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Commit b31c114b authored by Wanpeng Li's avatar Wanpeng Li Committed by Paolo Bonzini
Browse files

KVM: X86: Provide a capability to disable PAUSE intercepts 



Allow to disable pause loop exit/pause filtering on a per VM basis.

If some VMs have dedicated host CPUs, they won't be negatively affected
due to needlessly intercepted PAUSE instructions.

Thanks to Jan H. Schönherr's initial patch.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent caa057a2

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -813,6 +813,7 @@ struct kvm_arch { 


	bool mwait_in_guest;

	bool hlt_in_guest;

	bool pause_in_guest;



	bool ept_identity_pagetable_done;

	gpa_t ept_identity_map_addr;

arch/x86/kvm/svm.c

+2 −1
Original line number Diff line number Diff line
@@ -1460,7 +1460,8 @@ static void init_vmcb(struct vcpu_svm *svm) 
	svm->nested.vmcb = 0;

	svm->vcpu.arch.hflags = 0;



	if (boot_cpu_has(X86_FEATURE_PAUSEFILTER)) {

	if (boot_cpu_has(X86_FEATURE_PAUSEFILTER) &&

	    !kvm_pause_in_guest(svm->vcpu.kvm)) {

		control->pause_filter_count = 3000;

		set_intercept(svm, INTERCEPT_PAUSE);

	}

arch/x86/kvm/vmx.c

+13 −4
Original line number Diff line number Diff line
@@ -5595,7 +5595,7 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx) 
	}

	if (!enable_unrestricted_guest)

		exec_control &= ~SECONDARY_EXEC_UNRESTRICTED_GUEST;

	if (!ple_gap)

	if (kvm_pause_in_guest(vmx->vcpu.kvm))

		exec_control &= ~SECONDARY_EXEC_PAUSE_LOOP_EXITING;

	if (!kvm_vcpu_apicv_active(vcpu))

		exec_control &= ~(SECONDARY_EXEC_APIC_REGISTER_VIRT |
@@ -5758,7 +5758,7 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx) 
		vmcs_write64(POSTED_INTR_DESC_ADDR, __pa((&vmx->pi_desc)));

	}



	if (ple_gap) {

	if (!kvm_pause_in_guest(vmx->vcpu.kvm)) {

		vmcs_write32(PLE_GAP, ple_gap);

		vmx->ple_window = ple_window;

		vmx->ple_window_dirty = true;
@@ -7207,7 +7207,7 @@ static __exit void hardware_unsetup(void) 
 */

static int handle_pause(struct kvm_vcpu *vcpu)

{

	if (ple_gap)

	if (!kvm_pause_in_guest(vcpu->kvm))

		grow_ple_window(vcpu);



	/*
@@ -9903,6 +9903,13 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id) 
	return ERR_PTR(err);

}



static int vmx_vm_init(struct kvm *kvm)

{

	if (!ple_gap)

		kvm->arch.pause_in_guest = true;

	return 0;

}



static void __init vmx_check_processor_compat(void *rtn)

{

	struct vmcs_config vmcs_conf;
@@ -12052,7 +12059,7 @@ static void vmx_cancel_hv_timer(struct kvm_vcpu *vcpu) 


static void vmx_sched_in(struct kvm_vcpu *vcpu, int cpu)

{

	if (ple_gap)

	if (!kvm_pause_in_guest(vcpu->kvm))

		shrink_ple_window(vcpu);

}
@@ -12412,6 +12419,8 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = { 
	.cpu_has_accelerated_tpr = report_flexpriority,

	.cpu_has_high_real_mode_segbase = vmx_has_high_real_mode_segbase,



	.vm_init = vmx_vm_init,



	.vcpu_create = vmx_create_vcpu,

	.vcpu_free = vmx_free_vcpu,

	.vcpu_reset = vmx_vcpu_reset,

arch/x86/kvm/x86.c

+3 −1
Original line number Diff line number Diff line
@@ -2878,7 +2878,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) 
		r = KVM_CLOCK_TSC_STABLE;

		break;

	case KVM_CAP_X86_DISABLE_EXITS:

		r |=  KVM_X86_DISABLE_EXITS_HTL;

		r |=  KVM_X86_DISABLE_EXITS_HTL | KVM_X86_DISABLE_EXITS_PAUSE;

		if(kvm_can_mwait_in_guest())

			r |= KVM_X86_DISABLE_EXITS_MWAIT;

		break;
@@ -4235,6 +4235,8 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, 
			kvm->arch.mwait_in_guest = true;

		if (cap->args[0] & KVM_X86_DISABLE_EXITS_HTL)

			kvm->arch.hlt_in_guest = true;

		if (cap->args[0] & KVM_X86_DISABLE_EXITS_PAUSE)

			kvm->arch.pause_in_guest = true;

		r = 0;

		break;

	default:

arch/x86/kvm/x86.h

+8 −1
Original line number Diff line number Diff line
@@ -266,8 +266,10 @@ static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec) 


#define KVM_X86_DISABLE_EXITS_MWAIT          (1 << 0)

#define KVM_X86_DISABLE_EXITS_HTL            (1 << 1)

#define KVM_X86_DISABLE_EXITS_PAUSE          (1 << 2)

#define KVM_X86_DISABLE_VALID_EXITS          (KVM_X86_DISABLE_EXITS_MWAIT | \

                                              KVM_X86_DISABLE_EXITS_HTL)

                                              KVM_X86_DISABLE_EXITS_HTL | \

                                              KVM_X86_DISABLE_EXITS_PAUSE)



static inline bool kvm_mwait_in_guest(struct kvm *kvm)

{
@@ -279,4 +281,9 @@ static inline bool kvm_hlt_in_guest(struct kvm *kvm) 
	return kvm->arch.hlt_in_guest;

}



static inline bool kvm_pause_in_guest(struct kvm *kvm)

{

	return kvm->arch.pause_in_guest;

}



#endif