linux-kernel - [PATCH v6 20/20] KVM: nVMX: Allow VMX FRED controls

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Message-ID: <20250821223630.984383-21-xin@zytor.com>
Date: Thu, 21 Aug 2025 15:36:29 -0700
From: "Xin Li (Intel)" <xin@...or.com>
To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-doc@...r.kernel.org
Cc: pbonzini@...hat.com, seanjc@...gle.com, corbet@....net, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, xin@...or.com, luto@...nel.org,
        peterz@...radead.org, andrew.cooper3@...rix.com, chao.gao@...el.com,
        hch@...radead.org
Subject: [PATCH v6 20/20] KVM: nVMX: Allow VMX FRED controls

From: Xin Li <xin3.li@...el.com>

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

Signed-off-by: Xin Li <xin3.li@...el.com>
Signed-off-by: Xin Li (Intel) <xin@...or.com>
Tested-by: Shan Kang <shan.kang@...el.com>
Tested-by: Xuelian Guo <xuelian.guo@...el.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 266115525b9e..0b266e95db60 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -7436,7 +7436,8 @@ 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;
 	}
 }
 
@@ -7452,7 +7453,7 @@ 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 ac76cb33f3de..99106750b1e3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7957,6 +7957,7 @@ 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
 }
-- 
2.50.1