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authorJacky Li <jackyli@google.com>2022-08-16 19:32:08 +0000
committerHerbert Xu <herbert@gondor.apana.org.au>2022-08-26 18:50:07 +0800
commitd8da2da21fdb1f5964c11c00f0cc84fb0edf31d0 (patch)
treece92f6542ff1fa89c875eaa5462f6b97c5954ce7 /Documentation/virt
parentd5eb916d889f12f27275e2049b9c4df43b7cfa13 (diff)
crypto: ccp - Initialize PSP when reading psp data file failed
Currently the OS fails the PSP initialization when the file specified at 'init_ex_path' does not exist or has invalid content. However the SEV spec just requires users to allocate 32KB of 0xFF in the file, which can be taken care of by the OS easily. To improve the robustness during the PSP init, leverage the retry mechanism and continue the init process: Before the first INIT_EX call, if the content is invalid or missing, continue the process by feeding those contents into PSP instead of aborting. PSP will then override it with 32KB 0xFF and return SEV_RET_SECURE_DATA_INVALID status code. In the second INIT_EX call, this 32KB 0xFF content will then be fed and PSP will write the valid data to the file. In order to do this, sev_read_init_ex_file should only be called once for the first INIT_EX call. Calling it again for the second INIT_EX call will cause the invalid file content overwriting the valid 32KB 0xFF data provided by PSP in the first INIT_EX call. Co-developed-by: Peter Gonda <pgonda@google.com> Signed-off-by: Peter Gonda <pgonda@google.com> Signed-off-by: Jacky Li <jackyli@google.com> Reported-by: Alper Gun <alpergun@google.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'Documentation/virt')
-rw-r--r--Documentation/virt/kvm/x86/amd-memory-encryption.rst5
1 files changed, 2 insertions, 3 deletions
diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
index 2d307811978c..935aaeb97fe6 100644
--- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
@@ -89,9 +89,8 @@ context. In a typical workflow, this command should be the first command issued.
The firmware can be initialized either by using its own non-volatile storage or
the OS can manage the NV storage for the firmware using the module parameter
-``init_ex_path``. The file specified by ``init_ex_path`` must exist. To create
-a new NV storage file allocate the file with 32KB bytes of 0xFF as required by
-the SEV spec.
+``init_ex_path``. If the file specified by ``init_ex_path`` does not exist or
+is invalid, the OS will create or override the file with output from PSP.
Returns: 0 on success, -negative on error