>>>> over the memory region in the same way as the subsequent call to > >>>>> memory_region_dispatch_write. > >>>>> > >>>>> Fixes: 863f6f52b7 ("s390: implement pci instructions") > >>>>> Signed-off-by: Matthew Rosato > >>>>> --- > >>>>> hw/s390x/s390-pci-inst.c | 10 ++++++---- > >>>>> 1 file changed, 6 insertions(+), 4 deletions(-) > >>>>> > >>>>> diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c > >>>>> index e230293..76b08a3 100644 > >>>>> --- a/hw/s390x/s390-pci-inst.c > >>>>> +++ b/hw/s390x/s390-pci-inst.c > >>>>> @@ -821,10 +821,12 @@ int pcistb_service_call(S390CPU *cpu, uint8_t r1, uint8_t r3, uint64_t gaddr, > >>>>> mr = s390_get_subregion(mr, offset, len); > >>>>> offset -= mr->addr; > >>>>> > >>>>> - if (!memory_region_access_valid(mr, offset, len, true, > >>>>> - MEMTXATTRS_UNSPECIFIED)) { > >>>>> - s390_program_interrupt(env, PGM_OPERAND, ra); > >>>>> - return 0; > >>>>> + for (i = 0; i < len; i += 8) { > >>>>> + if (!memory_region_access_valid(mr, offset + i, 8, true, > >>>>> + MEMTXATTRS_UNSPECIFIED)) { > >>>>> + s390_program_interrupt(env, PGM_OPERAND, ra); > >>>>> + return 0; > >>>>> + } > >>>>> } > >>>>> > >>>>> if (s390_cpu_virt_mem_read(cpu, gaddr, ar, buffer, len)) { > >>>>> > >>>> > >>>> wouldn't it be made automatically by defining the io_region > >>>> max_access_size when reading the bars in clp_service_call? > >>>> > >>> > >>> But that's already what is happening, isn't it? The access check is > >>> done for a size that is potentially too large, while the actual access > >>> will happen in chunks of 8? I think that this patch is correct. > >>> > >> > >> Sorry I was too rapid and half wrong in my writing I was also not > >> specific enough. > >> > >> In MemoryRegionOps we have a field valid with a callback accepts(). > >> > >> I was wondering if doing the check in the accept() callback which is > >> called by the memory_region_access_valid() function and then using > >> max_access_size would not be cleaner. > >> > >> Note that it does not change a lot but only where the check is done. > > > > But where would we add those ops? My understanding is that pcistb acts > > on whatever region the device provided, and that differs from device to > > device? > > > > > > The ops already exist, I thought adding a dedicated callback for s390 on > every regions used by vfio_pci instead of the default. > But it does not add a lot, just looks cleaner to me. But we end up here for every pci device, not just for vfio devices, don't we?