Messages in this thread | | | Date | Tue, 21 Jun 2022 14:58:51 +0200 | Subject | Re: [PATCH v7 10/39] KVM: x86: hyper-v: Don't use sparse_set_to_vcpu_mask() in kvm_hv_send_ipi() | From | Paolo Bonzini <> |
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On 6/13/22 15:38, Vitaly Kuznetsov wrote: > Get rid of on-stack allocation of vcpu_mask and optimize kvm_hv_send_ipi() > for a smaller number of vCPUs in the request. When Hyper-V TLB flush > is in use, HvSendSyntheticClusterIpi{,Ex} calls are not commonly used to > send IPIs to a large number of vCPUs (and are rarely used in general). > > Introduce hv_is_vp_in_sparse_set() to directly check if the specified > VP_ID is present in sparse vCPU set. > > Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> > --- > arch/x86/kvm/hyperv.c | 37 ++++++++++++++++++++++++++----------- > 1 file changed, 26 insertions(+), 11 deletions(-)
I'm a bit confused by this patch being in this series.
Just to be clear, PV IPI does *not* support the VP_ID, right? And since patch 12 only affects the sparse banks, the patch does not have any other dependency. Is this correct?
Paolo
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c > index f41153c71beb..269a5fcca31b 100644 > --- a/arch/x86/kvm/hyperv.c > +++ b/arch/x86/kvm/hyperv.c > @@ -1747,6 +1747,25 @@ static void sparse_set_to_vcpu_mask(struct kvm *kvm, u64 *sparse_banks, > } > } > > +static bool hv_is_vp_in_sparse_set(u32 vp_id, u64 valid_bank_mask, u64 sparse_banks[]) > +{ > + int bank, sbank = 0; > + > + if (!test_bit(vp_id / HV_VCPUS_PER_SPARSE_BANK, > + (unsigned long *)&valid_bank_mask)) > + return false; > + > + for_each_set_bit(bank, (unsigned long *)&valid_bank_mask, > + KVM_HV_MAX_SPARSE_VCPU_SET_BITS) { > + if (bank == vp_id / HV_VCPUS_PER_SPARSE_BANK) > + break; > + sbank++; > + } > + > + return test_bit(vp_id % HV_VCPUS_PER_SPARSE_BANK, > + (unsigned long *)&sparse_banks[sbank]); > +} > + > struct kvm_hv_hcall { > u64 param; > u64 ingpa; > @@ -2029,8 +2048,8 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) > ((u64)hc->rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET); > } > > -static void kvm_send_ipi_to_many(struct kvm *kvm, u32 vector, > - unsigned long *vcpu_bitmap) > +static void kvm_hv_send_ipi_to_many(struct kvm *kvm, u32 vector, > + u64 *sparse_banks, u64 valid_bank_mask) > { > struct kvm_lapic_irq irq = { > .delivery_mode = APIC_DM_FIXED, > @@ -2040,7 +2059,10 @@ static void kvm_send_ipi_to_many(struct kvm *kvm, u32 vector, > unsigned long i; > > kvm_for_each_vcpu(i, vcpu, kvm) { > - if (vcpu_bitmap && !test_bit(i, vcpu_bitmap)) > + if (sparse_banks && > + !hv_is_vp_in_sparse_set(kvm_hv_get_vpindex(vcpu), > + valid_bank_mask, > + sparse_banks)) > continue; > > /* We fail only when APIC is disabled */ > @@ -2053,7 +2075,6 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) > struct kvm *kvm = vcpu->kvm; > struct hv_send_ipi_ex send_ipi_ex; > struct hv_send_ipi send_ipi; > - DECLARE_BITMAP(vcpu_mask, KVM_MAX_VCPUS); > u64 valid_bank_mask; > u64 sparse_banks[KVM_HV_MAX_SPARSE_VCPU_SET_BITS]; > u32 vector; > @@ -2115,13 +2136,7 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) > if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR)) > return HV_STATUS_INVALID_HYPERCALL_INPUT; > > - if (all_cpus) { > - kvm_send_ipi_to_many(kvm, vector, NULL); > - } else { > - sparse_set_to_vcpu_mask(kvm, sparse_banks, valid_bank_mask, vcpu_mask); > - > - kvm_send_ipi_to_many(kvm, vector, vcpu_mask); > - } > + kvm_hv_send_ipi_to_many(kvm, vector, all_cpus ? NULL : sparse_banks, valid_bank_mask); > > ret_success: > return HV_STATUS_SUCCESS;
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