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

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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: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-53-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2021-11-23 19:52:30 +10:00 committed by Michael Ellerman
parent 617326ff01
commit 6398326b9b
3 changed files with 22 additions and 12 deletions
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18
arch/powerpc/kvm/book3s_hv.c
View File

@ -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);
@ -2423,7 +2427,10 @@ 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:
vcpu->arch.vcore->dpdes = set_reg_val(id, *val);
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:
vcpu->arch.vcore->vtb = set_reg_val(id, *val);
@ -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;

2
arch/powerpc/kvm/book3s_hv_builtin.c
View File

@ -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);

14
arch/powerpc/kvm/book3s_hv_p9_entry.c
View File

@ -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 @@ tm_return_to_guest:
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 @@ tm_return_to_guest:
}
}
if (vc->dpdes)
if (dpdes)
mtspr(SPRN_DPDES, 0);
if (vc->pcr)
mtspr(SPRN_PCR, PCR_MASK);