[PATCH 17/19] docs: virt: api.rst: Document the new KVM_{G, S}ET_XSAVE2 ioctls

[Yang Zhong]

From: Jing Liu <jing2.liu@xxxxxxxxx>

Document the detailed information of the new KVM_{G, S}ET_XSAVE2 ioctls.

Signed-off-by: Jing Liu <jing2.liu@xxxxxxxxx>
Signed-off-by: Yang Zhong <yang.zhong@xxxxxxxxx>
---
 Documentation/virt/kvm/api.rst | 47 ++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index aeeb071c7688..39dfd867e429 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -1569,6 +1569,8 @@ otherwise it will return EBUSY error.
   };
 
 This ioctl would copy current vcpu's xsave struct to the userspace.
+Application should use KVM_GET_XSAVE2 if xsave states are larger than
+4KB.
 
 
 4.43 KVM_SET_XSAVE
@@ -1588,6 +1590,8 @@ This ioctl would copy current vcpu's xsave struct to the userspace.
   };
 
 This ioctl would copy userspace's xsave struct to the kernel.
+Application should use KVM_SET_XSAVE2 if xsave states are larger than
+4KB.
 
 
 4.44 KVM_GET_XCRS
@@ -7484,3 +7488,46 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset
 of the result of KVM_CHECK_EXTENSION.  KVM will forward to userspace
 the hypercalls whose corresponding bit is in the argument, and return
 ENOSYS for the others.
+
+8.35 KVM_GET_XSAVE2
+-------------------
+
+:Capability: KVM_CAP_XSAVE2
+:Architectures: x86
+:Type: vcpu ioctl
+:Parameters: struct kvm_xsave2 (in)
+:Returns: 0 on success, -1 on error
+
+
+::
+
+  struct kvm_xsave2 {
+	__u32 size;
+	__u8 state[0];
+  };
+
+This ioctl is used for copying current vcpu's xsave struct to the
+userspace when xsave state size is larger than 4KB. Application code
+should set the 'size' member which indicates the size of xsave state
+and KVM copies the xsave state into the 'state' region.
+
+8.36 KVM_SET_XSAVE2
+-------------------
+
+:Capability: KVM_CAP_XSAVE2
+:Architectures: x86
+:Type: vcpu ioctl
+:Parameters: struct kvm_xsave2 (out)
+:Returns: 0 on success, -1 on error
+
+
+::
+
+  struct kvm_xsave2 {
+	__u32 size;
+	__u8 state[0];
+  };
+
+This ioctl is used for copying userspace's xsave struct to the kernel
+when xsave size is larger than 4KB. Application code should set the
+'size' member which indicates the size of xsave state.