[PATCH v8 01/21] KVM: VMX: Add support for the secondary VM exit controls

Xin Li (Intel)
2025-10-14T01:11:13Z

Always load the secondary VM exit controls to prepare for FRED enabling.

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

Change in v5:
* Add TB from Xuelian Guo.

Changes in v4:
* Fix clearing VM_EXIT_ACTIVATE_SECONDARY_CONTROLS (Chao Gao).
* Check VM exit/entry consistency based on the new macro from Sean
Christopherson.

Change in v3:
* Do FRED controls consistency checks in the VM exit/entry consistency
check framework (Sean Christopherson).

Change in v2:
* Always load the secondary VM exit controls (Sean Christopherson).
---
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/include/asm/vmx.h | 3 +++
arch/x86/kvm/vmx/capabilities.h | 9 ++++++++-
arch/x86/kvm/vmx/vmcs.h | 1 +
arch/x86/kvm/vmx/vmx.c | 29 +++++++++++++++++++++++++++--
arch/x86/kvm/vmx/vmx.h | 7 ++++++-
6 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 9e1720d73244..baf5e1648418 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -1225,6 +1225,7 @@
#define MSR_IA32_VMX_TRUE_ENTRY_CTLS 0x00000490
#define MSR_IA32_VMX_VMFUNC 0x00000491
#define MSR_IA32_VMX_PROCBASED_CTLS3 0x00000492
+#define MSR_IA32_VMX_EXIT_CTLS2 0x00000493

/* Resctrl MSRs: */
/* - Intel: */
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index c85c50019523..1f60c04d11fb 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -107,6 +107,7 @@
#define VM_EXIT_PT_CONCEAL_PIP 0x01000000
#define VM_EXIT_CLEAR_IA32_RTIT_CTL 0x02000000
#define VM_EXIT_LOAD_CET_STATE 0x10000000
+#define VM_EXIT_ACTIVATE_SECONDARY_CONTROLS 0x80000000

#define VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR 0x00036dff

@@ -262,6 +263,8 @@ enum vmcs_field {
SHARED_EPT_POINTER = 0x0000203C,
PID_POINTER_TABLE = 0x00002042,
PID_POINTER_TABLE_HIGH = 0x00002043,
+ SECONDARY_VM_EXIT_CONTROLS = 0x00002044,
+ SECONDARY_VM_EXIT_CONTROLS_HIGH = 0x00002045,
GUEST_PHYSICAL_ADDRESS = 0x00002400,
GUEST_PHYSICAL_ADDRESS_HIGH = 0x00002401,
VMCS_LINK_POINTER = 0x00002800,
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 02aadb9d730e..6bd67c40ca3b 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -55,8 +55,9 @@ struct vmcs_config {
u32 cpu_based_exec_ctrl;
u32 cpu_based_2nd_exec_ctrl;
u64 cpu_based_3rd_exec_ctrl;
- u32 vmexit_ctrl;
u32 vmentry_ctrl;
+ u32 vmexit_ctrl;
+ u64 vmexit_2nd_ctrl;
u64 misc;
struct nested_vmx_msrs nested;
};
@@ -141,6 +142,12 @@ static inline bool cpu_has_tertiary_exec_ctrls(void)
CPU_BASED_ACTIVATE_TERTIARY_CONTROLS;
}

+static inline bool cpu_has_secondary_vmexit_ctrls(void)
+{
+ return vmcs_config.vmexit_ctrl &
+ VM_EXIT_ACTIVATE_SECONDARY_CONTROLS;
+}
+
static inline bool cpu_has_vmx_virtualize_apic_accesses(void)
{
return vmcs_config.cpu_based_2nd_exec_ctrl &
diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h
index b25625314658..ae152a9d1963 100644
--- a/arch/x86/kvm/vmx/vmcs.h
+++ b/arch/x86/kvm/vmx/vmcs.h
@@ -47,6 +47,7 @@ struct vmcs_host_state {
struct vmcs_controls_shadow {
u32 vm_entry;
u32 vm_exit;
+ u64 secondary_vm_exit;
u32 pin;
u32 exec;
u32 secondary_exec;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f87c216d976d..255158595e77 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2595,8 +2595,9 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
u32 _cpu_based_exec_control = 0;
u32 _cpu_based_2nd_exec_control = 0;
u64 _cpu_based_3rd_exec_control = 0;
- u32 _vmexit_control = 0;
u32 _vmentry_control = 0;
+ u32 _vmexit_control = 0;
+ u64 _vmexit2_control = 0;
u64 basic_msr;
u64 misc_msr;

