From 9f4701e05faeec20350d9fc550e37ae8d2e08c88 Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Thu, 29 May 2025 16:17:59 -0500 Subject: [PATCH] KVM: SVM: Allow SNP guest policy disallow running with SMT enabled KVM currently returns -EINVAL when it attempts to create an SNP guest if the SMT guest policy bit is not set. However, there is no reason to check this, as there is no specific support in KVM that is required to support this. The SEV firmware will determine if SMT has been enabled or disabled in the BIOS and process the policy in the proper way: - SMT enabled in BIOS - Guest policy SMT == 0 ==> SNP_LAUNCH_START fails with POLICY_FAILURE - Guest policy SMT == 1 ==> SNP_LAUNCH_START succeeds - SMT disabled in BIOS - Guest policy SMT == 0 ==> SNP_LAUNCH_START succeeds - Guest policy SMT == 1 ==> SNP_LAUNCH_START succeeds Remove the check for the SMT policy bit from snp_launch_start() and allow the firmware to perform the proper checking. Signed-off-by: Tom Lendacky Link: https://lore.kernel.org/r/71043abdd9ef23b6f98fffa9c5c6045ac3a50187.1748553480.git.thomas.lendacky@amd.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/sev.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 459c3b791fd43..9a6dd285dfff0 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2131,8 +2131,7 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) return -EINVAL; /* Check for policy bits that must be set */ - if (!(params.policy & SNP_POLICY_MASK_RSVD_MBO) || - !(params.policy & SNP_POLICY_MASK_SMT)) + if (!(params.policy & SNP_POLICY_MASK_RSVD_MBO)) return -EINVAL; if (params.policy & SNP_POLICY_MASK_SINGLE_SOCKET) -- 2.47.2