Re: [PATCH v2 6/8] KVM: arm64: Add KVM_CAP_ARM_HW_DIRTY_LOG capability

[zhukeqian]

Hi,

On 2020/7/2 21:55, Keqian Zhu wrote:
> For that using arm64 DBM to log dirty pages has the side effect
> of long time dirty log sync, we should give userspace opportunity
> to enable or disable this feature, to realize some policy.
> 
> This feature is disabled by default.
> 
> Signed-off-by: Keqian Zhu <zhukeqian1@xxxxxxxxxx>
> Signed-off-by: Peng Liang <liangpeng10@xxxxxxxxxx>
> ---
>  arch/arm64/include/asm/kvm_host.h |  1 +
>  arch/arm64/kvm/arm.c              | 35 +++++++++++++++++++++++++++++++
>  arch/arm64/kvm/mmu.c              | 22 +++++++++++++++++++
>  arch/arm64/kvm/reset.c            |  5 +++++
>  include/uapi/linux/kvm.h          |  1 +
>  tools/include/uapi/linux/kvm.h    |  1 +
>  6 files changed, 65 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 86b9c210ba43..69a5317c7049 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -481,6 +481,7 @@ u64 __kvm_call_hyp(void *hypfn, ...);
>  void force_vm_exit(const cpumask_t *mask);
>  void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
>  void kvm_mmu_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot);
> +void kvm_mmu_sync_dirty_log_all(struct kvm *kvm);
>  
>  int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
>  		int exception_index);
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index fefa5406e037..9e3f765d5467 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -78,6 +78,11 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
>  			    struct kvm_enable_cap *cap)
>  {
>  	int r;
> +#ifdef CONFIG_ARM64_HW_AFDBM
> +	int i;
> +	struct kvm_vcpu *vcpu;
> +	bool enable_hw_dirty_log;
> +#endif
>  
>  	if (cap->flags)
>  		return -EINVAL;
> @@ -87,6 +92,36 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
>  		r = 0;
>  		kvm->arch.return_nisv_io_abort_to_user = true;
>  		break;
> +#ifdef CONFIG_ARM64_HW_AFDBM
> +	case KVM_CAP_ARM_HW_DIRTY_LOG:
> +		if (!arm_mmu_hw_dbm_supported() || (cap->args[0] & ~0x1))
> +			r = -EINVAL;
Miss "break" here :-( . Code is converted from "return -EINVAL".
> +
> +		enable_hw_dirty_log = !!(cap->args[0] & 0x1);
> +		if (!!(kvm->arch.vtcr & VTCR_EL2_HD) != enable_hw_dirty_log) {
> +			if (enable_hw_dirty_log)
> +				kvm->arch.vtcr |= VTCR_EL2_HD;
> +			else
> +				kvm->arch.vtcr &= ~VTCR_EL2_HD;
> +
> +			/*
> +			 * We should kick vcpus out of guest mode here to
> +			 * load new vtcr value to vtcr_el2 register when
> +			 * re-enter guest mode.
> +			 */
> +			kvm_for_each_vcpu(i, vcpu, kvm)
> +				kvm_vcpu_kick(vcpu);
> +
> +			if (!enable_hw_dirty_log) {
> +				mutex_lock(&kvm->slots_lock);
> +				kvm_mmu_sync_dirty_log_all(kvm);
> +				mutex_unlock(&kvm->slots_lock);
> +			}
> +		}
> +
> +		r = 0;
> +		break;
> +#endif
>  	default:
>  		r = -EINVAL;
>  		break;
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index adfa62f1fced..1a48554accb0 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -2590,6 +2590,28 @@ void kvm_mmu_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
>  	spin_unlock(&kvm->mmu_lock);
>  	srcu_read_unlock(&kvm->srcu, srcu_idx);
>  }
> +
> +/**
> + * kvm_mmu_sync_dirty_log_all() - synchronize dirty log from PTEs for whole VM
> + * @kvm:	The KVM pointer
> + *
> + * Called with kvm->slots_lock mutex acquired
> + */
> +void kvm_mmu_sync_dirty_log_all(struct kvm *kvm)
> +{
> +	struct kvm_memslots *slots = kvm_memslots(kvm);
> +	struct kvm_memory_slot *memslots = slots->memslots;
> +	struct kvm_memory_slot *memslot;
> +	int slot;
> +
> +	if (unlikely(!slots->used_slots))
> +		return;
> +
> +	for (slot = 0; slot < slots->used_slots; slot++) {
> +		memslot = &memslots[slot];
> +		kvm_mmu_sync_dirty_log(kvm, memslot);
> +	}
> +}
>  #endif /* CONFIG_ARM64_HW_AFDBM */
>  
>  void kvm_arch_commit_memory_region(struct kvm *kvm,
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index d3b209023727..a3be703dd54b 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -83,6 +83,11 @@ int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  		r = has_vhe() && system_supports_address_auth() &&
>  				 system_supports_generic_auth();
>  		break;
> +#ifdef CONFIG_ARM64_HW_AFDBM
> +	case KVM_CAP_ARM_HW_DIRTY_LOG:
> +		r = arm_mmu_hw_dbm_supported();
> +		break;
> +#endif /* CONFIG_ARM64_HW_AFDBM */
>  	default:
>  		r = 0;
>  	}
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 4fdf30316582..e0b12c43397b 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1031,6 +1031,7 @@ struct kvm_ppc_resize_hpt {
>  #define KVM_CAP_PPC_SECURE_GUEST 181
>  #define KVM_CAP_HALT_POLL 182
>  #define KVM_CAP_ASYNC_PF_INT 183
> +#define KVM_CAP_ARM_HW_DIRTY_LOG 184
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>  
> diff --git a/tools/include/uapi/linux/kvm.h b/tools/include/uapi/linux/kvm.h
> index 4fdf30316582..e0b12c43397b 100644
> --- a/tools/include/uapi/linux/kvm.h
> +++ b/tools/include/uapi/linux/kvm.h
> @@ -1031,6 +1031,7 @@ struct kvm_ppc_resize_hpt {
>  #define KVM_CAP_PPC_SECURE_GUEST 181
>  #define KVM_CAP_HALT_POLL 182
>  #define KVM_CAP_ASYNC_PF_INT 183
> +#define KVM_CAP_ARM_HW_DIRTY_LOG 184
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>  
>