The GHCB specification declares that the firmware error value for
a guest request will be stored in the lower 32 bits of EXIT_INFO_2. The
upper 32 bits are for the VMM's own error code. The fw_err argument to
snp_guest_issue_request() is thus a misnomer, and callers will need
access to all 64 bits.
The type of unsigned long also causes problems, since sw_exit_info2 is
u64 (unsigned long long) vs the argument's unsigned long*. Change this
type for issuing the guest request. Pass the ioctl command struct's error
field directly instead of in a local variable, since an incomplete guest
request may not set the error code, and uninitialized stack memory would
be written back to user space.
The firmware might not even be called, so bookend the call with the no
firmware call error and clear the error.
Since the "fw_err" field is really exitinfo2 split into the upper bits'
vmm error code and lower bits' firmware error code, convert the 64 bit
value to a union.
[ bp:
- Massage commit message
- adjust code
- Fix a build issue as
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202303070609.vX6wp2Af-lkp@intel.com
- print exitinfo2 in hex
Tom:
- Correct -EIO exit case. ]
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230214164638.1189804-5-dionnaglaze@google.com
Link: https://lore.kernel.org/r/20230307192449.24732-12-bp@alien8.de
The PSP can return a "firmware error" code of -1 in circumstances where
the PSP has not actually been called. To make this protocol unambiguous,
name the value SEV_RET_NO_FW_CALL.
[ bp: Massage a bit. ]
Signed-off-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20221207010210.2563293-2-dionnaglaze@google.com
TDX guest driver exposes IOCTL interfaces to service TDX guest
user-specific requests. Currently, it is only used to allow the user to
get the TDREPORT to support TDX attestation.
Details about the TDX attestation process are documented in
Documentation/x86/tdx.rst, and the IOCTL details are documented in
Documentation/virt/coco/tdx-guest.rst.
Operations like getting TDREPORT involves sending a blob of data as
input and getting another blob of data as output. It was considered
to use a sysfs interface for this, but it doesn't fit well into the
standard sysfs model for configuring values. It would be possible to
do read/write on files, but it would need multiple file descriptors,
which would be somewhat messy. IOCTLs seem to be the best fitting
and simplest model for this use case. The AMD sev-guest driver also
uses the IOCTL interface to support attestation.
[Bagas Sanjaya: Ack is for documentation portion]
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Wander Lairson Costa <wander@redhat.com>
Link: https://lore.kernel.org/all/20221116223820.819090-3-sathyanarayanan.kuppuswamy%40linux.intel.com
Update the documentation with information regarding SEV-SNP CPUID
Enforcement details and what sort of assurances it provides to guests.
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-47-brijesh.singh@amd.com
Version 2 of GHCB specification defines Non-Automatic-Exit (NAE) to get
extended guest report which is similar to the SNP_GET_REPORT ioctl. The
main difference is related to the additional data that will be returned.
That additional data returned is a certificate blob that can be used by
the SNP guest user. The certificate blob layout is defined in the GHCB
specification. The driver simply treats the blob as a opaque data and
copies it to userspace.
[ bp: Massage commit message, cast 1st arg of access_ok() ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-46-brijesh.singh@amd.com
The SNP_GET_DERIVED_KEY ioctl interface can be used by the SNP guest to
ask the firmware to provide a key derived from a root key. The derived
key may be used by the guest for any purposes it chooses, such as a
sealing key or communicating with the external entities.
See SEV-SNP firmware spec for more information.
[ bp: No need to memset "req" - it will get overwritten. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Link: https://lore.kernel.org/r/20220307213356.2797205-45-brijesh.singh@amd.com
The SEV-SNP specification provides the guest a mechanism to communicate
with the PSP without risk from a malicious hypervisor who wishes to
read, alter, drop or replay the messages sent. The driver uses
snp_issue_guest_request() to issue GHCB SNP_GUEST_REQUEST or
SNP_EXT_GUEST_REQUEST NAE events to submit the request to PSP.
The PSP requires that all communication should be encrypted using key
specified through a struct snp_guest_platform_data descriptor.
Userspace can use SNP_GET_REPORT ioctl() to query the guest attestation
report.
See SEV-SNP spec section Guest Messages for more details.
[ bp: Remove the "what" from the commit message, massage. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-44-brijesh.singh@amd.com
Dionna Glaze