From: Dan Williams <dan.j.williams@intel.com>
To: Tom Lendacky <thomas.lendacky@amd.com>,
Dan Williams <dan.j.williams@intel.com>,
<linux-kernel@vger.kernel.org>, <x86@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
"Peter Zijlstra" <peterz@infradead.org>,
Michael Roth <michael.roth@amd.com>,
Ashish Kalra <ashish.kalra@amd.com>
Subject: Re: [PATCH 10/11] x86/sev: Extend the config-fs attestation support for an SVSM
Date: Fri, 23 Feb 2024 16:02:50 -0800 [thread overview]
Message-ID: <65d9322a53e90_2509b29456@dwillia2-mobl3.amr.corp.intel.com.notmuch> (raw)
In-Reply-To: <1adda7f0-0061-4296-ae6f-dd767676c23b@amd.com>
Tom Lendacky wrote:
> On 2/12/24 20:34, Dan Williams wrote:
> > Tom Lendacky wrote:
> >> On 2/2/24 01:10, Dan Williams wrote:
> >>> Tom Lendacky wrote:
> >>>> When an SVSM is present, the guest can also request attestation reports
> >>>> from the SVSM. These SVSM attestation reports can be used to attest the
> >>>> SVSM and any services running within the SVSM.
> >>>>
> >>>> Extend the config-fs attestation support to allow for an SVSM attestation
> >>>> report. This involves creating four (4) new config-fs attributes:
> >>>>
> >>>> - 'svsm' (input)
> >>>> This attribute is used to determine whether the attestation request
> >>>> should be sent to the SVSM or to the SEV firmware.
> >>>>
> >>>> - 'service_guid' (input)
> >>>> Used for requesting the attestation of a single service within the
> >>>> SVSM. A null GUID implies that the SVSM_ATTEST_SERVICES call should
> >>>> be used to request the attestation report. A non-null GUID implies
> >>>> that the SVSM_ATTEST_SINGLE_SERVICE call should be used.
> >>>>
> >>>> - 'service_version' (input)
> >>>> Used with the SVSM_ATTEST_SINGLE_SERVICE call, the service version
> >>>> represents a specific service manifest version be used for the
> >>>> attestation report.
> >>>>
> >>>> - 'manifestblob' (output)
> >>>> Used to return the service manifest associated with the attestation
> >>>> report.
> >>>>
> >>>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> >>>> ---
> >>>> Documentation/ABI/testing/configfs-tsm | 55 ++++++++++
> >>>> arch/x86/include/asm/sev.h | 31 +++++-
> >>>> arch/x86/kernel/sev.c | 50 +++++++++
> >>>> drivers/virt/coco/sev-guest/sev-guest.c | 137 ++++++++++++++++++++++++
> >>>> drivers/virt/coco/tsm.c | 95 +++++++++++++++-
> >>>> include/linux/tsm.h | 11 ++
> >>>> 6 files changed, 376 insertions(+), 3 deletions(-)
> >>>>
> >>>> diff --git a/Documentation/ABI/testing/configfs-tsm b/Documentation/ABI/testing/configfs-tsm
> >>>> index dd24202b5ba5..c5423987d323 100644
> >>>> --- a/Documentation/ABI/testing/configfs-tsm
> >>>> +++ b/Documentation/ABI/testing/configfs-tsm
> >>>> @@ -31,6 +31,21 @@ Description:
> >>>> Standardization v2.03 Section 4.1.8.1 MSG_REPORT_REQ.
> >>>> https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/specifications/56421.pdf
> >>>>
> >>>> +What: /sys/kernel/config/tsm/report/$name/manifestblob
> >>>> +Date: January, 2024
> >>>> +KernelVersion: v6.9
> >>>> +Contact: linux-coco@lists.linux.dev
> >>>> +Description:
> >>>> + (RO) Optional supplemental data that a TSM may emit, visibility
> >>>> + of this attribute depends on TSM, and may be empty if no
> >>>> + manifest data is available.
> >>>> +
> >>>> + When @provider is "sev_guest" and the "svsm" attribute is set
> >>>> + this file contains the service manifest used for the SVSM
> >>>> + attestation report from Secure VM Service Module for SEV-SNP
> >>>> + Guests v1.00 Section 7.
> >>>> + https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/specifications/58019.pdf
> >>>
> >>> I wish configfs had better dynamic visibility so that this could be
> >>> hidden when not active... oh well.
> >>
> >> So do I. I played with the idea of having two different structs and
> >> registering one or the other based on whether an SVSM was present. Thoughts?
> >
> > That's the status quo for the differences between TDX vs SEV
> > (tsm_report_default_type vs tsm_report_extra_type). I think a
> > "tsm_report_service_type " can be a new superset of
> > tsm_report_extra_type. That that just starts to get messy if
> > implementations start to pick and choose on a finer granularity what
> > they support. For example, what if TDX supports these new service
> > attributes, but not privlevel.
> >
> > It seems straightforward to add an is_visible() callback to
> > 'struct configfs_item_operations'. Then a common superset of all the
> > attributes could be specified, but with an is_visible() implementation
> > that consults with data registered with tsm_register() rather than the
> > @type argument directly.
>
> I've been playing with this a bit.
>
> For the configfs support I was thinking of doing a per attribute
> is_visible() callback field since the TSM support is currently all in one
> group. The callback field would be checked in fs/configfs/dir.c
> populate_attrs(). A simple bool return value should suffice, I'm not sure
> we need to get into umode changes. If the field is NULL, then the
> attribute is displayed. If non-NULL, it depends on the callback return value.
>
> In order to keep tsm.c as vendor neutral as possible, a way to
> provide/override a default callback would be needed. The new SVSM related
> fields would have a callback assigned that always returns false by
> default, so that these attributes wouldn't be visible. A new tsm.c
> interface that takes the attribute name and a callback function can be
> used to override the requested attribute. For example, the SEV guest
> driver could register a callback for these attributes that returns true
> when running under an SVSM or false otherwise. Or it could leave the
> default in place and register a callback when running under an SVSM that
> always returns true.
>
> Thoughts?
Sounds like a patch I want to see, yes. So the idea is the low-level
driver registers the is_visible() callback to the core and that gets to
filter attributes?
Hmm, as long as it ends up looking similar to sysfs is_visible()
prototype.
It could even just be a bitmask of attributes that gets passed in by the
provider, something like:
static struct configfs_attribute *tsm_report_attrs[] = {
[TSM_REPORT_ATTR_GENERATION] = &tsm_report_attr_generation,
[TSM_REPORT_ATTR_PROVIDER] = &tsm_report_attr_provider
[TSM_REPORT_ATTR_PRIVLEVEL] = &tsm_report_attr_privlevel,
[TSM_REPORT_ATTR_FLOOR] = &tsm_report_attr_privlevel_floor,
NULL,
};
bool tsm_report_is_visible(struct config_item *cfg, struct configfs_attribute *attr, int n)
{
return test_bit(n, &provider.attr_mask);
}
...and in is_bin_visible() for the binary attributes?
next prev parent reply other threads:[~2024-02-24 0:03 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-26 22:15 [PATCH 00/11] Provide SEV-SNP support for running under an SVSM Tom Lendacky
2024-01-26 22:15 ` [PATCH 01/11] x86/sev: Rename snp_init() in the boot/compressed/sev.c file Tom Lendacky
2024-01-27 0:05 ` Dionna Amalie Glaze
2024-01-27 14:38 ` Tom Lendacky
2024-01-26 22:15 ` [PATCH 02/11] x86/sev: Make the VMPL0 checking function more generic Tom Lendacky
2024-01-26 22:15 ` [PATCH 03/11] x86/sev: Check for the presence of an SVSM in the SNP Secrets page Tom Lendacky
2024-01-26 22:15 ` [PATCH 04/11] x86/sev: Use kernel provided SVSM Calling Areas Tom Lendacky
2024-01-27 0:45 ` Dionna Amalie Glaze
2024-01-27 14:43 ` Tom Lendacky
2024-01-26 22:15 ` [PATCH 05/11] x86/sev: Perform PVALIDATE using the SVSM when not at VMPL0 Tom Lendacky
2024-01-27 0:59 ` Dionna Amalie Glaze
2024-01-27 15:18 ` Tom Lendacky
2024-01-26 22:15 ` [PATCH 06/11] x86/sev: Use the SVSM to create a vCPU when not in VMPL0 Tom Lendacky
2024-01-26 22:16 ` [PATCH 07/11] x86/sev: Provide SVSM discovery support Tom Lendacky
2024-01-29 10:41 ` Jeremi Piotrowski
2024-01-29 15:18 ` Tom Lendacky
2024-01-26 22:16 ` [PATCH 08/11] x86/sev: Provide guest VMPL level to userspace Tom Lendacky
2024-01-27 1:06 ` Dionna Amalie Glaze
2024-01-27 15:43 ` Tom Lendacky
2024-01-26 22:16 ` [PATCH 09/11] virt: sev-guest: Choose the VMPCK key based on executing VMPL Tom Lendacky
2024-01-26 22:16 ` [PATCH 10/11] x86/sev: Extend the config-fs attestation support for an SVSM Tom Lendacky
2024-01-27 1:27 ` Dionna Amalie Glaze
2024-01-29 15:02 ` Tom Lendacky
2024-01-29 20:04 ` Dionna Amalie Glaze
2024-02-01 21:14 ` Tom Lendacky
2024-02-02 7:10 ` Dan Williams
2024-02-05 23:29 ` Kuppuswamy, Sathyanarayanan
2024-02-06 18:53 ` Tom Lendacky
2024-02-06 18:48 ` Tom Lendacky
2024-02-13 2:34 ` Dan Williams
2024-02-16 19:07 ` Tom Lendacky
2024-02-16 20:46 ` Dan Williams
2024-02-23 20:41 ` Tom Lendacky
2024-02-24 0:02 ` Dan Williams [this message]
2024-02-26 14:42 ` Tom Lendacky
2024-01-26 22:16 ` [PATCH 11/11] x86/sev: Allow non-VMPL0 execution when an SVSM is present Tom Lendacky
2024-02-12 10:40 ` [PATCH 00/11] Provide SEV-SNP support for running under an SVSM Reshetova, Elena
2024-02-16 19:46 ` Tom Lendacky
2024-02-19 16:57 ` Shutemov, Kirill
2024-02-19 17:54 ` Reshetova, Elena
2024-02-23 20:23 ` Tom Lendacky
2024-02-27 14:56 ` Reshetova, Elena
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