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Subject[PATCH v5 3/5] KVM: x86: hyperv: use get_vcpu_by_vpidx() in kvm_hv_flush_tlb()
Date
VP_INDEX almost always matches VCPU id and get_vcpu_by_vpidx() is fast,
use it instead of traversing full vCPU list every time.

To support the change split off get_vcpu_idx_by_vpidx() from
get_vcpu_by_vpidx().

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
---
arch/x86/kvm/hyperv.c | 78 ++++++++++++++++++++-------------------------------
1 file changed, 31 insertions(+), 47 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index b45ce136be2f..d1a911132b59 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -127,20 +127,31 @@ static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint,
return 0;
}

-static struct kvm_vcpu *get_vcpu_by_vpidx(struct kvm *kvm, u32 vpidx)
+static u32 get_vcpu_idx_by_vpidx(struct kvm *kvm, u32 vpidx)
{
struct kvm_vcpu *vcpu = NULL;
int i;

if (vpidx >= KVM_MAX_VCPUS)
- return NULL;
+ return U32_MAX;

vcpu = kvm_get_vcpu(kvm, vpidx);
if (vcpu && vcpu_to_hv_vcpu(vcpu)->vp_index == vpidx)
- return vcpu;
+ return vpidx;
kvm_for_each_vcpu(i, vcpu, kvm)
if (vcpu_to_hv_vcpu(vcpu)->vp_index == vpidx)
- return vcpu;
+ return i;
+ return U32_MAX;
+}
+
+static __always_inline struct kvm_vcpu *get_vcpu_by_vpidx(struct kvm *kvm,
+ u32 vpidx)
+{
+ u32 vcpu_idx = get_vcpu_idx_by_vpidx(kvm, vpidx);
+
+ if (vcpu_idx < KVM_MAX_VCPUS)
+ return kvm_get_vcpu(kvm, vcpu_idx);
+
return NULL;
}

@@ -1257,20 +1268,6 @@ 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)
-{
- int i = 0, j;
-
- if (!(valid_bank_mask & BIT_ULL(bank_no)))
- return -1;
-
- for (j = 0; j < bank_no; j++)
- if (valid_bank_mask & BIT_ULL(j))
- i++;
-
- return i;
-}
-
static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
u16 rep_cnt, bool ex)
{
@@ -1278,11 +1275,10 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
struct kvm_vcpu_hv *hv_current = &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};
- unsigned long valid_bank_mask = 0;
+ unsigned long valid_bank_mask;
u64 sparse_banks[64];
- int sparse_banks_len, i;
+ int sparse_banks_len, bank, i;
bool all_cpus;

if (!ex) {
@@ -1292,6 +1288,7 @@ 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 {
@@ -1332,38 +1329,25 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
goto ret_success;
}

- kvm_for_each_vcpu(i, vcpu, kvm) {
- struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv;
- int bank = hv->vp_index / 64, sbank = 0;
+ for_each_set_bit(bank, (unsigned long *)&valid_bank_mask,
+ BITS_PER_LONG) {

- /* Banks >64 can't be represented */
- if (bank >= 64)
- continue;
+ for_each_set_bit(i, (unsigned long *)&sparse_banks[bank],
+ BITS_PER_LONG) {
+ u32 vp_index = bank * 64 + i;
+ u32 vcpu_idx = get_vcpu_idx_by_vpidx(kvm, vp_index);

- /* Non-ex hypercalls can only address first 64 vCPUs */
- if (!ex && bank)
- continue;
+ /* A non-existent vCPU was specified */
+ if (vcpu_idx >= KVM_MAX_VCPUS)
+ return HV_STATUS_INVALID_HYPERCALL_INPUT;

- if (ex) {
/*
- * Check is the bank of this vCPU is in sparse
- * set and get the sparse bank number.
+ * 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.
*/
- sbank = get_sparse_bank_no(valid_bank_mask, bank);
-
- if (sbank < 0)
- continue;
+ __set_bit(vcpu_idx, 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);
}

kvm_make_vcpus_request_mask(kvm,
--
2.14.4
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