On Thu, 2022-04-14 at 15:19 +0200, Vitaly Kuznetsov wrote: > To make kvm_hv_flush_tlb() ready to handle L2 TLB flush requests, KVM needs > to allow for all 64 sparse vCPU banks regardless of KVM_MAX_VCPUs as L1 > may use vCPU overcommit for L2. To avoid growing on-stack allocation, make > 'sparse_banks' part of per-vCPU 'struct kvm_vcpu_hv' which is allocated > dynamically. > > Note: sparse_set_to_vcpu_mask() keeps using on-stack allocation as it > won't be used to handle L2 TLB flush requests. > > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > --- > arch/x86/include/asm/kvm_host.h | 3 +++ > arch/x86/kvm/hyperv.c | 6 ++++-- > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 058061621872..837c07e213de 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -619,6 +619,9 @@ struct kvm_vcpu_hv { > } cpuid_cache; > > struct kvm_vcpu_hv_tlb_flush_ring tlb_flush_ring[HV_NR_TLB_FLUSH_RINGS]; > + > + /* Preallocated buffer for handling hypercalls passing sparse vCPU set */ > + u64 sparse_banks[64]; > }; > > /* Xen HVM per vcpu emulation context */ > diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c > index 1cef2b8f7001..e9793d36acca 100644 > --- a/arch/x86/kvm/hyperv.c > +++ b/arch/x86/kvm/hyperv.c > @@ -1968,6 +1968,8 @@ void kvm_hv_vcpu_flush_tlb(struct kvm_vcpu *vcpu) > > static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) > { > + struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); > + u64 *sparse_banks = hv_vcpu->sparse_banks; > struct kvm *kvm = vcpu->kvm; > struct hv_tlb_flush_ex flush_ex; > struct hv_tlb_flush flush; > @@ -1982,7 +1984,6 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) > u64 __tlb_flush_entries[KVM_HV_TLB_FLUSH_RING_SIZE - 2]; > u64 *tlb_flush_entries; > u64 valid_bank_mask; > - u64 sparse_banks[KVM_HV_MAX_SPARSE_VCPU_SET_BITS]; > struct kvm_vcpu *v; > unsigned long i; > bool all_cpus; > @@ -2134,11 +2135,12 @@ static void kvm_hv_send_ipi_to_many(struct kvm *kvm, u32 vector, > > static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) > { > + struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); > + u64 *sparse_banks = hv_vcpu->sparse_banks; > struct kvm *kvm = vcpu->kvm; > struct hv_send_ipi_ex send_ipi_ex; > struct hv_send_ipi send_ipi; > unsigned long valid_bank_mask; > - u64 sparse_banks[KVM_HV_MAX_SPARSE_VCPU_SET_BITS]; > u32 vector; > bool all_cpus; > Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx> Best regards, Maxim Levitsky