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=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 EC046C4363A for ; Mon, 26 Oct 2020 18:27:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8FDFB2087C for ; Mon, 26 Oct 2020 18:27:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="D68MdNuX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1789728AbgJZS1S (ORCPT ); Mon, 26 Oct 2020 14:27:18 -0400 Received: from mail.skyhub.de ([5.9.137.197]:49482 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1784608AbgJZS1S (ORCPT ); Mon, 26 Oct 2020 14:27:18 -0400 Received: from zn.tnic (p200300ec2f07cc006122e8911baeacc6.dip0.t-ipconnect.de [IPv6:2003:ec:2f07:cc00:6122:e891:1bae:acc6]) (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 C30A51EC0269; Mon, 26 Oct 2020 19:27:16 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1603736836; 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=J7gB+xIiVP4/xXoJX7VDF5p2exgP9KcNKkar3A+uj5E=; b=D68MdNuX9FVQe7QzoiF0mlUCxpoCBaXh4LNRorj9TfVYqvP/3whRShOjrH0pIVTsniZAMt a219+d4JsOU4NBwSniPYxEghPuEYPderMUGvQ+UPQxSnrHb2Y4HchUGXfcgfRDkvvnWgWN D7HplpAhtMdk92Z2a50CaC/WfQDufUM= Date: Mon, 26 Oct 2020 19:27:06 +0100 From: Borislav Petkov To: Joerg Roedel Cc: x86@kernel.org, Joerg Roedel , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Kees Cook , Arvind Sankar , Martin Radev , Tom Lendacky , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/5] x86/boot/compressed/64: Introduce sev_status Message-ID: <20201026182706.GG22116@zn.tnic> References: <20201021123938.3696-1-joro@8bytes.org> <20201021123938.3696-2-joro@8bytes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201021123938.3696-2-joro@8bytes.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 21, 2020 at 02:39:34PM +0200, Joerg Roedel wrote: > From: Joerg Roedel > > Introduce sev_status and initialize it together with sme_me_mask to have > an indicator which SEV features are enabled. > > Signed-off-by: Joerg Roedel > --- > arch/x86/boot/compressed/mem_encrypt.S | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/boot/compressed/mem_encrypt.S b/arch/x86/boot/compressed/mem_encrypt.S > index dd07e7b41b11..2192b3bd78d8 100644 > --- a/arch/x86/boot/compressed/mem_encrypt.S > +++ b/arch/x86/boot/compressed/mem_encrypt.S > @@ -81,6 +81,13 @@ SYM_FUNC_START(set_sev_encryption_mask) > > bts %rax, sme_me_mask(%rip) /* Create the encryption mask */ > > + /* Read sev_status */ > + movl $MSR_AMD64_SEV, %ecx > + rdmsr > + shlq $32, %rdx > + orq %rdx, %rax > + movq %rax, sev_status(%rip) A couple of lines above you call get_sev_encryption_bit() which already reads MSR_AMD64_SEV. Why not set sev_status there too instead of reading that MSR again here? It can read that MSR once and use sev_status(%rip) from then on to avoid reading that MSR multiple times... -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette