A new ioctl (KVM_CAP_ARM_HW_DIRTY_STATE_TRACK) provides a mechanism for
userspace to configure the HDBSS buffer size during live migration,
enabling hardware-assisted dirty page tracking.

Signed-off-by: eillon <yezhenyu2@huawei.com>
Signed-off-by: Tian Zheng <zhengtian10@huawei.com>
---
 Documentation/virt/kvm/api.rst | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 57061fa29e6a..25d60ff136e9 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -8703,6 +8703,21 @@ This capability indicate to the userspace whether a PFNMAP memory region
 can be safely mapped as cacheable. This relies on the presence of
 force write back (FWB) feature support on the hardware.

+7.44 KVM_CAP_ARM_HW_DIRTY_STATE_TRACK
+:Architectures: arm64
+:Type: VM
+:Parameters: args[0] is the allocation order determining HDBSS buffer size
+:Returns: 0 on success, negative value on failure
+
+Enables hardware-assisted dirty page tracking via the Hardware Dirty State
+Tracking Structure (HDBSS).
+
+When live migration is initiated, userspace can enable this feature by
+setting KVM_CAP_ARM_HW_DIRTY_STATE_TRACK through IOCTL. KVM will allocate
+per-vCPU HDBSS buffers.
+
+The feature is disabled by invoking the ioctl again.
+
 8. Other capabilities.
 ======================

--
2.33.0