Gunyah KVM backend [1] requires custom vCPU allocation to associate architecture-specific state with each virtual CPU. The generic KVM core currently allocates vCPUs directly using the kvm_vcpu_cache slab, which does not allow architecture code to intervene in the allocation process. Introduce two weakly-defined functions, kvm_arch_vcpu_alloc() and kvm_arch_vcpu_free(), which default to using kmem_cache_zalloc() and kmem_cache_free() respectively. Architectures can override these functions to implement custom vCPU allocation behavior. Replace all direct allocations and frees of vCPUs in kvm_main.c with calls to these helper functions to allow arch-specific substitution. This change is required to support architectures such as Gunyah that must allocate architecture-private state along with the vCPU. [1] https://github.com/quic/gunyah-hypervisor Signed-off-by: Karim Manaouil <karim.manaouil@xxxxxxxxxx> --- include/linux/kvm_host.h | 2 ++ virt/kvm/kvm_main.c | 16 +++++++++++++--- 2 files changed, 15 insertions(+), 3 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 1dedc421b3e3..3461346b37e0 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1581,6 +1581,8 @@ int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id); int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu); +struct kvm_vcpu *kvm_arch_vcpu_alloc(void); +void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu); #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER int kvm_arch_pm_notifier(struct kvm *kvm, unsigned long state); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 69782df3617f..dbb7ed95523f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -476,7 +476,7 @@ static void kvm_vcpu_destroy(struct kvm_vcpu *vcpu) put_pid(vcpu->pid); free_page((unsigned long)vcpu->run); - kmem_cache_free(kvm_vcpu_cache, vcpu); + kvm_arch_vcpu_free(vcpu); } void kvm_destroy_vcpus(struct kvm *kvm) @@ -4067,6 +4067,16 @@ static void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu) } #endif +struct kvm_vcpu __attribute__((weak)) *kvm_arch_vcpu_alloc(void) +{ + return kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL_ACCOUNT); +} + +void __attribute__((weak)) kvm_arch_vcpu_free(struct kvm_vcpu *vcpu) +{ + return kmem_cache_free(kvm_vcpu_cache, vcpu); +} + /* * Creates some virtual cpus. Good luck creating more than one. */ @@ -4103,7 +4113,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, unsigned long id) kvm->created_vcpus++; mutex_unlock(&kvm->lock); - vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL_ACCOUNT); + vcpu = kvm_arch_vcpu_alloc(); if (!vcpu) { r = -ENOMEM; goto vcpu_decrement; @@ -4182,7 +4192,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, unsigned long id) vcpu_free_run_page: free_page((unsigned long)vcpu->run); vcpu_free: - kmem_cache_free(kvm_vcpu_cache, vcpu); + kvm_arch_vcpu_free(vcpu); vcpu_decrement: mutex_lock(&kvm->lock); kvm->created_vcpus--; -- 2.39.5
