[PATCH v1] ARM/ARM64: support KVM_IOEVENTFD

[Ming Lei]

>From Documentation/virtual/kvm/api.txt, all ARCHs should support
ioeventfd.

Also ARM VM has supported PCI bus already, and ARM64 will do too,
ioeventfd is required for some popular devices, like virtio-blk
and virtio-scsi dataplane in QEMU.

Without this patch, virtio-blk-pci dataplane can't work in QEMU.

This patch has been tested on both ARM and ARM64.

Signed-off-by: Ming Lei <ming.lei at canonical.com>
---
v1:
	- make eventfd.o built in ARM64
 arch/arm/kvm/Kconfig    |    1 +
 arch/arm/kvm/Makefile   |    2 +-
 arch/arm/kvm/arm.c      |    1 +
 arch/arm/kvm/mmio.c     |   19 +++++++++++++++++++
 arch/arm64/kvm/Kconfig  |    1 +
 arch/arm64/kvm/Makefile |    2 +-
 6 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
index 466bd29..25bd83a 100644
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -23,6 +23,7 @@ config KVM
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select KVM_MMIO
 	select KVM_ARM_HOST
+	select HAVE_KVM_EVENTFD
 	depends on ARM_VIRT_EXT && ARM_LPAE
 	---help---
 	  Support hosting virtualized guest machines. You will also
diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile
index f7057ed..859db09 100644
--- a/arch/arm/kvm/Makefile
+++ b/arch/arm/kvm/Makefile
@@ -15,7 +15,7 @@ AFLAGS_init.o := -Wa,-march=armv7-a$(plus_virt)
 AFLAGS_interrupts.o := -Wa,-march=armv7-a$(plus_virt)
 
 KVM := ../../../virt/kvm
-kvm-arm-y = $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o
+kvm-arm-y = $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o
 
 obj-y += kvm-arm.o init.o interrupts.o
 obj-y += arm.o handle_exit.o guest.o mmu.o emulate.o reset.o
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 9e193c8..d90d989 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -172,6 +172,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_IRQCHIP:
 		r = vgic_present;
 		break;
+	case KVM_CAP_IOEVENTFD:
 	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_USER_MEMORY:
 	case KVM_CAP_SYNC_MMU:
diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
index 4cb5a93..ee332a7 100644
--- a/arch/arm/kvm/mmio.c
+++ b/arch/arm/kvm/mmio.c
@@ -162,6 +162,21 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	return 0;
 }
 
+static int handle_io_bus_rw(struct kvm_vcpu *vcpu, gpa_t addr,
+			    int len, void *val, bool write)
+{
+	int idx, ret;
+
+	idx = srcu_read_lock(&vcpu->kvm->srcu);
+	if (write)
+		ret = kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, len, val);
+	else
+		ret = kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, addr, len, val);
+	srcu_read_unlock(&vcpu->kvm->srcu, idx);
+
+	return ret;
+}
+
 int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
 		 phys_addr_t fault_ipa)
 {
@@ -200,6 +215,10 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
 	if (vgic_handle_mmio(vcpu, run, &mmio))
 		return 1;
 
+	if (!handle_io_bus_rw(vcpu, fault_ipa, mmio.len, &mmio.data,
+	    mmio.is_write))
+		return 1;
+
 	kvm_prepare_mmio(run, &mmio);
 	return 0;
 }
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 8ba85e9..642f57c 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -26,6 +26,7 @@ config KVM
 	select KVM_ARM_HOST
 	select KVM_ARM_VGIC
 	select KVM_ARM_TIMER
+	select HAVE_KVM_EVENTFD
 	---help---
 	  Support hosting virtualized guest machines.
 
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 32a0961..2e6b827 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -11,7 +11,7 @@ ARM=../../../arch/arm/kvm
 
 obj-$(CONFIG_KVM_ARM_HOST) += kvm.o
 
-kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o
+kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o
 kvm-$(CONFIG_KVM_ARM_HOST) += $(ARM)/arm.o $(ARM)/mmu.o $(ARM)/mmio.o
 kvm-$(CONFIG_KVM_ARM_HOST) += $(ARM)/psci.o $(ARM)/perf.o
 
-- 
1.7.9.5