diff mbox series

[v4,16/19] KVM: nVMX: Add support for the secondary VM exit controls

Message ID 20250328171205.2029296-17-xin@zytor.com (mailing list archive)
State New
Headers show
Series Enable FRED with KVM VMX | expand

Commit Message

Xin Li (Intel) March 28, 2025, 5:12 p.m. UTC 
From: Xin Li <xin3.li@intel.com>

Enable the secondary VM exit controls to prepare for nested FRED.

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>
---

Change in v3:
* Read secondary VM exit controls from vmcs_conf insteasd of the hardware
  MSR MSR_IA32_VMX_EXIT_CTLS2 to avoid advertising features to L1 that KVM
  itself doesn't support, e.g. because the expected entry+exit pairs aren't
  supported. (Sean Christopherson)
---
 Documentation/virt/kvm/x86/nested-vmx.rst |  1 +
 arch/x86/kvm/vmx/capabilities.h           |  1 +
 arch/x86/kvm/vmx/nested.c                 | 21 ++++++++++++++++++++-
 arch/x86/kvm/vmx/vmcs12.c                 |  1 +
 arch/x86/kvm/vmx/vmcs12.h                 |  2 ++
 arch/x86/kvm/x86.h                        |  2 +-
 6 files changed, 26 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/Documentation/virt/kvm/x86/nested-vmx.rst b/Documentation/virt/kvm/x86/nested-vmx.rst
index ac2095d41f02..e64ef231f310 100644
--- a/Documentation/virt/kvm/x86/nested-vmx.rst
+++ b/Documentation/virt/kvm/x86/nested-vmx.rst
@@ -217,6 +217,7 @@  struct shadow_vmcs is ever changed.
 		u16 host_fs_selector;
 		u16 host_gs_selector;
 		u16 host_tr_selector;
+		u64 secondary_vm_exit_controls;
 	};
 
 
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index b4f49a4690ca..d29be4e4124e 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -38,6 +38,7 @@  struct nested_vmx_msrs {
 	u32 pinbased_ctls_high;
 	u32 exit_ctls_low;
 	u32 exit_ctls_high;
+	u64 secondary_exit_ctls;
 	u32 entry_ctls_low;
 	u32 entry_ctls_high;
 	u32 misc_low;
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 5504d9e9fd32..8b0c5e5f1e98 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1457,6 +1457,7 @@  int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
 	case MSR_IA32_VMX_PINBASED_CTLS:
 	case MSR_IA32_VMX_PROCBASED_CTLS:
 	case MSR_IA32_VMX_EXIT_CTLS:
+	case MSR_IA32_VMX_EXIT_CTLS2:
 	case MSR_IA32_VMX_ENTRY_CTLS:
 		/*
 		 * The "non-true" VMX capability MSRs are generated from the
@@ -1535,6 +1536,9 @@  int vmx_get_vmx_msr(struct nested_vmx_msrs *msrs, u32 msr_index, u64 *pdata)
 		if (msr_index == MSR_IA32_VMX_EXIT_CTLS)
 			*pdata |= VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR;
 		break;
+	case MSR_IA32_VMX_EXIT_CTLS2:
+		*pdata = msrs->secondary_exit_ctls;
+		break;
 	case MSR_IA32_VMX_TRUE_ENTRY_CTLS:
 	case MSR_IA32_VMX_ENTRY_CTLS:
 		*pdata = vmx_control_msr(
@@ -2485,6 +2489,11 @@  static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs0
 		exec_control &= ~VM_EXIT_LOAD_IA32_EFER;
 	vm_exit_controls_set(vmx, exec_control);
 
