Commit 7d5e88d3 authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Paolo Bonzini
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KVM: x86: hyper-v: Use preallocated buffer in 'struct kvm_vcpu_hv' instead of... 


KVM: x86: hyper-v: Use preallocated buffer in 'struct kvm_vcpu_hv' instead of on-stack 'sparse_banks'

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() can't currently be used to handle L2
requests as KVM does not keep L2 VM_ID -> L2 VCPU_ID -> L1 vCPU mappings,
i.e. its vp_bitmap array is still bounded by the number of L1 vCPUs and so
can remain an on-stack allocation.

Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-19-vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 53ca765a

arch/x86/include/asm/kvm_host.h

+3 −0
Original line number Diff line number Diff line
@@ -665,6 +665,9 @@ struct kvm_vcpu_hv { 
	} cpuid_cache;



	struct kvm_vcpu_hv_tlb_flush_fifo tlb_flush_fifo[HV_NR_TLB_FLUSH_FIFOS];



	/* Preallocated buffer for handling hypercalls passing sparse vCPU set */

	u64 sparse_banks[HV_MAX_SPARSE_VCPU_BANKS];

};



/* Xen HVM per vcpu emulation context */

arch/x86/kvm/hyperv.c

+4 −2
Original line number Diff line number Diff line
@@ -1906,6 +1906,8 @@ int 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;
@@ -1919,7 +1921,6 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) 
	u64 __tlb_flush_entries[KVM_HV_TLB_FLUSH_FIFO_SIZE - 1];

	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;
@@ -2083,11 +2084,12 @@ 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;

	u64 valid_bank_mask;

	u64 sparse_banks[KVM_HV_MAX_SPARSE_VCPU_SET_BITS];

	u32 vector;

	bool all_cpus;