fix(virtio/pci): use volatile accesses for device features

Signed-off-by: Martin Kröning <[email protected]>

Author: mkroening

src/drivers/virtio/transport/pci.rs

@@ -528,19 +528,19 @@ impl ComCfg {
 		// Indicate device to show high 32 bits in device_feature field.
 		// See Virtio specification v1.1. - 4.1.4.3
 		memory_barrier();
-		self.com_cfg.device_feature_select = 1;
+	    unsafe { ptr::from_mut(&mut self.com_cfg.device_feature_select).write_volatile(1) };
 		memory_barrier();
 
 		// read high 32 bits of device features
-		let mut dev_feat = u64::from(self.com_cfg.device_feature) << 32;
+		let mut dev_feat = u64::from(unsafe { ptr::from_mut(&mut self.com_cfg.device_feature).read_volatile() }) << 32;
 
 		// Indicate device to show low 32 bits in device_feature field.
 		// See Virtio specification v1.1. - 4.1.4.3
-		self.com_cfg.device_feature_select = 0;
+	    unsafe { ptr::from_mut(&mut self.com_cfg.device_feature_select).write_volatile(0) };
 		memory_barrier();
 
 		// read low 32 bits of device features
-		dev_feat |= u64::from(self.com_cfg.device_feature);
+		dev_feat |= u64::from(unsafe { ptr::from_mut(&mut self.com_cfg.device_feature).read_volatile() });
 
 		dev_feat
 	}