Commit 6398326b authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

KVM: PPC: Book3S HV P9: Stop using vc->dpdes 



The P9 path uses vc->dpdes only for msgsndp / SMT emulation. This adds
an ordering requirement between vcpu->doorbell_request and vc->dpdes for
no real benefit. Use vcpu->doorbell_request directly.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-53-npiggin@gmail.com
parent 617326ff

arch/powerpc/kvm/book3s_hv.c

+10 −8
Original line number Diff line number Diff line
@@ -761,6 +761,8 @@ static bool kvmppc_doorbell_pending(struct kvm_vcpu *vcpu) 


	if (vcpu->arch.doorbell_request)

		return true;

	if (cpu_has_feature(CPU_FTR_ARCH_300))

		return false;

	/*

	 * Ensure that the read of vcore->dpdes comes after the read

	 * of vcpu->doorbell_request.  This barrier matches the
@@ -2185,8 +2187,10 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64 id, 
		 * either vcore->dpdes or doorbell_request.

		 * On POWER8, doorbell_request is 0.

		 */

		*val = get_reg_val(id, vcpu->arch.vcore->dpdes |

				   vcpu->arch.doorbell_request);

		if (cpu_has_feature(CPU_FTR_ARCH_300))

			*val = get_reg_val(id, vcpu->arch.doorbell_request);

		else

			*val = get_reg_val(id, vcpu->arch.vcore->dpdes);

		break;

	case KVM_REG_PPC_VTB:

		*val = get_reg_val(id, vcpu->arch.vcore->vtb);
@@ -2423,6 +2427,9 @@ static int kvmppc_set_one_reg_hv(struct kvm_vcpu *vcpu, u64 id, 
		vcpu->arch.pspb = set_reg_val(id, *val);

		break;

	case KVM_REG_PPC_DPDES:

		if (cpu_has_feature(CPU_FTR_ARCH_300))

			vcpu->arch.doorbell_request = set_reg_val(id, *val) & 1;

		else

			vcpu->arch.vcore->dpdes = set_reg_val(id, *val);

		break;

	case KVM_REG_PPC_VTB:
@@ -4491,11 +4498,6 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit, 


	if (!nested) {

		kvmppc_core_prepare_to_enter(vcpu);

		if (vcpu->arch.doorbell_request) {

			vc->dpdes = 1;

			smp_wmb();

			vcpu->arch.doorbell_request = 0;

		}

		if (test_bit(BOOK3S_IRQPRIO_EXTERNAL,

			     &vcpu->arch.pending_exceptions))

			lpcr |= LPCR_MER;

arch/powerpc/kvm/book3s_hv_builtin.c

+2 −0
Original line number Diff line number Diff line
@@ -649,6 +649,8 @@ void kvmppc_guest_entry_inject_int(struct kvm_vcpu *vcpu) 
	int ext;

	unsigned long lpcr;



	WARN_ON_ONCE(cpu_has_feature(CPU_FTR_ARCH_300));



	/* Insert EXTERNAL bit into LPCR at the MER bit position */

	ext = (vcpu->arch.pending_exceptions >> BOOK3S_IRQPRIO_EXTERNAL) & 1;

	lpcr = mfspr(SPRN_LPCR);

arch/powerpc/kvm/book3s_hv_p9_entry.c

+10 −4
Original line number Diff line number Diff line
@@ -780,6 +780,7 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc 
	unsigned long host_pidr;

	unsigned long host_dawr1;

	unsigned long host_dawrx1;

	unsigned long dpdes;



	hdec = time_limit - *tb;

	if (hdec < 0)
@@ -842,8 +843,10 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc 


	if (vc->pcr)

		mtspr(SPRN_PCR, vc->pcr | PCR_MASK);

	if (vc->dpdes)

		mtspr(SPRN_DPDES, vc->dpdes);

	if (vcpu->arch.doorbell_request) {

		vcpu->arch.doorbell_request = 0;

		mtspr(SPRN_DPDES, 1);

	}



	if (dawr_enabled()) {

		if (vcpu->arch.dawr0 != host_dawr0)
@@ -1074,7 +1077,10 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc 
	vcpu->arch.shregs.sprg2 = mfspr(SPRN_SPRG2);

	vcpu->arch.shregs.sprg3 = mfspr(SPRN_SPRG3);



	vc->dpdes = mfspr(SPRN_DPDES);

	dpdes = mfspr(SPRN_DPDES);

	if (dpdes)

		vcpu->arch.doorbell_request = 1;



	vc->vtb = mfspr(SPRN_VTB);



	dec = mfspr(SPRN_DEC);
@@ -1136,7 +1142,7 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc 
		}

	}



	if (vc->dpdes)

	if (dpdes)

		mtspr(SPRN_DPDES, 0);

	if (vc->pcr)

		mtspr(SPRN_PCR, PCR_MASK);