From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.alien8.de (mail.alien8.de [65.109.113.108]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BEBC3481B5 for ; Wed, 17 Apr 2024 20:40:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=65.109.113.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713386461; cv=none; b=LdGRskCWa+LLNnBpU3YKpwxbfsmwk7gTXqT0cnHB8GfEMA0StSMzXvVxH2DuJe5ClQG2aU4gZxinp/xWFerG6mDxSh+zwj877Ahme3IqFyXdSUFqU8JhP+bM2KVyAhyYf7ZBJBbC0qcQQDVFOkG4f0KOtSefU8SwuU65zANSFNI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713386461; c=relaxed/simple; bh=xgZogUj89WqzyBAwgAsuVQjVj5WTZ3i1Q7lV9smEZo4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=u+sIYtcU51xEtm2JgaBqDlAKnJN2kCrqZmVYXSXOxMDnKiwszR5FQWBkdUxJg7t0wg9l04kuCIGXdd46LzmMZRR754cWeSydOI5TP75WzJImkumNTBm3I7YxFghI6JRZidlFAEYjN8YavCW2U6aVaJPng5Q/eTnxajq/4Mw26g8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de; spf=pass smtp.mailfrom=alien8.de; arc=none smtp.client-ip=65.109.113.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alien8.de Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTP id 2342440E0177; Wed, 17 Apr 2024 20:40:57 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mail.alien8.de Received: from mail.alien8.de ([127.0.0.1]) by localhost (mail.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id oCVnpNi6NNcn; Wed, 17 Apr 2024 20:40:52 +0000 (UTC) Received: from zn.tnic (pd953020b.dip0.t-ipconnect.de [217.83.2.11]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 110B140E0187; Wed, 17 Apr 2024 20:40:36 +0000 (UTC) Date: Wed, 17 Apr 2024 22:40:30 +0200 From: Borislav Petkov To: Tom Lendacky Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-coco@lists.linux.dev, svsm-devel@coconut-svsm.dev, Thomas Gleixner , Ingo Molnar , Dave Hansen , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Dan Williams , Michael Roth , Ashish Kalra Subject: Re: [PATCH v3 03/14] x86/sev: Check for the presence of an SVSM in the SNP Secrets page Message-ID: <20240417204030.GIZiAzvuLG6qcFFMyT@fat_crate.local> References: 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=utf-8 Content-Disposition: inline In-Reply-To: On Mon, Mar 25, 2024 at 05:26:22PM -0500, Tom Lendacky wrote: > During early boot phases, check for the presence of an SVSM when running > as an SEV-SNP guest. > > An SVSM is present if the 64-bit value at offset 0x148 into the secrets > page is non-zero. If an SVSM is present, save the SVSM Calling Area > address (CAA), located at offset 0x150 into the secrets page, and set > the VMPL level of the guest, which should be non-zero, to indicate the > presence of an SVSM. Where are we pointing to the SVSM spec? This is in the 0th message https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/specifications/58019.pdf but pls add it to our documentation here: Documentation/arch/x86/amd-memory-encryption.rst > Signed-off-by: Tom Lendacky > --- > arch/x86/boot/compressed/sev.c | 35 ++++++++--------- > arch/x86/include/asm/sev-common.h | 4 ++ > arch/x86/include/asm/sev.h | 25 +++++++++++- > arch/x86/kernel/sev-shared.c | 64 +++++++++++++++++++++++++++++++ > arch/x86/kernel/sev.c | 16 ++++++++ > 5 files changed, 125 insertions(+), 19 deletions(-) > > diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c > index 49dc9661176d..fe61ff630c7e 100644 > --- a/arch/x86/boot/compressed/sev.c > +++ b/arch/x86/boot/compressed/sev.c > @@ -12,6 +12,7 @@ > */ > #include "misc.h" > > +#include > #include > #include > #include > @@ -29,6 +30,15 @@ > static struct ghcb boot_ghcb_page __aligned(PAGE_SIZE); > struct ghcb *boot_ghcb; > > +/* > + * SVSM related information: > + * When running under an SVSM, the VMPL that Linux is executing at must be > + * non-zero. The VMPL is therefore used to indicate the presence of an SVSM. > + */ > +static u8 vmpl __section(".data"); > +static u64 boot_svsm_caa_pa __section(".data"); > +static struct svsm_ca *boot_svsm_caa __section(".data"); Explain what those