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KVM: x86: hyper-v: Don't use sparse_set_to_vcpu_mask() in kvm_hv_send_ipi()

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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: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-17-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2022-11-01 15:53:54 +01:00 • committed by Paolo Bonzini
parent ca7372aca7
commit b6c2c22fa7
1 changed files with 31 additions and 11 deletions
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42
arch/x86/kvm/hyperv.c
View file

@ -1741,6 +1741,28 @@ 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 valid_bit_nr = vp_id / HV_VCPUS_PER_SPARSE_BANK;
unsigned long sbank;
if (!test_bit(valid_bit_nr, (unsigned long *)&valid_bank_mask))
return false;
/*
* The index into the sparse bank is the number of preceding bits in
* the valid mask. Optimize for VMs with <64 vCPUs by skipping the
* fancy math if there can't possibly be preceding bits.
*/
if (valid_bit_nr)
sbank = hweight64(valid_bank_mask & GENMASK_ULL(valid_bit_nr - 1, 0));
else
sbank = 0;
return test_bit(vp_id % HV_VCPUS_PER_SPARSE_BANK,
(unsigned long *)&sparse_banks[sbank]);
}
struct kvm_hv_hcall {
u64 param;
u64 ingpa;
@ -2035,8 +2057,8 @@ ret_success:
((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,
@ -2046,7 +2068,9 @@ 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 */
@ -2059,7 +2083,6 @@ 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;
@ -2121,13 +2144,10 @@ check_and_send_ipi:
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);
}
if (all_cpus)
kvm_hv_send_ipi_to_many(kvm, vector, NULL, 0);
else
kvm_hv_send_ipi_to_many(kvm, vector, sparse_banks, valid_bank_mask);
ret_success:
return HV_STATUS_SUCCESS;