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KVM: SEV: Add known supported SEV-SNP policy bits

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Add to the known supported SEV-SNP policy bits that don't require any
implementation support from KVM in order to successfully use them.

At this time, this includes:
  - CXL_ALLOW
  - MEM_AES_256_XTS
  - RAPL_DIS
  - CIPHERTEXT_HIDING_DRAM
  - PAGE_SWAP_DISABLE

Arguably, RAPL_DIS and CIPHERTEXT_HIDING_DRAM require KVM and the CCP
driver to enable these features in order for the setting of the policy
bits to be successfully handled. But, a guest owner may not wish their
guest to run on a system that doesn't provide support for those features,
so allowing the specification of these bits accomplishes that. Whether
or not the bit is supported by SEV firmware, a system that doesn't support
these features will either fail during the KVM validation of supported
policy bits before issuing the LAUNCH_START or fail during the
LAUNCH_START.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://patch.msgid.link/ec040de9864099cf592a97c201dc4cc110b2b0cf.1761593632.git.thomas.lendacky@amd.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Tom Lendacky
2025-10-27 14:33:52 -05:00
committed by Sean Christopherson
parent 7a61d61396
commit 275d6d1189
1 changed files with 16 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
arch/x86/kvm/svm/sev.c
View File

@@ -65,12 +65,22 @@ module_param_named(ciphertext_hiding_asids, nr_ciphertext_hiding_asids, uint, 04
#define AP_RESET_HOLD_NAE_EVENT 1
#define AP_RESET_HOLD_MSR_PROTO 2
#define KVM_SNP_POLICY_MASK_VALID (SNP_POLICY_MASK_API_MINOR | \
SNP_POLICY_MASK_API_MAJOR | \
SNP_POLICY_MASK_SMT | \
SNP_POLICY_MASK_RSVD_MBO | \
SNP_POLICY_MASK_DEBUG | \
SNP_POLICY_MASK_SINGLE_SOCKET)
/*
* SEV-SNP policy bits that can be supported by KVM. These include policy bits
* that have implementation support within KVM or policy bits that do not
* require implementation support within KVM to enforce the policy.
*/
#define KVM_SNP_POLICY_MASK_VALID (SNP_POLICY_MASK_API_MINOR | \
SNP_POLICY_MASK_API_MAJOR | \
SNP_POLICY_MASK_SMT | \
SNP_POLICY_MASK_RSVD_MBO | \
SNP_POLICY_MASK_DEBUG | \
SNP_POLICY_MASK_SINGLE_SOCKET | \
SNP_POLICY_MASK_CXL_ALLOW | \
SNP_POLICY_MASK_MEM_AES_256_XTS | \
SNP_POLICY_MASK_RAPL_DIS | \
SNP_POLICY_MASK_CIPHERTEXT_HIDING_DRAM | \
SNP_POLICY_MASK_PAGE_SWAP_DISABLE)
static u64 snp_supported_policy_bits __ro_after_init;