+	if (exec_control & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS) {
+		exec_control = __secondary_vm_exit_controls_get(vmcs01);
+		secondary_vm_exit_controls_set(vmx, exec_control);
+	}
+
 	/*
 	 * Interrupt/Exception Fields
 	 */
@@ -7011,7 +7020,7 @@  static void nested_vmx_setup_exit_ctls(struct vmcs_config *vmcs_conf,
 		VM_EXIT_HOST_ADDR_SPACE_SIZE |
 #endif
 		VM_EXIT_LOAD_IA32_PAT | VM_EXIT_SAVE_IA32_PAT |
-		VM_EXIT_CLEAR_BNDCFGS;
+		VM_EXIT_CLEAR_BNDCFGS | VM_EXIT_ACTIVATE_SECONDARY_CONTROLS;
 	msrs->exit_ctls_high |=
 		VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR |
 		VM_EXIT_LOAD_IA32_EFER | VM_EXIT_SAVE_IA32_EFER |
@@ -7020,6 +7029,16 @@  static void nested_vmx_setup_exit_ctls(struct vmcs_config *vmcs_conf,
 
 	/* We support free control of debug control saving. */
 	msrs->exit_ctls_low &= ~VM_EXIT_SAVE_DEBUG_CONTROLS;
+
+	if (msrs->exit_ctls_high & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS) {
+		msrs->secondary_exit_ctls = vmcs_conf->vmexit_2nd_ctrl;
+		/*
+		 * As the secondary VM exit control is always loaded, do not
+		 * advertise any feature in it to nVMX until its nVMX support
+		 * is ready.
+		 */
+		msrs->secondary_exit_ctls &= 0;
+	}
 }
 
 static void nested_vmx_setup_entry_ctls(struct vmcs_config *vmcs_conf,
diff --git a/arch/x86/kvm/vmx/vmcs12.c b/arch/x86/kvm/vmx/vmcs12.c
index 106a72c923ca..9fac24fd5b4b 100644
--- a/arch/x86/kvm/vmx/vmcs12.c
+++ b/arch/x86/kvm/vmx/vmcs12.c
@@ -66,6 +66,7 @@  const unsigned short vmcs12_field_offsets[] = {
 	FIELD64(HOST_IA32_PAT, host_ia32_pat),
 	FIELD64(HOST_IA32_EFER, host_ia32_efer),
 	FIELD64(HOST_IA32_PERF_GLOBAL_CTRL, host_ia32_perf_global_ctrl),
+	FIELD64(SECONDARY_VM_EXIT_CONTROLS, secondary_vm_exit_controls),
 	FIELD(PIN_BASED_VM_EXEC_CONTROL, pin_based_vm_exec_control),
 	FIELD(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control),
 	FIELD(EXCEPTION_BITMAP, exception_bitmap),
diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h
index 56fd150a6f24..1fe3ed9108aa 100644
--- a/arch/x86/kvm/vmx/vmcs12.h
+++ b/arch/x86/kvm/vmx/vmcs12.h
@@ -185,6 +185,7 @@  struct __packed vmcs12 {
 	u16 host_gs_selector;
 	u16 host_tr_selector;
 	u16 guest_pml_index;
+	u64 secondary_vm_exit_controls;
 };
 
 /*
@@ -360,6 +361,7 @@  static inline void vmx_check_vmcs12_offsets(void)
 	CHECK_OFFSET(host_gs_selector, 992);
 	CHECK_OFFSET(host_tr_selector, 994);
 	CHECK_OFFSET(guest_pml_index, 996);
+	CHECK_OFFSET(secondary_vm_exit_controls, 998);
 }
 
 extern const unsigned short vmcs12_field_offsets[];
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 24661b2ad3ad..75e1a0eb504c 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -67,7 +67,7 @@  void kvm_spurious_fault(void);
  * associated feature that KVM supports for nested virtualization.
  */
 #define KVM_FIRST_EMULATED_VMX_MSR	MSR_IA32_VMX_BASIC
-#define KVM_LAST_EMULATED_VMX_MSR	MSR_IA32_VMX_VMFUNC
+#define KVM_LAST_EMULATED_VMX_MSR	MSR_IA32_VMX_EXIT_CTLS2
 
 #define KVM_DEFAULT_PLE_GAP		128
 #define KVM_VMX_DEFAULT_PLE_WINDOW	4096