KVM: x86: Use supported_xcr0 to detect MPX support

Query supported_xcr0 when checking for MPX support instead of invoking
->mpx_supported() and drop ->mpx_supported() as kvm_mpx_supported() was
its last user.  Rename vmx_mpx_supported() to cpu_has_vmx_mpx() to
better align with VMX/VMCS nomenclature.

Modify VMX's adjustment of xcr0 to call cpus_has_vmx_mpx() (renamed from
vmx_mpx_supported()) directly to avoid reading supported_xcr0 before
it's fully configured.

No functional change intended.
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
[Test that *all* bits are set. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -1177,7 +1177,7 @@ struct kvm_x86_ops {
 			       struct x86_exception *exception);
 	void (*handle_exit_irqoff)(struct kvm_vcpu *vcpu,
 		enum exit_fastpath_completion *exit_fastpath);
-	bool (*mpx_supported)(void);
+
 	bool (*xsaves_supported)(void);
 	bool (*umip_emulated)(void);
 	bool (*pt_supported)(void);

arch/x86/kvm/cpuid.c

@@ -47,8 +47,8 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted)
 
 bool kvm_mpx_supported(void)
 {
-	return ((host_xcr0 & (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR))
-		 && kvm_x86_ops->mpx_supported());
+	return (supported_xcr0 & (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR))
+		== (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR);
 }
 EXPORT_SYMBOL_GPL(kvm_mpx_supported);
 

arch/x86/kvm/svm.c

@@ -6081,11 +6081,6 @@ static bool svm_invpcid_supported(void)
 	return false;
 }
 
-static bool svm_mpx_supported(void)
-{
-	return false;
-}
-
 static bool svm_xsaves_supported(void)
 {
 	return boot_cpu_has(X86_FEATURE_XSAVES);
@@ -7469,7 +7464,6 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 
 	.rdtscp_supported = svm_rdtscp_supported,
 	.invpcid_supported = svm_invpcid_supported,
-	.mpx_supported = svm_mpx_supported,
 	.xsaves_supported = svm_xsaves_supported,
 	.umip_emulated = svm_umip_emulated,
 	.pt_supported = svm_pt_supported,

arch/x86/kvm/vmx/capabilities.h

@@ -101,7 +101,7 @@ static inline bool cpu_has_load_perf_global_ctrl(void)
 	       (vmcs_config.vmexit_ctrl & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL);
 }
 
-static inline bool vmx_mpx_supported(void)
+static inline bool cpu_has_vmx_mpx(void)
 {
 	return (vmcs_config.vmexit_ctrl & VM_EXIT_CLEAR_BNDCFGS) &&
 		(vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_BNDCFGS);

arch/x86/kvm/vmx/vmx.c

@@ -7660,7 +7660,7 @@ static __init int hardware_setup(void)
 		WARN_ONCE(host_bndcfgs, "KVM: BNDCFGS in host will be lost");
 	}
 
-	if (!kvm_mpx_supported())
+	if (!cpu_has_vmx_mpx())
 		supported_xcr0 &= ~(XFEATURE_MASK_BNDREGS |
 				    XFEATURE_MASK_BNDCSR);
 
@@ -7927,7 +7927,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
 
 	.check_intercept = vmx_check_intercept,
 	.handle_exit_irqoff = vmx_handle_exit_irqoff,
-	.mpx_supported = vmx_mpx_supported,
 	.xsaves_supported = vmx_xsaves_supported,
 	.umip_emulated = vmx_umip_emulated,
 	.pt_supported = vmx_pt_supported,