From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CC4E517579; Fri, 14 Mar 2025 15:04:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741964645; cv=none; b=fYhamcMhPBckL8vjP/TI+he0LkVbMhLyiR+AfmqTU+/4xjvhFVetptlqq2OjcSDl4yUr1/rRcMJTJ2XTyR+BG7zN10/rze7pRMv4fuzhxhLaTWujeBCpi/QaGbzZd0ua6dz0oJyasLGIcq+w31dN73uQm0+Hl+x/Vn98xbQFya4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741964645; c=relaxed/simple; bh=0e0DjIP+VKfjwdEYSIUIE2NE30oUUxw6WwNZHuvge3A=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=syEl3MIKOq+/Q2WCT5o526b/2IuwpaEQK6F5d0/1yaQiqpGjuK6Vhu7+ZQg9I3uctR1nM5zC8yCqMrh7RbVMDbLwiwkSmc78We9QEQ2jhiNnQByNliqqtUKscG644jYTHANYPO7DPnuYpBZUVOPsfEC9kZaxgsLSaiXMYJibihk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dlTMJ/LP; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dlTMJ/LP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ABAF5C4CEE3; Fri, 14 Mar 2025 15:04:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741964645; bh=0e0DjIP+VKfjwdEYSIUIE2NE30oUUxw6WwNZHuvge3A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dlTMJ/LPHUArLjczhP9hRtw8xbFoO9c5acZfol2Gs5Q7IXltfeD/Tn0j1jVh5f59X Q++N7OWjc+gPpKq+SbV58XPwYclvkrHXvQOjPX8DeUEBrZIjC9Tb1ARZTIROn/GkNk +nkVecMAI/+hcxiUHvwXgZVhOE5t/h+0FfELm16RRVwAJNSdualYRnedaztMR+IMvo Anbv41RgSZz7/YmQ2rzDDTVgkk60mfLS1piXGO7UenTWaLS8kknNVBlA5Fgk4KFEMA RCeH4jDmE+ZTgPaZYvGZdh5nPJkxRzPrkvL4tE/lE7wafzTO2juGQ/z+yudZSSkp1p xYxfIQ6f5dS1Q== Date: Fri, 14 Mar 2025 17:04:00 +0200 From: Jarkko Sakkinen To: Stefano Garzarella Cc: Peter Huewe , Tom Lendacky , Jason Gunthorpe , x86@kernel.org, linux-kernel@vger.kernel.org, Borislav Petkov , linux-integrity@vger.kernel.org, Dov Murik , Dionna Glaze , linux-coco@lists.linux.dev, James Bottomley , Claudio Carvalho , Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , Dave Hansen , Joerg Roedel Subject: Re: [PATCH v3 1/4] x86/sev: add SVSM vTPM probe/send_command functions Message-ID: References: <20250311094225.35129-1-sgarzare@redhat.com> <20250311094225.35129-2-sgarzare@redhat.com> <2of2zhxi2c735fgvjxug2bxjfpz2zk25adf3h2ps5byau3rj3k@pgbxmpbskezi> 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=us-ascii Content-Disposition: inline In-Reply-To: <2of2zhxi2c735fgvjxug2bxjfpz2zk25adf3h2ps5byau3rj3k@pgbxmpbskezi> On Wed, Mar 12, 2025 at 11:56:06AM +0100, Stefano Garzarella wrote: > On Tue, Mar 11, 2025 at 11:56:23AM +0200, Jarkko Sakkinen wrote: > > On Tue, Mar 11, 2025 at 10:42:22AM +0100, Stefano Garzarella wrote: > > > Add two new functions to probe and send commands to the SVSM vTPM. > > > They leverage the two calls defined by the AMD SVSM specification [1] > > > for the vTPM protocol: SVSM_VTPM_QUERY and SVSM_VTPM_CMD. > > > > > > Expose these functions to be used by other modules such as a tpm > > > driver. > > > > > > [1] "Secure VM Service Module for SEV-SNP Guests" > > > Publication # 58019 Revision: 1.00 > > > > > > Co-developed-by: James Bottomley > > > Signed-off-by: James Bottomley > > > Co-developed-by: Claudio Carvalho > > > Signed-off-by: Claudio Carvalho > > > Signed-off-by: Stefano Garzarella > > > --- > > > v3: > > > - removed link to the spec because those URLs are unstable [Borislav] > > > - squashed "x86/sev: add SVSM call macros for the vTPM protocol" patch > > > in this one [Borislav] > > > - slimmed down snp_svsm_vtpm_probe() [Borislav] > > > - removed features check and any print related [Tom] > > > --- > > > arch/x86/include/asm/sev.h | 7 +++++++ > > > arch/x86/coco/sev/core.c | 31 +++++++++++++++++++++++++++++++ > > > 2 files changed, 38 insertions(+) > > > > > > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > > > index ba7999f66abe..09471d058ce5 100644 > > > --- a/arch/x86/include/asm/sev.h > > > +++ b/arch/x86/include/asm/sev.h > > > @@ -384,6 +384,10 @@ struct svsm_call { > > > #define SVSM_ATTEST_SERVICES 0 > > > #define SVSM_ATTEST_SINGLE_SERVICE 1 > > > > > > +#define SVSM_VTPM_CALL(x) ((2ULL << 32) | (x)) > > > +#define SVSM_VTPM_QUERY 0 > > > +#define SVSM_VTPM_CMD 1 > > > + > > > #ifdef CONFIG_AMD_MEM_ENCRYPT > > > > > > extern u8 snp_vmpl; > > > @@ -481,6 +485,9 @@ void snp_msg_free(struct snp_msg_desc *mdesc); > > > int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, > > > struct snp_guest_request_ioctl *rio); > > > > > > +bool snp_svsm_vtpm_probe(void); > > > +int snp_svsm_vtpm_send_command(u8 *buffer); > > > + > > > void __init snp_secure_tsc_prepare(void); > > > void __init snp_secure_tsc_init(void); > > > > > > diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c > > > index 96c7bc698e6b..2166bdff88b7 100644 > > > --- a/arch/x86/coco/sev/core.c > > > +++ b/arch/x86/coco/sev/core.c > > > @@ -2628,6 +2628,37 @@ static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_dat > > > return ret; > > > } > > > > > > > Since this is an exported symbol, it'd be a good practice document > > snp_svsm_vtpm_probe(). > > Yes, you are right, since the others were not documented, I had not added > it, but I agree with you, I'll do in v4. > > > > > > +bool snp_svsm_vtpm_probe(void) > > > +{ > > > + struct svsm_call call = {}; > > > + > > > + /* The vTPM device is available only if a SVSM is present */ > > > + if (!snp_vmpl) > > > + return false; > > > + > > > + call.caa = svsm_get_caa(); > > > + call.rax = SVSM_VTPM_CALL(SVSM_VTPM_QUERY); > > > > I supposed CAA is some kind of shared memory area for host and VM? > > Not with the host, but with SVSM, which is the firmware running in the > guest, but at a higher privilege level (VMPL) than the kernel, where, for > example, the vTPM is emulated. > > BTW, yep it is a shared memory defined by the SVSM calling convention. > From AMD SVSM specification: > > 5 Calling Convention > > Each call to the SVSM conveys data through a combination of the > SVSM Calling Area (whose address was first configured through the > SVSM_CAA field of the secrets page) and registers. Use of the > Calling Area is necessary for the SVSM to detect the difference > between a call that was issued by the guest and a spurious > invocation by a poorly behaved host. Registers are used for all > other parameters. > The initially configured SVSM Calling Area is a page of memory that > lies outside the initial SVSM memory range and has not had its VMPL > permissions restricted in any way. The address is guaranteed to be > aligned to a 4 KB boundary, so the remainder of the page may be used > by the guest for memory-based parameter passing if desired. > The contents of the Calling Area are described in the following > table: > > Table 2: Calling Area > Byte Size Name Description > Offset > > 0x000 1 byte SVSM_CALL_PENDING Indicates whether a call has > been requested by the guest > (0=no call requested, 1=call > requested). > 0x001 1 byte SVSM_MEM_AVAILABLE Free memory is available to > be withdrawn. > 0x002 6 byte Reserved. The SVSM is not > required to verify that > these bytes are 0. > > > > > > + > > > + if (svsm_perform_call_protocol(&call)) > > > + return false; > > > + > > > + /* Check platform commands contains TPM_SEND_COMMAND - platform command 8 */ > > > + return (call.rcx_out & BIT_ULL(8)) == BIT_ULL(8); > > > +} > > > +EXPORT_SYMBOL_GPL(snp_svsm_vtpm_probe); > > > + > > > > Ditto. > > Ack. > > > > > > +int snp_svsm_vtpm_send_command(u8 *buffer) > > > +{ > > > + struct svsm_call call = {}; > > > + > > > + call.caa = svsm_get_caa(); > > > + call.rax = SVSM_VTPM_CALL(SVSM_VTPM_CMD); > > > + call.rcx = __pa(buffer); > > > + > > > + return svsm_perform_call_protocol(&call); > > > +} > > > +EXPORT_SYMBOL_GPL(snp_svsm_vtpm_send_command); > > > + > > > static struct platform_device sev_guest_device = { > > > .name = "sev-guest", > > > .id = -1, > > > -- > > > 2.48.1 > > > > > > > That said, these are rather self-documenting (i.e, nice and clean). > > Thanks for the review! Sure, don't worry about it! Let's just cycle this enough rounds that it fits well... > Stefano BR, Jarkko