last 2 are in comments above it pls. > /* > * SNP_FEATURES_IMPL_REQ is the mask of SNP features that will need > * guest side implementation for proper functioning of the guest. If any > @@ -480,6 +472,13 @@ static bool early_snp_init(struct boot_params *bp) > */ > setup_cpuid_table(cc_info); > > + /* > + * Record the SVSM Calling Area address (CAA) if the guest is not Calling Area (CA) address > + * running at VMPL0. The CA will be used to communicate with the and then you can use "CA" here. > + * SVSM to perform the SVSM services. > + */ > + setup_svsm_ca(cc_info); > + > /* > * Pass run-time kernel a pointer to CC info via boot_params so EFI > * config table doesn't need to be searched again during early startup > diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h > index b463fcbd4b90..68a8cdf6fd6a 100644 > --- a/arch/x86/include/asm/sev-common.h > +++ b/arch/x86/include/asm/sev-common.h > @@ -159,6 +159,10 @@ struct snp_psc_desc { > #define GHCB_TERM_NOT_VMPL0 3 /* SNP guest is not running at VMPL-0 */ > #define GHCB_TERM_CPUID 4 /* CPUID-validation failure */ > #define GHCB_TERM_CPUID_HV 5 /* CPUID failure during hypervisor fallback */ > +#define GHCB_TERM_SECRETS_PAGE 6 /* Secrets page failure */ > +#define GHCB_TERM_NO_SVSM 7 /* SVSM is not advertised in the secrets page */ > +#define GHCB_TERM_SVSM_VMPL0 8 /* SVSM is present but has set VMPL to 0 */ > +#define GHCB_TERM_SVSM_CAA 9 /* SVSM is present but the CA is not page aligned */ "CAA" in the comment I guess. :) > +/* > + * Maintain the GPA of the SVSM Calling Area (CA) in order to utilize the SVSM > + * services needed when not running in VMPL0. > + */ > +static void __head setup_svsm_ca(const struct cc_blob_sev_info *cc_info) > +{ > + struct snp_secrets_page_layout *secrets_page; Why was that thing ever called "_layout" and not simply snp_secrets_page? Fix it? > + u64 caa; > + > + BUILD_BUG_ON(sizeof(*secrets_page) != PAGE_SIZE); Put it in the header under the struct definition I guess. > + /* > + * Use __pa() since this routine is running identity mapped when > + * called, both by the decompressor code and the early kernel code. > + */ > + if (running_at_vmpl0((void *)__pa(&boot_ghcb_page))) > + return; > + > + /* > + * Not running at VMPL0, ensure everything has been properly supplied > + * for running under an SVSM. > + */ > + if (!cc_info || !cc_info->secrets_phys || cc_info->secrets_len != PAGE_SIZE) > + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SECRETS_PAGE); > + > + secrets_page = (struct snp_secrets_page_layout *)cc_info->secrets_phys; > + if (!secrets_page->svsm_size) > + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_NO_SVSM); > + > + if (!secrets_page->svsm_guest_vmpl) > + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SVSM_VMPL0); > + > + vmpl = secrets_page->svsm_guest_vmpl; > + > + caa = secrets_page->svsm_caa; > + if (!PAGE_ALIGNED(caa)) > + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SVSM_CAA); > + > + /* > + * The CA is identity mapped when this routine is called, both by the > + * decompressor code and the early kernel code. > + */ > + boot_svsm_caa = (struct svsm_ca *)caa; > + boot_svsm_caa_pa = caa; > +} > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index b59b09c2f284..64799a04feb4 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -135,6 +135,15 @@ struct ghcb_state { > static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data); > static DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa); > > +/* > + * SVSM related information: > + * When running under an SVSM, the VMPL that Linux is executing at must be > + * non-zero. The VMPL is therefore used to indicate the presence of an SVSM. > + */ > +static u8 vmpl __ro_after_init; > +static struct svsm_ca *boot_svsm_caa __ro_after_init; > +static u64 boot_svsm_caa_pa __ro_after_init; Uff, duplication. Let's put them in sev-shared.c pls and avoid that. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette