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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07807C4345F for ; Mon, 29 Apr 2024 14:27:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 593EE6B0085; Mon, 29 Apr 2024 10:27:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 543DA6B0089; Mon, 29 Apr 2024 10:27:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 40AF96B008A; Mon, 29 Apr 2024 10:27:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 20B276B0089 for ; Mon, 29 Apr 2024 10:27:58 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id CA37F1A10AE for ; Mon, 29 Apr 2024 14:27:57 +0000 (UTC) X-FDA: 82062798594.13.F7C0F52 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) by imf08.hostedemail.com (Postfix) with ESMTP id 536B5160037 for ; Mon, 29 Apr 2024 14:27:25 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=J4YcLb2E; spf=pass (imf08.hostedemail.com: domain of 3S64vZgYKCJ4QC8LHAEMMEJC.AMKJGLSV-KKIT8AI.MPE@flex--seanjc.bounces.google.com designates 209.85.215.201 as permitted sender) smtp.mailfrom=3S64vZgYKCJ4QC8LHAEMMEJC.AMKJGLSV-KKIT8AI.MPE@flex--seanjc.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1714400845; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=S3mlM0E1TrjvYHfesQNSkr38bw44gyQq8z5XmrX3EV0=; b=Ng4dc0TtpAsA+FGElc5hicEoRYKoc5hFNDV1igFlkCmfKmfuly7UQND+Zle8AAbV2am1wQ bceLLhh7o7SzNF6m7xhjzs7F46e6TgK2ElbhtTPGRoAEcsHxLFu/Ua+KxMoToWPfMysUMC f2nzBw+eAM0ZkZoeos8km/Hlqn0Nfnk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1714400845; a=rsa-sha256; cv=none; b=qea2bVI5xbTUE98mrcGRdOSl5OsHJvnGs+/CvKanroaMU7pNqEmLibjcSYSzepw637hfpa 48NTPHhLTmucWimn6KesE3Z14HtRaYfOz2tXxDTKR5YzGVD0h2gN4Abb6IRwJPsZw+nfZ0 uV+Faz7OQpsAqMcXQwN/kQPqWHXf5vU= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=J4YcLb2E; spf=pass (imf08.hostedemail.com: domain of 3S64vZgYKCJ4QC8LHAEMMEJC.AMKJGLSV-KKIT8AI.MPE@flex--seanjc.bounces.google.com designates 209.85.215.201 as permitted sender) smtp.mailfrom=3S64vZgYKCJ4QC8LHAEMMEJC.AMKJGLSV-KKIT8AI.MPE@flex--seanjc.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-601fef07eaeso5218464a12.1 for ; Mon, 29 Apr 2024 07:27:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1714400844; x=1715005644; darn=kvack.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=S3mlM0E1TrjvYHfesQNSkr38bw44gyQq8z5XmrX3EV0=; b=J4YcLb2EQafJutjnT5PFwih+UO1e+AMMtTDpvBSxoSQyBRSMBMMJnyDfhoDjRiabEG 9rW7XcWR6wutFSqzD6een9gfYaxmOmXV7LSrwHo+/lodS3gOq+3Ts1AKrLjbe33AjpHd y5jweYJUAdlK51QW6UaIVb+vE/IPSQLmLsnRDiE47T4qd4RzI+SE6z/2LNZCROVpIZZX OdlhnB8/jLbSZ/xmf3ur+9upbI6bJD7xiOpC94BsMzygCjIU87uY4+WxqWr8uamgWKiu mZWQDFwZLUACpMqWMt5cnAVMQpizerjwV/ajwh8+cGfDWde9lpd52dhDcCpBIl4O52ie v5Jg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1714400844; x=1715005644; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=S3mlM0E1TrjvYHfesQNSkr38bw44gyQq8z5XmrX3EV0=; b=TxlY09nHH2a2+V+vHAeQNfe753R+LMUFr84p5sYkU51msCaEorTLgHQDsUVLCxPX3h S1tNANtX40y/m230rj4d6cjr9Z2TNNBqbnr5iGTUmb5EKvVOnfryo9sUQWCBgvuveSx5 Rlv+Jzt9MLoCyr46AnIxbUqkWB2Z8IcMpyHV82ugoV056tGUhbA5MqUYkx1FT2xPvrbJ aY+OCF0fo7gPAtuZBYDUWrS+dWJYhABAxcWL4syk/v32fE+o5vzYmr8ivmmOLhzfl6Bl 0RLeEowWwUo4OlgEZ9J7nrMlRvF41VpmIGyGA8bUmYEIEsYLnIsAOSDDQO/9R42DIoj5 gGAA== X-Forwarded-Encrypted: i=1; AJvYcCUmjNCoj8zQ2QRnjcsugQTu7y5cMnH0WyCTRbdjBMe8kS1akjkbZC9NbCIv+NOW0KgUw8n8dxF//2dLlZDITJ6/WEc= X-Gm-Message-State: AOJu0Ywc0nBvftS+tai7ZmnyXGOOnrOUe0E2QkMfCCO+n/CJkf9o0g4n /ztmUwbk9aprdkGYZ4PvZk44PSBZLEX9DPlMQb4wndR20F2F+eDy/lH0omV/eR4f4UnwpsFO+aq Vjg== X-Google-Smtp-Source: AGHT+IFtI1VRsJxmoBaQkkMNkidpPOTCEAStMWY3Kr4rNLpPFTYg7KKAfEudEOmt/GvfkLL4yDTV9xTdh4k= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a63:1e5d:0:b0:5f7:651b:fed8 with SMTP id p29-20020a631e5d000000b005f7651bfed8mr29463pgm.12.1714400843944; Mon, 29 Apr 2024 07:27:23 -0700 (PDT) Date: Mon, 29 Apr 2024 07:27:22 -0700 In-Reply-To: <20240427013210.ioz7mv3yuu2r5un6@amd.com> Mime-Version: 1.0 References: <20240421180122.1650812-1-michael.roth@amd.com> <20240421180122.1650812-22-michael.roth@amd.com> <20240426173515.6pio42iqvjj2aeac@amd.com> <20240426214633.myecxgh6ci3qshmi@amd.com> <20240427013210.ioz7mv3yuu2r5un6@amd.com> Message-ID: Subject: Re: [PATCH v14 21/22] crypto: ccp: Add the SNP_{PAUSE,RESUME}_ATTESTATION commands From: Sean Christopherson To: Michael Roth Cc: kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com, ardb@kernel.org, pbonzini@redhat.com, vkuznets@redhat.com, jmattson@google.com, luto@kernel.org, dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com, peterz@infradead.org, srinivas.pandruvada@linux.intel.com, rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com, bp@alien8.de, vbabka@suse.cz, kirill@shutemov.name, ak@linux.intel.com, tony.luck@intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com, jarkko@kernel.org, ashish.kalra@amd.com, nikunj.dadhania@amd.com, pankaj.gupta@amd.com, liam.merwick@oracle.com, Larry.Dewey@amd.com Content-Type: text/plain; charset="us-ascii" X-Rspam-User: X-Stat-Signature: 6xj9wwt1jr38n3apcs39ihknb9a7uxa5 X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 536B5160037 X-HE-Tag: 1714400845-235652 X-HE-Meta: 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 xydwD6q/ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000039, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Apr 26, 2024, Michael Roth wrote: > On Fri, Apr 26, 2024 at 05:10:10PM -0700, Sean Christopherson wrote: > > e.g. put the cert in a directory along with a lock. Actually, IIUC, there doesn't > > even need to be a separate lock file. I know very little about userspace programming, > > but common sense and a quick search tells me that file locks are a solved problem. > > > > E.g. it took me ~5 minutes of Googling to come up with this, which AFAICT does > > exactly what you want. > > > > touch ~/vlek.cert > > ( > > flock -e 200 > > echo "Locked the cert, sleeping for 10 seconds" > > sleep 10 > > echo "Igor, it's alive!!!!!!" > > ) 200< vlek.cert > > > > touch ~/vlek.cert > > ( > > flock -s 201 > > echo "Got me a shared lock, no updates for you!" > > ) 201< vlek.cert > > > > Hmm... I did completely miss this option. But I think there are still some > issues here. IIUC you're suggesting (for example): > > "Management": > a) writelock vlek.cert > b) perform SNP_LOAD_VLEK and update vlek.cert contents > c) unlock vlek.cert > > "QEMU": > a) readlock vlek.cert > b) copy cert into guest buffer > c) unlock vlek.cert > > The issue is that after "QEMU" unlocks and return the cert to KVM we'll > have: > > "KVM" > a) return from EXT_GUEST_REQ exit to userspace > b) issue the attestation report to firmware > c) return the attestation report and cert to the guest > > Between a) and b), "Management" can complete another entire update, but > the cert that it passes back to the guest will be stale relative to the > key used to sign the attestation report. I was thinking userspace would hold the lock across SEV_CMD_SNP_GUEST_REQUEST. QEMU: a) readlock vlek.cert b) copy cert into guest buffer c) set kvm_run->immediate_exit d) invoke KVM_RUN e) KVM sends SEV_CMD_SNP_GUEST_REQUEST to PSP f) KVM exits to userspace with -EINTR g) unlock vlek.cert h) invoke KVM_RUN (resume the guest) > If we need to take more time to explore other options it's not > absolutely necessary to have the kernel solve this now. But every userspace > will need to solve it in some way so it seemed like it might be nice to > have a simple reference implementation to start with. Shoving something into the kernel is not a "reference implementation", especially not when it impacts the ABI of multiple subsystems.