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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BAD69C433EF for ; Fri, 12 Nov 2021 16:55:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9827461073 for ; Fri, 12 Nov 2021 16:55:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235333AbhKLQ6U (ORCPT ); Fri, 12 Nov 2021 11:58:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235331AbhKLQ6T (ORCPT ); Fri, 12 Nov 2021 11:58:19 -0500 Received: from mail-lj1-x236.google.com (mail-lj1-x236.google.com [IPv6:2a00:1450:4864:20::236]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 131F5C061766 for ; Fri, 12 Nov 2021 08:55:28 -0800 (PST) Received: by mail-lj1-x236.google.com with SMTP id e9so19724882ljl.5 for ; Fri, 12 Nov 2021 08:55:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Hm2H8ZgFFHPAU4qfb3b/BSJd0XRMlWu5AvWuSmXvi28=; b=SinHaY3dhHRcOqPVkPd1IPujerUVPA0LjnDsPyKqW0X7an9+Eob1/CJNtehkiWSTKc J58P+Dhs2EclH2aJMZGk2jbnVaLnad4j14xAxpBQvS5q4Ipcehsx5Hm5RDPgGHxzTlkW mG/g0ajk+n9y/CQrka0xuXN1ovB2GLxNHdBSer/GS3b1vXiY6B2lX6tBnu7qGK07PMQY py5fRDgADEDK6m/Jke8jUD36MUQKdLy7okHHM7qN8RwZZMpeiw0xhnGQHVmKhqYsofaQ avFQ9L6vmAjPHIphLbei9WeQ6egJxY2faHPdZRa2jh2rQZjB8zc7FosAgbiGpcna1Uyt uznA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Hm2H8ZgFFHPAU4qfb3b/BSJd0XRMlWu5AvWuSmXvi28=; b=Ic+o261HJaT9aJlu29Gxl6bEjVn4eMOLZ3MDKrxdFbiAGbnsUf0IOiwl98Z7dQRNyF NGD9XodhmghA0MMxAyyiReIMULPkfdUCe8825MiNcsvtzNuh0RYEyaWDqbj2Ij/TAT2+ kGt01tvTEtpn0YP2PH0fRzpakO8XZDpxDdjHmu9lXNPUE+WiY1wAd80aI5GFJde5wm7f 59i7fbFqYejMbXCxFA3y61s9bdRw6/dHKOeEzQ1lsN9Yt9iHuKVOJB6TH0YLWiL3ezEz y1OaI7bO07MUK2VfC4I9BVgaLBOyG/m07hFzPbxyRwEvUind0U2fcRT5KvrlrL07oMJ2 /jnA== X-Gm-Message-State: AOAM5307llDll7/FQqkMFyu8/GeEkU0LevzjQqSWABwAAzgAzPe/wAfe wjUGvVB6U5hqlMBIJiwgFrGiALOhLx6igmBWr2Vtug== X-Google-Smtp-Source: ABdhPJx34NZhoDLJkZ1e9VSfWbKvbXQCN+8BLUffYvOT/TIacZTnYFaak9yXMUlymqwpzXsuC7Wt5b+aAH6/CSbPRI0= X-Received: by 2002:a2e:6e12:: with SMTP id j18mr14475941ljc.527.1636736126134; Fri, 12 Nov 2021 08:55:26 -0800 (PST) MIME-Version: 1.0 References: <20211102142331.3753798-1-pgonda@google.com> <20211102142331.3753798-5-pgonda@google.com> In-Reply-To: From: Peter Gonda Date: Fri, 12 Nov 2021 09:55:14 -0700 Message-ID: Subject: Re: [PATCH V3 4/4] crypto: ccp - Add SEV_INIT_EX support To: Brijesh Singh Cc: Sean Christopherson , Thomas.Lendacky@amd.com, David Rientjes , Marc Orr , Joerg Roedel , Herbert Xu , John Allen , "David S. Miller" , Paolo Bonzini , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Wed, Nov 10, 2021 at 8:32 AM Peter Gonda wrote: > > On Tue, Nov 9, 2021 at 3:20 PM Brijesh Singh wrote: > > > > > > > > On 11/9/21 2:46 PM, Peter Gonda wrote: > > > On Tue, Nov 9, 2021 at 1:26 PM Sean Christopherson wrote: > > >> > > >> On Tue, Nov 09, 2021, Peter Gonda wrote: > > >>> On Tue, Nov 9, 2021 at 10:21 AM Sean Christopherson wrote: > > >>>> There's no need for this to be a function pointer, and the duplicate code can be > > >>>> consolidated. > > >>>> > > >>>> static int sev_do_init_locked(int cmd, void *data, int *error) > > >>>> { > > >>>> if (sev_es_tmr) { > > >>>> /* > > >>>> * Do not include the encryption mask on the physical > > >>>> * address of the TMR (firmware should clear it anyway). > > >>>> */ > > >>>> data.flags |= SEV_INIT_FLAGS_SEV_ES; > > >>>> data.tmr_address = __pa(sev_es_tmr); > > >>>> data.tmr_len = SEV_ES_TMR_SIZE; > > >>>> } > > >>>> return __sev_do_cmd_locked(SEV_CMD_INIT, &data, error); > > >>>> } > > >>>> > > >>>> static int __sev_init_locked(int *error) > > >>>> { > > >>>> struct sev_data_init data; > > >>>> > > >>>> memset(&data, 0, sizeof(data)); > > >>>> return sev_do_init_locked(cmd, &data, error); > > >>>> } > > >>>> > > >>>> static int __sev_init_ex_locked(int *error) > > >>>> { > > >>>> struct sev_data_init_ex data; > > >>>> > > >>>> memset(&data, 0, sizeof(data)); > > >>>> data.length = sizeof(data); > > >>>> data.nv_address = __psp_pa(sev_init_ex_nv_address); > > >>>> data.nv_len = NV_LENGTH; > > >>>> return sev_do_init_locked(SEV_CMD_INIT_EX, &data, error); > > >>>> } > > >>> > > >>> I am missing how this removes the duplication of the retry code, > > >>> parameter checking, and other error checking code.. With what you have > > >>> typed out I would assume I still need to function pointer between > > >>> __sev_init_ex_locked and __sev_init_locked. Can you please elaborate > > >>> here? > > >> > > >> Hmm. Ah, I got distracted between the original thought, the realization that > > >> the two commands used different structs, and typing up the above. > > >> > > >>> Also is there some reason the function pointer is not acceptable? > > >> > > >> It's not unacceptable, it would