From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7BAA010E9 for ; Tue, 24 Jan 2023 09:35:59 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id AA0B1219EC; Tue, 24 Jan 2023 09:35:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1674552951; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SdxtwLNdyMTKUQRBNrerz9hnYMIgu77jvAErM6JRTRs=; b=HY4L9BalZ8m1avcRoIGhKO1LC+utj9QV+gJXHRBVHEPUv1WRmB3oU2RUiwK3zXr/Ky2ZSG xvGwZ7PPrOCHwgEie90agPzzxzbbo3hiomPYUFL30LpbmubmREW04DXZrCueeTuP0S2QcS LkxZ8Wdu7/zXiTUdOpMvggSnvsUHLfM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1674552951; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SdxtwLNdyMTKUQRBNrerz9hnYMIgu77jvAErM6JRTRs=; b=DOXl760Yyrenu1RTCKyxlmaeuw3KzsBLNozqn39GXxK6qw87sZcW0AqoZpqxmsqkM9t6Ns wGmYV7KtNv8lTqDw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 86FA2139FB; Tue, 24 Jan 2023 09:35:51 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id aJpoH3emz2MIVwAAMHmgww (envelope-from ); Tue, 24 Jan 2023 09:35:51 +0000 Date: Tue, 24 Jan 2023 10:35:50 +0100 From: =?iso-8859-1?Q?J=F6rg_R=F6del?= To: Tom Lendacky Cc: "linux-coco@lists.linux.dev" , "amd-sev-snp@lists.suse.com" Subject: Re: SVSM Attestation and vTPM specification additions - v0.60 Message-ID: References: <09819cb3-1938-fe86-b948-28aaffbe584e@amd.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <09819cb3-1938-fe86-b948-28aaffbe584e@amd.com> Hi, On Tue, Jan 10, 2023 at 12:54:27PM -0600, Tom Lendacky wrote: > Attached is an updated draft version of the SVSM specification with added > support for an attestation protocol and a vTPM protocol as well as other > miscellaneous changes (all identified by change bar). Please take a look and > reply with any feedback you may have. Thanks for putting this together, Tom! I think the review comments which have been posted cover a good amount of improvements, but I'd like to propose another addition: It would be great if we have an equivalent to EBUSY in the return codes to the guest. Something like SVSM_ERR_BUSY or SVSM_ERR_AGAIN, which tells the guest that some resources needed to fulfill the request are currently in-use and that the guest should try again later. The reasoning here is that in a setup with multiple VCPUs one CPU does a call to the SVSM which can take some time to complete (e.g. asking vTPM to generate an RSA key) and then another VCPU comes along with a second request to the vTPM. In that case the SVSM would have to busy-wait until the other request is finished. I think it would be better to return to the guest in this situation and try again later. Thoughts? Regards, -- Jörg Rödel jroedel@suse.de SUSE Software Solutions Germany GmbH Frankenstraße 146 90461 Nürnberg Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman