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The sevguest driver was a first mover in the confidential computing
space. As a first mover that afforded some leeway to build the driver
without concern for common infrastructure.
Now that sevguest is no longer a singleton [1] the common operation of
building and transmitting attestation report blobs can / should be made
common. In this model the so called "TSM-provider" implementations can
share a common envelope ABI even if the contents of that envelope remain
vendor-specific. When / if the industry agrees on an attestation record
format, that definition can also fit in the same ABI. In the meantime
the kernel's maintenance burden is reduced and collaboration on the
commons is increased.
Convert sevguest to use CONFIG_TSM_REPORTS to retrieve the data that
the SNP_GET_EXT_REPORT ioctl produces. An example flow follows for
retrieving the report blob via the TSM interface utility,
assuming no nonce and VMPL==2:
report=/sys/kernel/config/tsm/report/report0
mkdir $report
echo 2 > $report/privlevel
dd if=/dev/urandom bs=64 count=1 > $report/inblob
hexdump -C $report/outblob # SNP report
hexdump -C $report/auxblob # cert_table
rmdir $report
Given that the platform implementation is free to return empty
certificate data if none is available it lets configfs-tsm be simplified
as it only needs to worry about wrapping SNP_GET_EXT_REPORT, and leave
SNP_GET_REPORT alone.
The old ioctls can be lazily deprecated, the main motivation of this
effort is to stop the proliferation of new ioctls, and to increase
cross-vendor collaboration.
Link: http://lore.kernel.org/r/64961c3baf8ce_142af829436@dwillia2-xfh.jf.intel.com.notmuch [1]
Cc: Borislav Petkov <bp@alien8.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Dionna Glaze <dionnaglaze@google.com>
Cc: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Tested-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Tested-by: Alexey Kardashevskiy <aik@amd.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
17 lines
541 B
Plaintext
17 lines
541 B
Plaintext
config SEV_GUEST
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tristate "AMD SEV Guest driver"
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default m
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depends on AMD_MEM_ENCRYPT
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select CRYPTO
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select CRYPTO_AEAD2
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select CRYPTO_GCM
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select TSM_REPORTS
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help
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SEV-SNP firmware provides the guest a mechanism to communicate with
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the PSP without risk from a malicious hypervisor who wishes to read,
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alter, drop or replay the messages sent. The driver provides
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userspace interface to communicate with the PSP to request the
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attestation report and more.
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If you choose 'M' here, this module will be called sev-guest.
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