[PATCH 1/2] KVM: SVM: Drop the module param to control SEV-ES DebugSwap

[Sean Christopherson <seanjc@google.com>]

Rip out the DebugSwap module param, as the sequence of events that led to
its inclusion was one big mistake, the param no longer serves any purpose.

Commit d1f85fbe836e ("KVM: SEV: Enable data breakpoints in SEV-ES") goofed
by not adding a way for the userspace VMM to control the feature.
Functionally, that was fine, but it broke attestation signatures because
SEV_FEATURES are included in the signature.

Commit 5abf6dceb066 ("SEV: disable SEV-ES DebugSwap by default") fixed that
issue, but the underlying flaw of userspace not having a way to control
SEV_FEATURES was still there.

That flaw was addressed by commit 4f5defae7089 ("KVM: SEV: introduce
KVM_SEV_INIT2 operation"), and so then 4dd5ecacb9a4 ("KVM: SEV: allow
SEV-ES DebugSwap again") re-enabled DebugSwap by default.

Now that the dust has settled, the module param doesn't serve any
meaningful purpose.

Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/svm/sev.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index f59c65abe3cf..9b92f0cccfe6 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -53,9 +53,6 @@ module_param_named(sev_es, sev_es_enabled, bool, 0444);
 static bool sev_snp_enabled = true;
 module_param_named(sev_snp, sev_snp_enabled, bool, 0444);
 
-/* enable/disable SEV-ES DebugSwap support */
-static bool sev_es_debug_swap_enabled = true;
-module_param_named(debug_swap, sev_es_debug_swap_enabled, bool, 0444);
 static u64 sev_supported_vmsa_features;
 
 static unsigned int nr_ciphertext_hiding_asids;
@@ -3150,12 +3147,10 @@ void __init sev_hardware_setup(void)
 	sev_es_enabled = sev_es_supported;
 	sev_snp_enabled = sev_snp_supported;
 
-	if (!sev_es_enabled || !cpu_feature_enabled(X86_FEATURE_DEBUG_SWAP) ||
-	    !cpu_feature_enabled(X86_FEATURE_NO_NESTED_DATA_BP))
-		sev_es_debug_swap_enabled = false;
-
 	sev_supported_vmsa_features = 0;
-	if (sev_es_debug_swap_enabled)
+
+	if (sev_es_enabled && cpu_feature_enabled(X86_FEATURE_DEBUG_SWAP) &&
+	    cpu_feature_enabled(X86_FEATURE_NO_NESTED_DATA_BP))
 		sev_supported_vmsa_features |= SVM_SEV_FEAT_DEBUG_SWAP;
 
 	if (sev_snp_enabled && tsc_khz && cpu_feature_enabled(X86_FEATURE_SNP_SECURE_TSC))
-- 
2.52.0.457.g6b5491de43-goog