Re: [PATCH v10 4/7] KVM: arm64: Enable ring-based dirty memory tracking

[Zenghui Yu <yuzenghui@huawei.com>]

Hi Gavin,

On 2022/11/10 18:49, Gavin Shan wrote:
> Enable ring-based dirty memory tracking on ARM64:
> 
>   - Enable CONFIG_HAVE_KVM_DIRTY_RING_ACQ_REL.
> 
>   - Enable CONFIG_NEED_KVM_DIRTY_RING_WITH_BITMAP.
> 
>   - Set KVM_DIRTY_LOG_PAGE_OFFSET for the ring buffer's physical page
>     offset.
> 
>   - Add ARM64 specific kvm_arch_allow_write_without_running_vcpu() to
>     keep the site of saving vgic/its tables out of the no-running-vcpu
>     radar.

And we have KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES.. On receiving it, the
emulated VGIC will write all pending bits (if any) into pending tables
(which reside in guest memory) and doesn't require a running vcpu
context.

The no-running-vcpu WARN can be triggered with the
kvm-unit-tests/its-pending-migration case. I run it using QEMU, which
has nothing to do with the dirty ring atm.

Or are there already discussions about it that I haven't noticed?

|void mark_page_dirty_in_slot(struct kvm *kvm,
|			     const struct kvm_memory_slot *memslot,
|			     gfn_t gfn)
|{
|	WARN_ON_ONCE(!vcpu && !kvm_arch_allow_write_without_running_vcpu(kvm));