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Commit 2cefc5fe authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Paolo Bonzini
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KVM: x86: hyperv: optimize kvm_hv_flush_tlb() for vp_index == vcpu_idx case 



VP inedx almost always matches VCPU and when it does it's faster to walk
the sparse set instead of all vcpus.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0b0a31ba

arch/x86/kvm/hyperv.c

+52 −44
Original line number Diff line number Diff line
@@ -1277,32 +1277,37 @@ int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host) 
		return kvm_hv_get_msr(vcpu, msr, pdata, host);

}



static __always_inline int get_sparse_bank_no(u64 valid_bank_mask, int bank_no)

static __always_inline bool hv_vcpu_in_sparse_set(struct kvm_vcpu_hv *hv_vcpu,

						  u64 sparse_banks[],

						  u64 valid_bank_mask)

{

	int i = 0, j;

	int bank = hv_vcpu->vp_index / 64, sbank;



	if (!(valid_bank_mask & BIT_ULL(bank_no)))

		return -1;

	if (bank >= 64)

		return false;



	for (j = 0; j < bank_no; j++)

		if (valid_bank_mask & BIT_ULL(j))

			i++;

	if (!(valid_bank_mask & BIT_ULL(bank)))

		return false;



	/* Sparse bank number equals to the number of set bits before it */

	sbank = bitmap_weight((unsigned long *)&valid_bank_mask, bank);



	return i;

	return !!(sparse_banks[sbank] & BIT_ULL(hv_vcpu->vp_index % 64));

}



static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,

			    u16 rep_cnt, bool ex)

{

	struct kvm *kvm = current_vcpu->kvm;

	struct kvm_vcpu_hv *hv_current = &current_vcpu->arch.hyperv;

	struct kvm_hv *hv = &kvm->arch.hyperv;

	struct kvm_vcpu_hv *hv_vcpu = &current_vcpu->arch.hyperv;

	struct hv_tlb_flush_ex flush_ex;

	struct hv_tlb_flush flush;

	struct kvm_vcpu *vcpu;

	unsigned long vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)] = {0};

	u64 valid_bank_mask = 0;

	u64 valid_bank_mask;

	u64 sparse_banks[64];

	int sparse_banks_len, i;

	int sparse_banks_len, i, bank, sbank;

	bool all_cpus;



	if (!ex) {
@@ -1312,6 +1317,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa, 
		trace_kvm_hv_flush_tlb(flush.processor_mask,

				       flush.address_space, flush.flags);



		valid_bank_mask = BIT_ULL(0);

		sparse_banks[0] = flush.processor_mask;

		all_cpus = flush.flags & HV_FLUSH_ALL_PROCESSORS;

	} else {
@@ -1344,52 +1350,54 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa, 
			return HV_STATUS_INVALID_HYPERCALL_INPUT;

	}



	cpumask_clear(&hv_current->tlb_lush);

	/*

	 * vcpu->arch.cr3 may not be up-to-date for running vCPUs so we can't

	 * analyze it here, flush TLB regardless of the specified address space.

	 */

	cpumask_clear(&hv_vcpu->tlb_lush);



	if (all_cpus) {

		kvm_make_vcpus_request_mask(kvm,

				    KVM_REQ_TLB_FLUSH | KVM_REQUEST_NO_WAKEUP,

				    NULL, &hv_current->tlb_lush);

				    NULL, &hv_vcpu->tlb_lush);

		goto ret_success;

	}



	if (atomic_read(&hv->num_mismatched_vp_indexes)) {

		kvm_for_each_vcpu(i, vcpu, kvm) {

		struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv;

		int bank = hv->vp_index / 64, sbank = 0;



		/* Banks >64 can't be represented */

		if (bank >= 64)

			continue;



		/* Non-ex hypercalls can only address first 64 vCPUs */

		if (!ex && bank)

			continue;

			if (hv_vcpu_in_sparse_set(&vcpu->arch.hyperv,

						  sparse_banks,

						  valid_bank_mask))

				__set_bit(i, vcpu_bitmap);

		}

		goto flush_request;

	}



		if (ex) {

	/*

			 * Check is the bank of this vCPU is in sparse

			 * set and get the sparse bank number.

	 * num_mismatched_vp_indexes is zero so every vcpu has

	 * vp_index == vcpu_idx.

	 */

			sbank = get_sparse_bank_no(valid_bank_mask, bank);

	sbank = 0;

	for_each_set_bit(bank, (unsigned long *)&valid_bank_mask,

			 BITS_PER_LONG) {

		for_each_set_bit(i,

				 (unsigned long *)&sparse_banks[sbank],

				 BITS_PER_LONG) {

			u32 vp_index = bank * 64 + i;



			/* A non-existent vCPU was specified */

			if (vp_index >= KVM_MAX_VCPUS)

				return HV_STATUS_INVALID_HYPERCALL_INPUT;



			if (sbank < 0)

				continue;

			__set_bit(vp_index, vcpu_bitmap);

		}



		if (!(sparse_banks[sbank] & BIT_ULL(hv->vp_index % 64)))

			continue;



		/*

		 * vcpu->arch.cr3 may not be up-to-date for running vCPUs so we

		 * can't analyze it here, flush TLB regardless of the specified

		 * address space.

		 */

		__set_bit(i, vcpu_bitmap);

		sbank++;

	}



flush_request:

	kvm_make_vcpus_request_mask(kvm,

				    KVM_REQ_TLB_FLUSH | KVM_REQUEST_NO_WAKEUP,

				    vcpu_bitmap, &hv_current->tlb_lush);

				    vcpu_bitmap, &hv_vcpu->tlb_lush);



ret_success:

	/* We always do full TLB flush, set rep_done = rep_cnt. */