[PATCH v3] KVM: nVMX: Add support for rdtscp

[Jan Kiszka <jan.kiszka@web.de>]

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From: Jan Kiszka <jan.kiszka@siemens.com>

If the guest CPU is supposed to support rdtscp and the host has rdtscp
enabled in the secondary execution controls, we can also expose this
feature to L1. Just extend nested_vmx_exit_handled to properly route
EXIT_REASON_RDTSCP.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

Changes in v3:
 - avoid needlessly touching vmx->nested if nested is off

 arch/x86/include/uapi/asm/vmx.h | 1 +
 arch/x86/kvm/vmx.c              | 9 +++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h
index c5f1a1d..1fe9218 100644
--- a/arch/x86/include/uapi/asm/vmx.h
+++ b/arch/x86/include/uapi/asm/vmx.h
@@ -67,6 +67,7 @@
 #define EXIT_REASON_EPT_VIOLATION       48
 #define EXIT_REASON_EPT_MISCONFIG       49
 #define EXIT_REASON_INVEPT              50
+#define EXIT_REASON_RDTSCP              51
 #define EXIT_REASON_PREEMPTION_TIMER    52
 #define EXIT_REASON_INVVPID             53
 #define EXIT_REASON_WBINVD              54
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 50c675b..fdd9f8b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2467,6 +2467,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
 	vmx->nested.nested_vmx_secondary_ctls_low = 0;
 	vmx->nested.nested_vmx_secondary_ctls_high &=
 		SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
+		SECONDARY_EXEC_RDTSCP |
 		SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
 		SECONDARY_EXEC_APIC_REGISTER_VIRT |
 		SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
@@ -7510,7 +7511,7 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu)
 		return nested_cpu_has(vmcs12, CPU_BASED_INVLPG_EXITING);
 	case EXIT_REASON_RDPMC:
 		return nested_cpu_has(vmcs12, CPU_BASED_RDPMC_EXITING);
-	case EXIT_REASON_RDTSC:
+	case EXIT_REASON_RDTSC: case EXIT_REASON_RDTSCP:
 		return nested_cpu_has(vmcs12, CPU_BASED_RDTSC_EXITING);
 	case EXIT_REASON_VMCALL: case EXIT_REASON_VMCLEAR:
 	case EXIT_REASON_VMLAUNCH: case EXIT_REASON_VMPTRLD:
@@ -8517,6 +8518,9 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 						exec_control);
 			}
 		}
+		if (nested && !vmx->rdtscp_enabled)
+			vmx->nested.nested_vmx_secondary_ctls_high &=
+				~SECONDARY_EXEC_RDTSCP;
 	}
 
 	/* Exposing INVPCID only when PCID is exposed */
@@ -9146,8 +9150,9 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 			exec_control &= ~SECONDARY_EXEC_RDTSCP;
 		/* Take the following fields only from vmcs12 */
 		exec_control &= ~(SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
+				  SECONDARY_EXEC_RDTSCP |
 				  SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
-                                  SECONDARY_EXEC_APIC_REGISTER_VIRT);
+				  SECONDARY_EXEC_APIC_REGISTER_VIRT);
 		if (nested_cpu_has(vmcs12,
 				CPU_BASED_ACTIVATE_SECONDARY_CONTROLS))
 			exec_control |= vmcs12->secondary_vm_exec_control;
-- 
2.1.4


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