[PATCH v3 1/3] KVM: vmx: Enable VMFUNCs

From: Bandan Das
Date: Mon Jul 10 2017 - 15:54:28 EST


Enable VMFUNC in the secondary execution controls. This simplifies the
changes necessary to expose it to nested hypervisors. VMFUNCs still
cause #UD when invoked.

Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Bandan Das <bsd@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
---
arch/x86/include/asm/vmx.h | 3 +++
arch/x86/kvm/vmx.c | 22 +++++++++++++++++++++-
2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 35cd06f..da5375e 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -72,6 +72,7 @@
#define SECONDARY_EXEC_PAUSE_LOOP_EXITING 0x00000400
#define SECONDARY_EXEC_RDRAND 0x00000800
#define SECONDARY_EXEC_ENABLE_INVPCID 0x00001000
+#define SECONDARY_EXEC_ENABLE_VMFUNC 0x00002000
#define SECONDARY_EXEC_SHADOW_VMCS 0x00004000
#define SECONDARY_EXEC_RDSEED 0x00010000
#define SECONDARY_EXEC_ENABLE_PML 0x00020000
@@ -187,6 +188,8 @@ enum vmcs_field {
APIC_ACCESS_ADDR_HIGH = 0x00002015,
POSTED_INTR_DESC_ADDR = 0x00002016,
POSTED_INTR_DESC_ADDR_HIGH = 0x00002017,
+ VM_FUNCTION_CONTROL = 0x00002018,
+ VM_FUNCTION_CONTROL_HIGH = 0x00002019,
EPT_POINTER = 0x0000201a,
EPT_POINTER_HIGH = 0x0000201b,
EOI_EXIT_BITMAP0 = 0x0000201c,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ca5d2b9..a483b49 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1314,6 +1314,12 @@ static inline bool cpu_has_vmx_tsc_scaling(void)
SECONDARY_EXEC_TSC_SCALING;
}

+static inline bool cpu_has_vmx_vmfunc(void)
+{
+ return vmcs_config.cpu_based_2nd_exec_ctrl &
+ SECONDARY_EXEC_ENABLE_VMFUNC;
+}
+
static inline bool report_flexpriority(void)
{
return flexpriority_enabled;
@@ -3575,7 +3581,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
SECONDARY_EXEC_SHADOW_VMCS |
SECONDARY_EXEC_XSAVES |
SECONDARY_EXEC_ENABLE_PML |
- SECONDARY_EXEC_TSC_SCALING;
+ SECONDARY_EXEC_TSC_SCALING |
+ SECONDARY_EXEC_ENABLE_VMFUNC;
if (adjust_vmx_controls(min2, opt2,
MSR_IA32_VMX_PROCBASED_CTLS2,
&_cpu_based_2nd_exec_control) < 0)
@@ -5233,6 +5240,9 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
vmcs_writel(HOST_GS_BASE, 0); /* 22.2.4 */
#endif

+ if (cpu_has_vmx_vmfunc())
+ vmcs_write64(VM_FUNCTION_CONTROL, 0);
+
vmcs_write32(VM_EXIT_MSR_STORE_COUNT, 0);
vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, 0);
vmcs_write64(VM_EXIT_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.host));
@@ -7740,6 +7750,12 @@ static int handle_preemption_timer(struct kvm_vcpu *vcpu)
return 1;
}

+static int handle_vmfunc(struct kvm_vcpu *vcpu)
+{
+ kvm_queue_exception(vcpu, UD_VECTOR);
+ return 1;
+}
+
/*
* The exit handlers return 1 if the exit was handled fully and guest execution
* may resume. Otherwise they set the kvm_run parameter to indicate what needs
@@ -7790,6 +7806,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
[EXIT_REASON_XSAVES] = handle_xsaves,
[EXIT_REASON_XRSTORS] = handle_xrstors,
[EXIT_REASON_PML_FULL] = handle_pml_full,
+ [EXIT_REASON_VMFUNC] = handle_vmfunc,
[EXIT_REASON_PREEMPTION_TIMER] = handle_preemption_timer,
};

@@ -8111,6 +8128,9 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu)
case EXIT_REASON_PML_FULL:
/* We emulate PML support to L1. */
return false;
+ case EXIT_REASON_VMFUNC:
+ /* VM functions are emulated through L2->L0 vmexits. */
+ return false;
default:
return true;
}
--
2.9.4