kvm: nVMX: Introduce KVM_CAP_NESTED_STATE

For nested virtualization L0 KVM is managing a bit of state for L2 guests,
this state can not be captured through the currently available IOCTLs. In
fact the state captured through all of these IOCTLs is usually a mix of L1
and L2 state. It is also dependent on whether the L2 guest was running at
the moment when the process was interrupted to save its state.

With this capability, there are two new vcpu ioctls: KVM_GET_NESTED_STATE
and KVM_SET_NESTED_STATE. These can be used for saving and restoring a VM
that is in VMX operation.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Jim Mattson <jmattson@google.com>
[karahmed@ - rename structs and functions and make them ready for AMD and
             address previous comments.
           - handle nested.smm state.
           - rebase & a bit of refactoring.
           - Merge 7/8 and 8/8 into one patch. ]
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index cb8db4f9d097..7b83b176c662 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3561,6 +3561,62 @@ Returns: 0 on success,
 	-ENOENT on deassign if the conn_id isn't registered
 	-EEXIST on assign if the conn_id is already registered
 
+4.114 KVM_GET_NESTED_STATE
+
+Capability: KVM_CAP_NESTED_STATE
+Architectures: x86
+Type: vcpu ioctl
+Parameters: struct kvm_nested_state (in/out)
+Returns: 0 on success, -1 on error
+Errors:
+  E2BIG:     the total state size (including the fixed-size part of struct
+             kvm_nested_state) exceeds the value of 'size' specified by
+             the user; the size required will be written into size.
+
+struct kvm_nested_state {
+	__u16 flags;
+	__u16 format;
+	__u32 size;
+	union {
+		struct kvm_vmx_nested_state vmx;
+		struct kvm_svm_nested_state svm;
+		__u8 pad[120];
+	};
+	__u8 data[0];
+};
+
+#define KVM_STATE_NESTED_GUEST_MODE	0x00000001
+#define KVM_STATE_NESTED_RUN_PENDING	0x00000002
+
+#define KVM_STATE_NESTED_SMM_GUEST_MODE	0x00000001
+#define KVM_STATE_NESTED_SMM_VMXON	0x00000002
+
+struct kvm_vmx_nested_state {
+	__u64 vmxon_pa;
+	__u64 vmcs_pa;
+
+	struct {
+		__u16 flags;
+	} smm;
+};
+
+This ioctl copies the vcpu's nested virtualization state from the kernel to
+userspace.
+
+The maximum size of the state, including the fixed-size part of struct
+kvm_nested_state, can be retrieved by passing KVM_CAP_NESTED_STATE to
+the KVM_CHECK_EXTENSION ioctl().
+
+4.115 KVM_SET_NESTED_STATE
+
+Capability: KVM_CAP_NESTED_STATE
+Architectures: x86
+Type: vcpu ioctl
+Parameters: struct kvm_nested_state (in)
+Returns: 0 on success, -1 on error
+
+This copies the vcpu's kvm_nested_state struct from userspace to the kernel.  For
+the definition of struct kvm_nested_state, see KVM_GET_NESTED_STATE.
 
 5. The kvm_run structure
 ------------------------