KVM: introduce KVM_CAP_SET_GUEST_DEBUG2

This capability will allow the user to know which KVM_GUESTDBG_* bits
are supported.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210401135451.1004564-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Documentation/virt/kvm/api.rst

@@ -3357,6 +3357,9 @@ indicating the number of supported registers.
 For ppc, the KVM_CAP_PPC_GUEST_DEBUG_SSTEP capability indicates whether
 the single-step debug event (KVM_GUESTDBG_SINGLESTEP) is supported.
 
+Also when supported, KVM_CAP_SET_GUEST_DEBUG2 capability indicates the
+supported KVM_GUESTDBG_* bits in the control field.
+
 When debug events exit the main run loop with the reason
 KVM_EXIT_DEBUG with the kvm_debug_exit_arch part of the kvm_run
 structure containing architecture specific debug information.

include/uapi/linux/kvm.h

@@ -1078,6 +1078,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_DIRTY_LOG_RING 192
 #define KVM_CAP_X86_BUS_LOCK_EXIT 193
 #define KVM_CAP_PPC_DAWR1 194
+#define KVM_CAP_SET_GUEST_DEBUG2 195
 
 #ifdef KVM_CAP_IRQ_ROUTING