diff options
| author |   Marc Zyngier <maz@kernel.org> | 2021-11-16 16:04:01 +0000 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2021-12-08 04:24:14 -0500 |
| commit | c5b077549136584618a66258f09d8d4b41e7409c (patch) | |
| tree | 6d8e307d3e7bb7ba976a12f3b235463e9253d31d /include | |
| parent | KVM: s390: Use kvm_get_vcpu() instead of open-coded access (diff) | |
| download | linux-dev-c5b077549136584618a66258f09d8d4b41e7409c.tar.xz linux-dev-c5b077549136584618a66258f09d8d4b41e7409c.zip | |
KVM: Convert the kvm->vcpus array to a xarray
At least on arm64 and x86, the vcpus array is pretty huge (up to
1024 entries on x86) and is mostly empty in the majority of the cases
(running 1k vcpu VMs is not that common).
This mean that we end-up with a 4kB block of unused memory in the
middle of the kvm structure.
Instead of wasting away this memory, let's use an xarray instead,
which gives us almost the same flexibility as a normal array, but
with a reduced memory usage with smaller VMs.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Message-Id: <20211116160403.4074052-6-maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/kvm_host.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index e2f9f8f67c58..2201dc07126a 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -29,6 +29,7 @@ #include <linux/refcount.h> #include <linux/nospec.h> #include <linux/notifier.h> +#include <linux/xarray.h> #include <asm/signal.h> #include <linux/kvm.h> @@ -552,7 +553,7 @@ struct kvm { struct mutex slots_arch_lock; struct mm_struct *mm; /* userspace tied to this vm */ struct kvm_memslots __rcu *memslots[KVM_ADDRESS_SPACE_NUM]; - struct kvm_vcpu *vcpus[KVM_MAX_VCPUS]; + struct xarray vcpu_array; /* Used to wait for completion of MMU notifiers. */ spinlock_t mn_invalidate_lock; @@ -701,7 +702,7 @@ static inline struct kvm_vcpu *kvm_get_vcpu(struct kvm *kvm, int i) /* Pairs with smp_wmb() in kvm_vm_ioctl_create_vcpu. */ smp_rmb(); - return kvm->vcpus[i]; + return xa_load(&kvm->vcpu_array, i); } #define kvm_for_each_vcpu(idx, vcpup, kvm) \ |