virtio: add clear_feature hook.

Change-Id: I282ffc65a7bd692145626ab4272c5df4a792e9d4
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2383
Reviewed-by: Adrien Destugues <[email protected]>
Reviewed-by: waddlesplash <[email protected]>

headers/private/virtio/virtio.h

@@ -101,6 +101,8 @@ typedef struct {
 	status_t (*negotiate_features)(virtio_device cookie, uint32 supported,
 		uint32* negotiated, const char* (*get_feature_name)(uint32));
 
+	status_t (*clear_feature)(virtio_device cookie, uint32 feature);
+
 	status_t (*read_device_config)(virtio_device cookie, uint8 offset,
 		void* buffer, size_t bufferSize);
 	status_t (*write_device_config)(virtio_device cookie, uint8 offset,

src/add-ons/kernel/bus_managers/virtio/VirtioDevice.cpp

@@ -126,6 +126,14 @@ VirtioDevice::NegotiateFeatures(uint32 supported, uint32* negotiated,
 }
 
 
+status_t
+VirtioDevice::ClearFeature(uint32 feature)
+{
+	fFeatures &= ~feature;
+	return fController->write_guest_features(fCookie, fFeatures);
+}
+
+
 status_t
 VirtioDevice::ReadDeviceConfig(uint8 offset, void* buffer, size_t bufferSize)
 {

src/add-ons/kernel/bus_managers/virtio/VirtioModule.cpp

@@ -63,6 +63,16 @@ virtio_negotiate_features(void* _device, uint32 supported,
 }
 
 
+status_t
+virtio_clear_feature(void* _device, uint32 feature)
+{
+	CALLED();
+	VirtioDevice *device = (VirtioDevice *)_device;
+
+	return device->ClearFeature(feature);
+}
+
+
 status_t
 virtio_read_device_config(void* _device, uint8 offset, void* buffer,
 		size_t bufferSize)
@@ -275,6 +285,7 @@ virtio_device_interface virtio_device_module = {
 	},
 
 	virtio_negotiate_features,
+	virtio_clear_feature,
 	virtio_read_device_config,
 	virtio_write_device_config,
 	virtio_alloc_queues,

src/add-ons/kernel/bus_managers/virtio/VirtioPrivate.h

@@ -48,6 +48,7 @@ public:
 			status_t 			NegotiateFeatures(uint32 supported,
 									uint32* negotiated,
 									const char* (*get_feature_name)(uint32));
+			status_t 			ClearFeature(uint32 feature);
 
 			status_t			ReadDeviceConfig(uint8 offset, void* buffer,
 									size_t bufferSize);