just be nice to avoid, assuming the alternative > > >> is cleaner. But I don't think any alternative is cleaner, since as you pointed > > >> out the above is a half-baked thought. > > > > > > OK I'll leave as is. > > > > > >> > > >>>>> + rc = init_function(error); > > >>>>> if (rc && *error == SEV_RET_SECURE_DATA_INVALID) { > > >>>>> /* > > >>>>> * INIT command returned an integrity check failure > > >>>>> @@ -286,8 +423,8 @@ static int __sev_platform_init_locked(int *error) > > >>>>> * failed and persistent state has been erased. > > >>>>> * Retrying INIT command here should succeed. > > >>>>> */ > > >>>>> - dev_dbg(sev->dev, "SEV: retrying INIT command"); > > >>>>> - rc = __sev_do_cmd_locked(SEV_CMD_INIT, &data, error); > > >>>>> + dev_notice(sev->dev, "SEV: retrying INIT command"); > > >>>>> + rc = init_function(error); > > >>>> > > >>>> The above comment says "persistent state has been erased", but __sev_do_cmd_locked() > > >>>> only writes back to the file if a relevant command was successful, which means > > >>>> that rereading the userspace file in __sev_init_ex_locked() will retry INIT_EX > > >>>> with the same garbage data. > > >>> > > >>> Ack my mistake, that comment is stale. I will update it so its correct > > >>> for the INIT and INIT_EX flows. > > >>>> > > >>>> IMO, the behavior should be to read the file on load and then use the kernel buffer > > >>>> without ever reloading (unless this is built as a module and is unloaded and reloaded). > > >>>> The writeback then becomes opportunistic in the sense that if it fails for some reason, > > >>>> the kernel's internal state isn't blasted away. > > >>> > > >>> One issue here is that the file read can fail on load so we use the > > >>> late retry to guarantee we can read the file. > > >> > > >> But why continue loading if reading the file fails on load? > > >> > > >>> The other point seems like preference. Users may wish to shutdown the PSP FW, > > >>> load a new file, and INIT_EX again with that new data. Why should we preclude > > >>> them from that functionality? > > >> > > >> I don't think we should preclude that functionality, but it needs to be explicitly > > >> tied to a userspace action, e.g. either on module load or on writing the param to > > >> change the path. If the latter is allowed, then it needs to be denied if the PSP > > >> is initialized, otherwise the kernel will be in a non-coherent state and AFAICT > > >> userspace will have a heck of a time even understanding what state has been used > > >> to initialize the PSP. > > > > > > If this driver is builtin the filesystem will be unavailable during > > > __init. Using the existing retries already built into > > > sev_platform_init() also the file to be read once userspace is > > > running, meaning the file system is usable. As I tried to explain in > > > the commit message. We could remove the sev_platform_init call during > > > sev_pci_init since this only actually needs to be initialized when the > > > first command requiring it is issues (either reading some keys/certs > > > from the PSP or launching an SEV guest). Then userspace in both the > > > builtin and module usage would know running one of those commands > > > cause the file to be read for PSP usage. Tom any thoughts on this? > > > > > > > One thing to note is that if we do the INIT on the first command then > > the first guest launch will take a longer. The init command is not > > cheap (especially with the SNP, it may take a longer because it has to > > do all those RMP setup etc). IIRC, in my early SEV series in I was doing > > the INIT during the first command execution and based on the > > recommendation moved to do the init on probe. > > > > Should we add a module param to control whether to do INIT on probe or > > delay until the first command ? > > Thats a good point Brijesh. I've only been testing this with SEV and > ES so haven't noticed that long setup time. I like the idea of a > module parameter to decide when to INIT, that should satisfy Sean's > concern that the user doesn't know when the INIT_EX file would be read > and that there is extra retry code (duplicated between sev_pci_init > and all the PSP commands). I'll get started on that. I need a little guidance on how to proceed with this. Should I have the new module parameter 'psp_init_on_probe' just disable PSP init on module init if false. Or should it also disable PSP init during command flow if it's true? I was thinking I should just have 'psp_init_on_probe' default to true, and if false it stops the PSP init during sev_pci_init(). If I add the second change that seems like it changes the ABI. Thoughts? > > > > > -Brijesh