[PATCH v8 21/21] KVM: nVMX: Allow VMX FRED controls

Xin Li (Intel)
2025-10-14T01:10:56Z

Allow nVMX FRED controls as nested FRED support is in place.

Signed-off-by: Xin Li <xin3.li@intel.com>
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Tested-by: Shan Kang <shan.kang@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
---

Change in v5:
* Add TB from Xuelian Guo.
---
arch/x86/kvm/vmx/nested.c | 5 +++--
arch/x86/kvm/vmx/vmx.c | 1 +
2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 0867c1f09999..c8edbe9c7e00 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -7443,7 +7443,8 @@ static void nested_vmx_setup_exit_ctls(struct vmcs_config *vmcs_conf,
* advertise any feature in it to nVMX until its nVMX support
* is ready.
*/
- msrs->secondary_exit_ctls &= 0;
+ msrs->secondary_exit_ctls &= SECONDARY_VM_EXIT_SAVE_IA32_FRED |
+ SECONDARY_VM_EXIT_LOAD_IA32_FRED;
}
}

@@ -7459,7 +7460,7 @@ static void nested_vmx_setup_entry_ctls(struct vmcs_config *vmcs_conf,
VM_ENTRY_IA32E_MODE |
#endif
VM_ENTRY_LOAD_IA32_PAT | VM_ENTRY_LOAD_BNDCFGS |
- VM_ENTRY_LOAD_CET_STATE;
+ VM_ENTRY_LOAD_CET_STATE | VM_ENTRY_LOAD_IA32_FRED;
msrs->entry_ctls_high |=
(VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR | VM_ENTRY_LOAD_IA32_EFER |
VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index b92fc81af5c4..c1a6547bc0aa 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7975,6 +7975,7 @@ static void nested_vmx_cr_fixed1_bits_update(struct kvm_vcpu *vcpu)

entry = kvm_find_cpuid_entry_index(vcpu, 0x7, 1);
cr4_fixed1_update(X86_CR4_LAM_SUP, eax, feature_bit(LAM));
+ cr4_fixed1_update(X86_CR4_FRED, eax, feature_bit(FRED));

#undef cr4_fixed1_update
}
--
2.51.0