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 X-Spam-Level: X-Spam-Status: No, score=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21C90C433DB for ; Tue, 2 Feb 2021 23:17:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CDF7764FC6 for ; Tue, 2 Feb 2021 23:17:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236442AbhBBXRK (ORCPT ); Tue, 2 Feb 2021 18:17:10 -0500 Received: from mail.kernel.org ([198.145.29.99]:49904 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236418AbhBBXRI (ORCPT ); Tue, 2 Feb 2021 18:17:08 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3921B64F74; Tue, 2 Feb 2021 23:16:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612307787; bh=vD9heg/ocCMzRX0Ub+/qDUdUBZRo012giLlKJyJKnX8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EFsyhma1Q5g+lrYAateEcRPIy/yd6gkRp0Q3ct3t053VBnCYKIVfDfka6MnDs3QX6 qVOPpSUOnfKCgXWqSJqVwnY0A8jaj6OHZSch0vD8LrQbab7vwd9zTElfoBqH+rqlZS N7msE4Jd4MWtdvhFGBktMfqSs4Hff5YMNDxBWndS7btcno+5cv0Cmq1WbHYfkwdJdf ULDHAOjFGTr22n9ofjymsP+9LHZ4PzoIYJ7f7HnxDjKjC2oKZpgCmtaURO4NZRsHF3 P4ps7K+utOgH4ftThUKMQ9gFfQ15gcEe89U4domHTArAaCGOKMl9V+3bRscSzPj9ao bMyY1aMo9WBOw== Date: Wed, 3 Feb 2021 01:16:20 +0200 From: Jarkko Sakkinen To: Sean Christopherson Cc: Kai Huang , linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org, luto@kernel.org, dave.hansen@intel.com, haitao.huang@intel.com, pbonzini@redhat.com, bp@alien8.de, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com Subject: Re: [RFC PATCH v3 08/27] x86/sgx: Initialize virtual EPC driver even when SGX driver is disabled Message-ID: References: <5076ed2c486ac33bfd87dc0e17047a1673692b53.1611634586.git.kai.huang@intel.com> <20210201184040.646ea9923c2119c205b3378d@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Feb 02, 2021 at 10:20:47AM -0800, Sean Christopherson wrote: > On Tue, Feb 02, 2021, Jarkko Sakkinen wrote: > > On Mon, Feb 01, 2021 at 06:40:40PM +1300, Kai Huang wrote: > > > On Sat, 30 Jan 2021 16:45:43 +0200 Jarkko Sakkinen wrote: > > > > On Tue, Jan 26, 2021 at 10:31:00PM +1300, Kai Huang wrote: > > > > > Modify sgx_init() to always try to initialize the virtual EPC driver, > > > > > even if the bare-metal SGX driver is disabled. The bare-metal driver > > > > > might be disabled if SGX Launch Control is in locked mode, or not > > > > > supported in the hardware at all. This allows (non-Linux) guests that > > > > > support non-LC configurations to use SGX. > > > > > > > > > > Signed-off-by: Kai Huang > > > > > --- > > > > > v2->v3: > > > > > > > > > > - Changed from sgx_virt_epc_init() to sgx_vepc_init(). > > > > > > > > > > --- > > > > > arch/x86/kernel/cpu/sgx/main.c | 4 +++- > > > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > > > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > > > > > index 21c2ffa13870..93d249f7bff3 100644 > > > > > --- a/arch/x86/kernel/cpu/sgx/main.c > > > > > +++ b/arch/x86/kernel/cpu/sgx/main.c > > > > > @@ -12,6 +12,7 @@ > > > > > #include "driver.h" > > > > > #include "encl.h" > > > > > #include "encls.h" > > > > > +#include "virt.h" > > > > > > > > > > struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS]; > > > > > static int sgx_nr_epc_sections; > > > > > @@ -712,7 +713,8 @@ static int __init sgx_init(void) > > > > > goto err_page_cache; > > > > > } > > > > > > > > > > - ret = sgx_drv_init(); > > > > > + /* Success if the native *or* virtual EPC driver initialized cleanly. */ > > > > > + ret = !!sgx_drv_init() & !!sgx_vepc_init(); > > > > > > > > If would create more dumb code and just add > > > > > > > > ret = sgx_vepc_init() > > > > if (ret) > > > > goto err_kthread; > > > > > > Do you mean you want below? > > > > > > ret = sgx_drv_init(); > > > ret = sgx_vepc_init(); > > > if (ret) > > > goto err_kthread; > > > > > > This was Sean's original code, but Dave didn't like it. > > > > I think it should be like: > > > > ret = sgx_drv_init(); > > if (ret) > > pr_warn("Driver initialization failed with %d\n", ret); > > > > ret = sgx_vepc_init(); > > if (ret) > > goto err_kthread; > > And that's wrong, it doesn't correctly handle the case where sgx_drv_init() > succeeds but sgx_vepc_init() fails. After reading all of this, I think that the only acceptable way to to manage this is to ret = sgx_drv_init(); if (ret && ret != -ENODEV) goto err_kthread; ret = sgx_vepc_init(); if (ret) goto err_kthread; Anything else would be a bad idea. We do support allowing KVM when the driver does not *support* SGX, not when something is working incorrectly. In that case it is a bad idea to allow any SGX related initialization to continue. Agreed that my earlier example is incorrect but so is the condition in the original patch. /Jarkko