From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752018AbdCPLGN (ORCPT ); Thu, 16 Mar 2017 07:06:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45714 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751431AbdCPLEK (ORCPT ); Thu, 16 Mar 2017 07:04:10 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 8B14C8124D Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=pbonzini@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 8B14C8124D Subject: Re: [RFC PATCH v2 30/32] kvm: svm: Add support for SEV DEBUG_ENCRYPT command To: Brijesh Singh , simon.guinot@sequanux.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, rkrcmar@redhat.com, matt@codeblueprint.co.uk, linux-pci@vger.kernel.org, linus.walleij@linaro.org, gary.hook@amd.com, linux-mm@kvack.org, paul.gortmaker@windriver.com, hpa@zytor.com, cl@linux.com, dan.j.williams@intel.com, aarcange@redhat.com, sfr@canb.auug.org.au, andriy.shevchenko@linux.intel.com, herbert@gondor.apana.org.au, bhe@redhat.com, xemul@parallels.com, joro@8bytes.org, x86@kernel.org, peterz@infradead.org, piotr.luc@intel.com, mingo@redhat.com, msalter@redhat.com, ross.zwisler@linux.intel.com, bp@suse.de, dyoung@redhat.com, thomas.lendacky@amd.com, jroedel@suse.de, keescook@chromium.org, arnd@arndb.de, toshi.kani@hpe.com, mathieu.desnoyers@efficios.com, luto@kernel.org, devel@linuxdriverproject.org, bhelgaas@google.com, tglx@linutronix.de, mchehab@kernel.org, iamjoonsoo.kim@lge.com, labbott@fedoraproject.org, tony.luck@intel.com, alexandre.bounine@idt.com, kuleshovmail@gmail.com, linux-kernel@vger.kernel.org, mcgrof@kernel.org, mst@redhat.com, linux-crypto@vger.kernel.org, tj@kernel.org, akpm@linux-foundation.org, davem@davemloft.net References: <148846752022.2349.13667498174822419498.stgit@brijesh-build-machine> <148846790758.2349.16768762953657853550.stgit@brijesh-build-machine> From: Paolo Bonzini Message-ID: <05dbd756-e8e9-9384-2759-898e230a6909@redhat.com> Date: Thu, 16 Mar 2017 12:03:52 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <148846790758.2349.16768762953657853550.stgit@brijesh-build-machine> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 16 Mar 2017 11:04:10 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/03/2017 16:18, Brijesh Singh wrote: > + data = (void *) get_zeroed_page(GFP_KERNEL); The page does not need to be zeroed, does it? > + > + if ((len & 15) || (dst_addr & 15)) { > + /* if destination address and length are not 16-byte > + * aligned then: > + * a) decrypt destination page into temporary buffer > + * b) copy source data into temporary buffer at correct offset > + * c) encrypt temporary buffer > + */ > + ret = __sev_dbg_decrypt_page(kvm, dst_addr, data, &argp->error); Ah, I see now you're using this function here for read-modify-write. data is already pinned here, so even if you keep the function it makes sense to push pinning out of __sev_dbg_decrypt_page and into sev_dbg_decrypt. > + if (ret) > + goto err_3; > + d_off = dst_addr & (PAGE_SIZE - 1); > + > + if (copy_from_user(data + d_off, > + (uint8_t *)debug.src_addr, len)) { > + ret = -EFAULT; > + goto err_3; > + } > + > + encrypt->length = PAGE_SIZE; Why decrypt/re-encrypt all the page instead of just the 16 byte area around the [dst_addr, dst_addr+len) range? > + encrypt->src_addr = __psp_pa(data); > + encrypt->dst_addr = __sev_page_pa(inpages[0]); > + } else { > + if (copy_from_user(data, (uint8_t *)debug.src_addr, len)) { > + ret = -EFAULT; > + goto err_3; > + } Do you need copy_from_user, or can you just pin/unpin memory as for DEBUG_DECRYPT? Paolo > + d_off = dst_addr & (PAGE_SIZE - 1); > + encrypt->length = len; > + encrypt->src_addr = __psp_pa(data); > + encrypt->dst_addr = __sev_page_pa(inpages[0]); > + encrypt->dst_addr += d_off; > + } > + > + encrypt->handle = sev_get_handle(kvm); > + ret = sev_issue_cmd(kvm, SEV_CMD_DBG_ENCRYPT, encrypt, &argp->error);