| From 8750e72a79dda2f665ce17b62049f4d62130d991 Mon Sep 17 00:00:00 2001 |
| From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@redhat.com> |
| Date: Thu, 7 Nov 2019 07:53:42 -0500 |
| Subject: KVM: remember position in kvm->vcpus array |
| MIME-Version: 1.0 |
| Content-Type: text/plain; charset=UTF-8 |
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| |
| From: Radim Krčmář <rkrcmar@redhat.com> |
| |
| commit 8750e72a79dda2f665ce17b62049f4d62130d991 upstream. |
| |
| Fetching an index for any vcpu in kvm->vcpus array by traversing |
| the entire array everytime is costly. |
| This patch remembers the position of each vcpu in kvm->vcpus array |
| by storing it in vcpus_idx under kvm_vcpu structure. |
| |
| Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> |
| Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> |
| Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
| [borntraeger@de.ibm.com]: backport to 4.19 (also fits for 5.4) |
| Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> |
| Acked-by: Paolo Bonzini <pbonzini@redhat.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| include/linux/kvm_host.h | 11 +++-------- |
| virt/kvm/kvm_main.c | 5 +++-- |
| 2 files changed, 6 insertions(+), 10 deletions(-) |
| |
| --- a/include/linux/kvm_host.h |
| +++ b/include/linux/kvm_host.h |
| @@ -248,7 +248,8 @@ struct kvm_vcpu { |
| struct preempt_notifier preempt_notifier; |
| #endif |
| int cpu; |
| - int vcpu_id; |
| + int vcpu_id; /* id given by userspace at creation */ |
| + int vcpu_idx; /* index in kvm->vcpus array */ |
| int srcu_idx; |
| int mode; |
| u64 requests; |
| @@ -551,13 +552,7 @@ static inline struct kvm_vcpu *kvm_get_v |
| |
| static inline int kvm_vcpu_get_idx(struct kvm_vcpu *vcpu) |
| { |
| - struct kvm_vcpu *tmp; |
| - int idx; |
| - |
| - kvm_for_each_vcpu(idx, tmp, vcpu->kvm) |
| - if (tmp == vcpu) |
| - return idx; |
| - BUG(); |
| + return vcpu->vcpu_idx; |
| } |
| |
| #define kvm_for_each_memslot(memslot, slots) \ |
| --- a/virt/kvm/kvm_main.c |
| +++ b/virt/kvm/kvm_main.c |
| @@ -2751,7 +2751,8 @@ static int kvm_vm_ioctl_create_vcpu(stru |
| goto unlock_vcpu_destroy; |
| } |
| |
| - BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]); |
| + vcpu->vcpu_idx = atomic_read(&kvm->online_vcpus); |
| + BUG_ON(kvm->vcpus[vcpu->vcpu_idx]); |
| |
| /* Now it's all set up, let userspace reach it */ |
| kvm_get_kvm(kvm); |
| @@ -2761,7 +2762,7 @@ static int kvm_vm_ioctl_create_vcpu(stru |
| goto unlock_vcpu_destroy; |
| } |
| |
| - kvm->vcpus[atomic_read(&kvm->online_vcpus)] = vcpu; |
| + kvm->vcpus[vcpu->vcpu_idx] = vcpu; |
| |
| /* |
| * Pairs with smp_rmb() in kvm_get_vcpu. Write kvm->vcpus |
