[PATCH 7.3.y 1/2] KVM: SVM: Add a vCPU-aware helper to get supported DEBUGCTL bits

[Sasha Levin <sashal@kernel.org>]

From: Shivansh Dhiman <shivansh.dhiman@amd.com>

[ Upstream commit cd0e6f4d7cec11be97fe6476309719b23ab5accb ]

Replace DEBUGCTL_RESERVED_BITS with a vCPU-aware helper that provides the
set of supported bits so that KVM can handle bits that are conditionally
supported based on the vCPU model, e.g. for features like Bus Lock Detect.

No functional change intended.

Signed-off-by: Shivansh Dhiman <shivansh.dhiman@amd.com>
Reviewed-by: Nikunj A Dadhania <nikunj@amd.com>
[sean: invert from reserved => supported, massage changelog]
Link: https://patch.msgid.link/20260930193634.3415089-12-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Stable-dep-of: 053621535f01 ("KVM: nSVM: Check validity of vmcs01 save area copied from SMRAM on RSM")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/svm/nested.c | 8 ++++----
 arch/x86/kvm/svm/svm.c    | 6 +++---
 arch/x86/kvm/svm/svm.h    | 7 +++++--
 3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 2aa87ae6b8f31..ae5688e5c7fb0 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -821,7 +821,7 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm)
 		 * svm_set_msr's definition of reserved bits.
 		 */
 		svm_copy_lbrs(&vmcb02->save, save);
-		vmcb02->save.dbgctl &= ~DEBUGCTL_RESERVED_BITS;
+		vmcb02->save.dbgctl &= svm_get_supported_debugctl(vcpu);
 	} else {
 		svm_copy_lbrs(&vmcb02->save, &vmcb01->save);
 	}
@@ -1203,7 +1203,7 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu)
 }
 
 /* Copy state save area fields which are handled by VMRUN */
-void svm_copy_vmrun_state(struct vmcb_save_area *to_save,
+void svm_copy_vmrun_state(struct kvm_vcpu *vcpu, struct vmcb_save_area *to_save,
 			  struct vmcb_save_area *from_save)
 {
 	to_save->es = from_save->es;
@@ -1230,7 +1230,7 @@ void svm_copy_vmrun_state(struct vmcb_save_area *to_save,
 
 	if (kvm_cpu_cap_has(X86_FEATURE_LBRV)) {
 		svm_copy_lbrs(to_save, from_save);
-		to_save->dbgctl &= ~DEBUGCTL_RESERVED_BITS;
+		to_save->dbgctl &= svm_get_supported_debugctl(vcpu);
 	}
 }
 
@@ -2070,7 +2070,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
 
 	svm->nested.vmcb12_gpa = kvm_state->hdr.svm.vmcb_pa;
 
-	svm_copy_vmrun_state(&svm->vmcb01.ptr->save, save);
+	svm_copy_vmrun_state(vcpu, &svm->vmcb01.ptr->save, save);
 	nested_copy_vmcb_control_to_cache(svm, ctl);
 
 	svm_switch_vmcb(svm, &svm->nested.vmcb02);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 13c44d6196513..bb8a14f21e3e5 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3169,7 +3169,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 			data &= ~DEBUGCTLMSR_BTF;
 		}
 
-		if (data & DEBUGCTL_RESERVED_BITS)
+		if (data & ~svm_get_supported_debugctl(vcpu))
 			return 1;
 
 		if (svm->vmcb->save.dbgctl == data)
@@ -5064,7 +5064,7 @@ static int svm_enter_smm(struct kvm_vcpu *vcpu, union kvm_smram *smram)
 
 	BUILD_BUG_ON(offsetof(struct vmcb, save) != 0x400);
 
-	svm_copy_vmrun_state(m_save.map.hva + 0x400, &svm->vmcb01.ptr->save);
+	svm_copy_vmrun_state(vcpu, m_save.map.hva + 0x400, &svm->vmcb01.ptr->save);
 	return 0;
 }
 
@@ -5104,7 +5104,7 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const union kvm_smram *smram)
 	 * used during SMM (see svm_enter_smm())
 	 */
 
-	svm_copy_vmrun_state(&svm->vmcb01.ptr->save, m_save.map.hva + 0x400);
+	svm_copy_vmrun_state(vcpu, &svm->vmcb01.ptr->save, m_save.map.hva + 0x400);
 
 	/*
 	 * Enter the nested guest now
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 29bde741874ad..2216988365593 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -786,7 +786,10 @@ BUILD_SVM_MSR_BITMAP_HELPERS(bool, test, test)
 BUILD_SVM_MSR_BITMAP_HELPERS(void, clear, __clear)
 BUILD_SVM_MSR_BITMAP_HELPERS(void, set, __set)
 
-#define DEBUGCTL_RESERVED_BITS (~DEBUGCTLMSR_LBR)
+static inline u64 svm_get_supported_debugctl(struct kvm_vcpu *vcpu)
+{
+	return DEBUGCTLMSR_LBR;
+}
 
 /* svm.c */
 extern bool dump_invalid_vmcb;
@@ -876,7 +879,7 @@ void svm_leave_nested(struct kvm_vcpu *vcpu);
 void svm_free_nested(struct vcpu_svm *svm);
 int svm_allocate_nested(struct vcpu_svm *svm);
 int nested_svm_vmrun(struct kvm_vcpu *vcpu);
-void svm_copy_vmrun_state(struct vmcb_save_area *to_save,
+void svm_copy_vmrun_state(struct kvm_vcpu *vcpu, struct vmcb_save_area *to_save,
 			  struct vmcb_save_area *from_save);
 void svm_copy_vmloadsave_state(struct vmcb *to_vmcb, struct vmcb *from_vmcb);
 void nested_svm_vmexit(struct vcpu_svm *svm);
-- 
2.53.0