Re: [PART1 RFC v3 02/12] KVM: x86: Introducing kvm_x86_ops VM init/uninit hooks

Paolo Bonzini
2016-03-18T10:11:19Z

On 18/03/2016 07:09, Suravee Suthikulpanit wrote:
> Adding function pointers in struct kvm_x86_ops for processor-specific
> layer to provide hooks for when KVM initialize and un-initialize VM.

This is not the only thing your patch is doing, and the "other" change
definitely needs a lot more explanation about why you did it and how you
audited the code to ensure that it is safe.

Paolo

> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> ---
> arch/x86/include/asm/kvm_host.h | 3 +++
> arch/x86/kvm/x86.c | 10 +++++++++-
> virt/kvm/kvm_main.c | 8 ++++----
> 3 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 44adbb8..4b0dd0f 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -828,6 +828,9 @@ struct kvm_x86_ops {
> bool (*cpu_has_high_real_mode_segbase)(void);
> void (*cpuid_update)(struct kvm_vcpu *vcpu);
>
> + int (*vm_init)(struct kvm *kvm);
> + void (*vm_uninit)(struct kvm *kvm);
> +
> /* Create, but do not attach this VCPU */
> struct kvm_vcpu *(*vcpu_create)(struct kvm *kvm, unsigned id);
> void (*vcpu_free)(struct kvm_vcpu *vcpu);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 429c3f5..4d2961d 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -7700,6 +7700,8 @@ void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu)
>
> int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> {
> + int ret = 0;
> +
> if (type)
> return -EINVAL;
>
> @@ -7724,7 +7726,10 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> INIT_DELAYED_WORK(&kvm->arch.kvmclock_update_work, kvmclock_update_fn);
> INIT_DELAYED_WORK(&kvm->arch.kvmclock_sync_work, kvmclock_sync_fn);
>
> - return 0;
> + if (kvm_x86_ops->vm_init)
> + ret = kvm_x86_ops->vm_init(kvm);
> +
> + return ret;
> }
>
> static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
> @@ -7751,6 +7756,9 @@ static void kvm_free_vcpus(struct kvm *kvm)
> kvm_for_each_vcpu(i, vcpu, kvm)
> kvm_arch_vcpu_free(vcpu);
>
> + if (kvm_x86_ops->vm_uninit)
> + kvm_x86_ops->vm_uninit(kvm);
> +
> mutex_lock(&kvm->lock);
> for (i = 0; i < atomic_read(&kvm->online_vcpus); i++)
> kvm->vcpus[i] = NULL;
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 1ca0258..5460325 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -536,10 +536,6 @@ static struct kvm *kvm_create_vm(unsigned long type)
> if (!kvm)
> return ERR_PTR(-ENOMEM);
>
> - r = kvm_arch_init_vm(kvm, type);
> - if (r)
> - goto out_err_no_disable;
> -
> r = hardware_enable_all();
> if (r)
> goto out_err_no_disable;
> @@ -578,6 +574,10 @@ static struct kvm *kvm_create_vm(unsigned long type)
> atomic_set(&kvm->users_count, 1);
> INIT_LIST_HEAD(&kvm->devices);
>
> + r = kvm_arch_init_vm(kvm, type);
> + if (r)
> + goto out_err;
> +
> r = kvm_init_mmu_notifier(kvm);
> if (r)
> goto out_err;
>