@@ -2617,6 +2618,12 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
{ VM_ENTRY_LOAD_CET_STATE, VM_EXIT_LOAD_CET_STATE },
};

+ struct {
+ u32 entry_control;
+ u64 exit_control;
+ } const vmcs_entry_exit2_pairs[] = {
+ };
+
memset(vmcs_conf, 0, sizeof(*vmcs_conf));

if (adjust_vmx_controls(KVM_REQUIRED_VMX_CPU_BASED_VM_EXEC_CONTROL,
@@ -2703,10 +2710,19 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
&_vmentry_control))
return -EIO;

+ if (_vmexit_control & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS)
+ _vmexit2_control =
+ adjust_vmx_controls64(KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS,
+ MSR_IA32_VMX_EXIT_CTLS2);
+
if (vmx_check_entry_exit_pairs(vmcs_entry_exit_pairs,
_vmentry_control, _vmexit_control))
return -EIO;

+ if (vmx_check_entry_exit_pairs(vmcs_entry_exit2_pairs,
+ _vmentry_control, _vmexit2_control))
+ return -EIO;
+
/*
* Some cpus support VM_{ENTRY,EXIT}_IA32_PERF_GLOBAL_CTRL but they
* can't be used due to an errata where VM Exit may incorrectly clear
@@ -2755,8 +2771,9 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
vmcs_conf->cpu_based_exec_ctrl = _cpu_based_exec_control;
vmcs_conf->cpu_based_2nd_exec_ctrl = _cpu_based_2nd_exec_control;
vmcs_conf->cpu_based_3rd_exec_ctrl = _cpu_based_3rd_exec_control;
- vmcs_conf->vmexit_ctrl = _vmexit_control;
vmcs_conf->vmentry_ctrl = _vmentry_control;
+ vmcs_conf->vmexit_ctrl = _vmexit_control;
+ vmcs_conf->vmexit_2nd_ctrl = _vmexit2_control;
vmcs_conf->misc = misc_msr;

#if IS_ENABLED(CONFIG_HYPERV)
@@ -4410,6 +4427,11 @@ static u32 vmx_get_initial_vmexit_ctrl(void)
~(VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL | VM_EXIT_LOAD_IA32_EFER);
}

+static u64 vmx_secondary_vmexit_ctrl(void)
+{
+ return vmcs_config.vmexit_2nd_ctrl;
+}
+
void vmx_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -4752,6 +4774,9 @@ static void init_vmcs(struct vcpu_vmx *vmx)

vm_exit_controls_set(vmx, vmx_get_initial_vmexit_ctrl());

+ if (cpu_has_secondary_vmexit_ctrls())
+ secondary_vm_exit_controls_set(vmx, vmx_secondary_vmexit_ctrl());
+
/* 22.2.1, 20.8.1 */
vm_entry_controls_set(vmx, vmx_get_initial_vmentry_ctrl());

diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index ea93121029f9..b2724aab48d2 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -511,7 +511,11 @@ static inline u8 vmx_get_rvi(void)
VM_EXIT_CLEAR_BNDCFGS | \
VM_EXIT_PT_CONCEAL_PIP | \
VM_EXIT_CLEAR_IA32_RTIT_CTL | \
- VM_EXIT_LOAD_CET_STATE)
+ VM_EXIT_LOAD_CET_STATE | \
+ VM_EXIT_ACTIVATE_SECONDARY_CONTROLS)
+
+#define KVM_REQUIRED_VMX_SECONDARY_VM_EXIT_CONTROLS (0)
+#define KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS (0)

#define KVM_REQUIRED_VMX_PIN_BASED_VM_EXEC_CONTROL \
(PIN_BASED_EXT_INTR_MASK | \
@@ -624,6 +628,7 @@ static __always_inline void lname##_controls_changebit(struct vcpu_vmx *vmx, u##
}
BUILD_CONTROLS_SHADOW(vm_entry, VM_ENTRY_CONTROLS, 32)
BUILD_CONTROLS_SHADOW(vm_exit, VM_EXIT_CONTROLS, 32)
+BUILD_CONTROLS_SHADOW(secondary_vm_exit, SECONDARY_VM_EXIT_CONTROLS, 64)
BUILD_CONTROLS_SHADOW(pin, PIN_BASED_VM_EXEC_CONTROL, 32)
BUILD_CONTROLS_SHADOW(exec, CPU_BASED_VM_EXEC_CONTROL, 32)
BUILD_CONTROLS_SHADOW(secondary_exec, SECONDARY_VM_EXEC_CONTROL, 32)
--
2.51.0