From patchwork Wed Sep 6 12:04:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13375618 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8AF15EB8FAF for ; Wed, 6 Sep 2023 12:05:47 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qdrHm-0003kF-RY; Wed, 06 Sep 2023 08:05:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qdrHc-0003fY-JN for qemu-devel@nongnu.org; Wed, 06 Sep 2023 08:05:21 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qdrHa-0006lg-5w for qemu-devel@nongnu.org; Wed, 06 Sep 2023 08:05:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1694001917; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OYmUdM9xnUxYUikMjy3S8zQ+vg85pGF8BhztC9qJ42Y=; b=Bbb+bccix/rh+XAdhZugEMVYJL5pGMU7TadjtJQXoZDAG1F1iy0kV0OPfPXu/xEbQavAW/ ZHKiASJdoypaCgC5Fo5/XxS2EJx/o+s/7CoTSQtgmAHG65xFHLeRtMmHpBIiQcRauuBQ5H gMTsMmUWVzlYNewIwLedF776krt3QRw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-218-Ob4T9TtSN2uGEVeMRVmatQ-1; Wed, 06 Sep 2023 08:05:12 -0400 X-MC-Unique: Ob4T9TtSN2uGEVeMRVmatQ-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B81FA8AA803; Wed, 6 Sep 2023 12:05:10 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.39.192.60]) by smtp.corp.redhat.com (Postfix) with ESMTP id AB274493112; Wed, 6 Sep 2023 12:05:07 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Cc: David Hildenbrand , Paolo Bonzini , Peter Xu , Igor Mammedov , Thiner Logoer , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= , =?utf-8?q?Daniel_P_=2E_Berrang?= =?utf-8?q?=C3=A9?= , Stefan Hajnoczi , Elena Ufimtseva , Jagannathan Raman , "Michael S. Tsirkin" , Ani Sinha , Xiao Guangrong , Daniel Henrique Barboza , Greg Kurz , Eric Blake , Markus Armbruster , Eduardo Habkost Subject: [PATCH v4 01/11] nvdimm: Reject writing label data to ROM instead of crashing QEMU Date: Wed, 6 Sep 2023 14:04:53 +0200 Message-ID: <20230906120503.359863-2-david@redhat.com> In-Reply-To: <20230906120503.359863-1-david@redhat.com> References: <20230906120503.359863-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.133.124; envelope-from=david@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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Currently, when using a true R/O NVDIMM (ROM memory backend) with a label area, the VM can easily crash QEMU by trying to write to the label area, because the ROM memory is mmap'ed without PROT_WRITE. [root@vm-0 ~]# ndctl disable-region region0 disabled 1 region [root@vm-0 ~]# ndctl zero-labels nmem0 -> QEMU segfaults Let's remember whether we have a ROM memory backend and properly reject the write request: [root@vm-0 ~]# ndctl disable-region region0 disabled 1 region [root@vm-0 ~]# ndctl zero-labels nmem0 zeroed 0 nmem In comparison, on a system with a R/W NVDIMM: [root@vm-0 ~]# ndctl disable-region region0 disabled 1 region [root@vm-0 ~]# ndctl zero-labels nmem0 zeroed 1 nmem For ACPI, just return "unsupported", like if no label exists. For spapr, return "H_P2", similar to when no label area exists. Could we rely on the "unarmed" property? Maybe, but it looks cleaner to only disallow what certainly cannot work. After all "unarmed=on" primarily means: cannot accept persistent writes. In theory, there might be setups where devices with "unarmed=on" set could be used to host non-persistent data (temporary files, system RAM, ...); for example, in Linux, admins can overwrite the "readonly" setting and still write to the device -- which will work as long as we're not using ROM. Allowing writing label data in such configurations can make sense. Fixes: dbd730e85987 ("nvdimm: check -object memory-backend-file, readonly=on option") Reviewed-by: Stefan Hajnoczi Signed-off-by: David Hildenbrand --- hw/acpi/nvdimm.c | 11 ++++++++--- hw/mem/nvdimm.c | 10 +++++++--- hw/ppc/spapr_nvdimm.c | 3 ++- include/hw/mem/nvdimm.h | 6 ++++++ 4 files changed, 23 insertions(+), 7 deletions(-) diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c index a3b25a92f3..3cbd41629d 100644 --- a/hw/acpi/nvdimm.c +++ b/hw/acpi/nvdimm.c @@ -670,7 +670,8 @@ static void nvdimm_dsm_label_size(NVDIMMDevice *nvdimm, hwaddr dsm_mem_addr) } static uint32_t nvdimm_rw_label_data_check(NVDIMMDevice *nvdimm, - uint32_t offset, uint32_t length) + uint32_t offset, uint32_t length, + bool is_write) { uint32_t ret = NVDIMM_DSM_RET_STATUS_INVALID; @@ -690,6 +691,10 @@ static uint32_t nvdimm_rw_label_data_check(NVDIMMDevice *nvdimm, return ret; } + if (is_write && nvdimm->readonly) { + return NVDIMM_DSM_RET_STATUS_UNSUPPORT; + } + return NVDIMM_DSM_RET_STATUS_SUCCESS; } @@ -713,7 +718,7 @@ static void nvdimm_dsm_get_label_data(NVDIMMDevice *nvdimm, NvdimmDsmIn *in, get_label_data->length); status = nvdimm_rw_label_data_check(nvdimm, get_label_data->offset, - get_label_data->length); + get_label_data->length, false); if (status != NVDIMM_DSM_RET_STATUS_SUCCESS) { nvdimm_dsm_no_payload(status, dsm_mem_addr); return; @@ -752,7 +757,7 @@ static void nvdimm_dsm_set_label_data(NVDIMMDevice *nvdimm, NvdimmDsmIn *in, set_label_data->length); status = nvdimm_rw_label_data_check(nvdimm, set_label_data->offset, - set_label_data->length); + set_label_data->length, true); if (status != NVDIMM_DSM_RET_STATUS_SUCCESS) { nvdimm_dsm_no_payload(status, dsm_mem_addr); return; diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c index 31080c22c9..1631a7d13f 100644 --- a/hw/mem/nvdimm.c +++ b/hw/mem/nvdimm.c @@ -154,6 +154,9 @@ static void nvdimm_prepare_memory_region(NVDIMMDevice *nvdimm, Error **errp) object_get_canonical_path_component(OBJECT(hostmem))); return; } + if (memory_region_is_rom(mr)) { + nvdimm->readonly = true; + } nvdimm->nvdimm_mr = g_new(MemoryRegion, 1); memory_region_init_alias(nvdimm->nvdimm_mr, OBJECT(dimm), @@ -207,15 +210,16 @@ static void nvdimm_unrealize(PCDIMMDevice *dimm) * label read/write functions. */ static void nvdimm_validate_rw_label_data(NVDIMMDevice *nvdimm, uint64_t size, - uint64_t offset) + uint64_t offset, bool is_write) { assert((nvdimm->label_size >= size + offset) && (offset + size > offset)); + assert(!is_write || !nvdimm->readonly); } static void nvdimm_read_label_data(NVDIMMDevice *nvdimm, void *buf, uint64_t size, uint64_t offset) { - nvdimm_validate_rw_label_data(nvdimm, size, offset); + nvdimm_validate_rw_label_data(nvdimm, size, offset, false); memcpy(buf, nvdimm->label_data + offset, size); } @@ -229,7 +233,7 @@ static void nvdimm_write_label_data(NVDIMMDevice *nvdimm, const void *buf, "pmem", NULL); uint64_t backend_offset; - nvdimm_validate_rw_label_data(nvdimm, size, offset); + nvdimm_validate_rw_label_data(nvdimm, size, offset, true); if (!is_pmem) { memcpy(nvdimm->label_data + offset, buf, size); diff --git a/hw/ppc/spapr_nvdimm.c b/hw/ppc/spapr_nvdimm.c index a8688243a6..60d6d0acc0 100644 --- a/hw/ppc/spapr_nvdimm.c +++ b/hw/ppc/spapr_nvdimm.c @@ -320,7 +320,8 @@ static target_ulong h_scm_write_metadata(PowerPCCPU *cpu, nvdimm = NVDIMM(drc->dev); if ((offset + len < offset) || - (nvdimm->label_size < len + offset)) { + (nvdimm->label_size < len + offset) || + nvdimm->readonly) { return H_P2; } diff --git a/include/hw/mem/nvdimm.h b/include/hw/mem/nvdimm.h index acf887c83d..d3b763453a 100644 --- a/include/hw/mem/nvdimm.h +++ b/include/hw/mem/nvdimm.h @@ -77,6 +77,12 @@ struct NVDIMMDevice { */ bool unarmed; + /* + * Whether our DIMM is backed by ROM, and even label data cannot be + * written. If set, implies that "unarmed" is also set. + */ + bool readonly; + /* * The PPC64 - spapr requires each nvdimm device have a uuid. */