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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 90E37C433B4 for ; Tue, 11 May 2021 09:23:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4C0016157F for ; Tue, 11 May 2021 09:23:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231265AbhEKJYS (ORCPT ); Tue, 11 May 2021 05:24:18 -0400 Received: from mail.skyhub.de ([5.9.137.197]:45216 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230126AbhEKJYR (ORCPT ); Tue, 11 May 2021 05:24:17 -0400 Received: from zn.tnic (p200300ec2f0ec70079cd82bef3234244.dip0.t-ipconnect.de [IPv6:2003:ec:2f0e:c700:79cd:82be:f323:4244]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 03AA81EC04DE; Tue, 11 May 2021 11:23:09 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1620724990; h=from:from: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; bh=2BFJfXAt4RasctGcG7XZvImeLDWYB+zm7FzMoySZHus=; b=Ww1QaJQl377xw7ZOtlWjvHoC8Dgd0+Snh9DpsXI7OhvodVQZktNpt0QVAVcZe4k8CVAsUN +AWstQUXWdbXbrueFkK0CdCKMm6efG7Z9dXFXWTEuFMbVw4q2/HPEldWGfXjt4CzpeLj2V 8ZMzByLEDYSDLwEKEFC5UX9VI5APT7s= Date: Tue, 11 May 2021 11:23:05 +0200 From: Borislav Petkov To: Brijesh Singh Cc: x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, tglx@linutronix.de, jroedel@suse.de, thomas.lendacky@amd.com, pbonzini@redhat.com, mingo@redhat.com, dave.hansen@intel.com, rientjes@google.com, seanjc@google.com, peterz@infradead.org, hpa@zytor.com, tony.luck@intel.com Subject: Re: [PATCH Part1 RFC v2 02/20] x86/sev: Save the negotiated GHCB version Message-ID: References: <20210430121616.2295-1-brijesh.singh@amd.com> <20210430121616.2295-3-brijesh.singh@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210430121616.2295-3-brijesh.singh@amd.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Apr 30, 2021 at 07:15:58AM -0500, Brijesh Singh wrote: > The SEV-ES guest calls the sev_es_negotiate_protocol() to negotiate the > GHCB protocol version before establishing the GHCB. Cache the negotiated > GHCB version so that it can be used later. > > Signed-off-by: Brijesh Singh > --- > arch/x86/include/asm/sev.h | 2 +- > arch/x86/kernel/sev-shared.c | 15 ++++++++++++--- > 2 files changed, 13 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index fa5cd05d3b5b..7ec91b1359df 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -12,7 +12,7 @@ > #include > #include > > -#define GHCB_PROTO_OUR 0x0001UL > +#define GHCB_PROTOCOL_MIN 1ULL > #define GHCB_PROTOCOL_MAX 1ULL > #define GHCB_DEFAULT_USAGE 0ULL > > diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c > index 6ec8b3bfd76e..48a47540b85f 100644 > --- a/arch/x86/kernel/sev-shared.c > +++ b/arch/x86/kernel/sev-shared.c > @@ -14,6 +14,13 @@ > #define has_cpuflag(f) boot_cpu_has(f) > #endif > > +/* > + * Since feature negotitation related variables are set early in the boot > + * process they must reside in the .data section so as not to be zeroed > + * out when the .bss section is later cleared. * * GHCB protocol version negotiated with the hypervisor. */ > +static u16 ghcb_version __section(".data") = 0; Did you not see this when running checkpatch.pl on your patch? ERROR: do not initialise statics to 0 #141: FILE: arch/x86/kernel/sev-shared.c:22: +static u16 ghcb_version __section(".data") = 0; > static bool __init sev_es_check_cpu_features(void) > { > if (!has_cpuflag(X86_FEATURE_RDRAND)) { > @@ -54,10 +61,12 @@ static bool sev_es_negotiate_protocol(void) > if (GHCB_MSR_INFO(val) != GHCB_MSR_SEV_INFO_RESP) > return false; > > - if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTO_OUR || > - GHCB_MSR_PROTO_MIN(val) > GHCB_PROTO_OUR) > + if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTOCOL_MIN || > + GHCB_MSR_PROTO_MIN(val) > GHCB_PROTOCOL_MAX) > return false; > > + ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX); How is that even supposed to work? GHCB_PROTOCOL_MAX is 1 so ghcb_version will be always 1 when you do min_t() on values one of which is 1. Maybe I'm missing something... -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette