KVM: MIPS: Add EVENTFD support which is needed by VHOST

Add EVENTFD support for KVM/MIPS, which is needed by VHOST. Tested on
Loongson-3 platform.

Reviewed-by: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Co-developed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-Id: <1590220602-3547-5-git-send-email-chenhc@lemote.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/mips/kvm/Kconfig

@@ -22,6 +22,7 @@ config KVM
 	select EXPORT_UASM
 	select PREEMPT_NOTIFIERS
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
+	select HAVE_KVM_EVENTFD
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select KVM_MMIO
 	select MMU_NOTIFIER

arch/mips/kvm/Makefile

@@ -2,7 +2,7 @@
 # Makefile for KVM support for MIPS
 #
 
-common-objs-y = $(addprefix ../../../virt/kvm/, kvm_main.o coalesced_mmio.o)
+common-objs-y = $(addprefix ../../../virt/kvm/, kvm_main.o coalesced_mmio.o eventfd.o)
 
 EXTRA_CFLAGS += -Ivirt/kvm -Iarch/mips/kvm
 

arch/mips/kvm/trap_emul.c

@@ -529,6 +529,9 @@ static int kvm_trap_emul_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_MIPS_TE:
 		r = 1;
 		break;
+	case KVM_CAP_IOEVENTFD:
+		r = 1;
+		break;
 	default:
 		r = 0;
 		break;

arch/mips/kvm/vz.c

@@ -2927,6 +2927,9 @@ static int kvm_vz_check_extension(struct kvm *kvm, long ext)
 		r = 2;
 		break;
 #endif
+	case KVM_CAP_IOEVENTFD:
+		r = 1;
+		break;
 	default:
 		r = 0;
 		break;