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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2604BC77B75 for ; Tue, 18 Apr 2023 17:52:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231793AbjDRRwq (ORCPT ); Tue, 18 Apr 2023 13:52:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33698 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231432AbjDRRwn (ORCPT ); Tue, 18 Apr 2023 13:52:43 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CCB91B45C; Tue, 18 Apr 2023 10:52:15 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5E30562CD5; Tue, 18 Apr 2023 17:52:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EB764C433D2; Tue, 18 Apr 2023 17:52:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1681840334; bh=za1o6VU2W+1EIlPlbU3wstltJzV9dcg9Lopt3PW9kmM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SvOVsXMygNxTEp9k7Wj/s/hUUN8YX7V8VxpGwhKUSynCvUC7/ixbWVXJyvcwljW6E w1rImy+t4HaXTEZs84/pNB9Dgu0MV1VCMg23uoNUKVk1IgmibJa2U2V2K6oCRd4bDE 1EfeV9Y8EwW5X2M3QR1Fq08uYWzSkk7eIQUhnMiMhx3CxwIQRZwSvYgSujN2xO+mAu 7wI1z1xFLLgMfeS0FSqFPSovvextNNQoiGmAv103OFTB+Ex4GU24HfM8p61qewXFIj VjMojg6+fJsKQD60Ul9RDX3dGz+ZdNFLuL92YS7XHWGB2SAv+avwCimzhsBotl6HeN fvRcJZkVw45yA== Date: Tue, 18 Apr 2023 19:52:09 +0200 From: Simon Horman To: Stefan Berger Cc: kexec@lists.infradead.org, devicetree@vger.kernel.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, nayna@linux.ibm.com, nasastry@in.ibm.com, mpe@ellerman.id.au, Rob Herring , Frank Rowand , Eric Biederman , Nageswara R Sastry , Coiby Xu , Rob Herring Subject: Re: [PATCH v9 4/4] tpm/kexec: Duplicate TPM measurement log in of-tree for kexec Message-ID: References: <20230418134409.177485-1-stefanb@linux.ibm.com> <20230418134409.177485-5-stefanb@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230418134409.177485-5-stefanb@linux.ibm.com> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Tue, Apr 18, 2023 at 09:44:09AM -0400, Stefan Berger wrote: > The memory area of the TPM measurement log is currently not properly > duplicated for carrying it across kexec when an Open Firmware > Devicetree is used. Therefore, the contents of the log get corrupted. > Fix this for the kexec_file_load() syscall by allocating a buffer and > copying the contents of the existing log into it. The new buffer is > preserved across the kexec and a pointer to it is available when the new > kernel is started. To achieve this, store the allocated buffer's address > in the flattened device tree (fdt) under the name linux,tpm-kexec-buffer > and search for this entry early in the kernel startup before the TPM > subsystem starts up. Adjust the pointer in the of-tree stored under > linux,sml-base to point to this buffer holding the preserved log. The TPM > driver can then read the base address from this entry when making the log > available. Invalidate the log by removing 'linux,sml-base' from the > devicetree if anything goes wrong with updating the buffer. > > Use subsys_initcall() to call the function to restore the buffer even if > the TPM subsystem or driver are not used. This allows the buffer to be > carried across the next kexec without involvement of the TPM subsystem > and ensures a valid buffer pointed to by the of-tree. Hi Stefan, some minor feedback from my side. > Use the subsys_initcall(), rather than an ealier initcall, since nit via checkpatch.pl --codespell: s/ealier/earlier/ > page_is_ram() in get_kexec_buffer() only starts working at this stage. > > Signed-off-by: Stefan Berger > Cc: Rob Herring > Cc: Frank Rowand > Cc: Eric Biederman > Tested-by: Nageswara R Sastry > Tested-by: Coiby Xu > Reviewed-by: Rob Herring ... > +void tpm_add_kexec_buffer(struct kimage *image) > +{ > + struct kexec_buf kbuf = { .image = image, .buf_align = 1, > + .buf_min = 0, .buf_max = ULONG_MAX, > + .top_down = true }; > + struct device_node *np; > + void *buffer; > + u32 size; > + u64 base; > + int ret; > + > + if (!IS_ENABLED(CONFIG_PPC64)) > + return; > + > + np = of_find_node_by_name(NULL, "vtpm"); > + if (!np) > + return; > + > + if (of_tpm_get_sml_parameters(np, &base, &size) < 0) > + return; > + > + buffer = vmalloc(size); > + if (!buffer) > + return; > + memcpy(buffer, __va(base), size); > + > + kbuf.buffer = buffer; > + kbuf.bufsz = size; > + kbuf.memsz = size; > + ret = kexec_add_buffer(&kbuf); > + if (ret) { > + pr_err("Error passing over kexec TPM measurement log buffer: %d\n", > + ret); Does buffer need to be freed here? > + return; > + } > + > + image->tpm_buffer = buffer; > + image->tpm_buffer_addr = kbuf.mem; > + image->tpm_buffer_size = size; > +}