VMCI: dma dg: detect DMA datagram capability

Detect the VMCI DMA datagram capability, and if present, ack it
to the device.
Reviewed-by: Vishnu Dasa <vdasa@vmware.com>
Signed-off-by: Jorgen Hansen <jhansen@vmware.com>
Link: https://lore.kernel.org/r/20220207102725.2742-4-jhansen@vmware.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/vmw_vmci/vmci_guest.c

@@ -562,6 +562,17 @@ static int vmci_guest_probe_device(struct pci_dev *pdev,
 		}
 	}
 
+	if (mmio_base != NULL) {
+		if (capabilities & VMCI_CAPS_DMA_DATAGRAM) {
+			caps_in_use |= VMCI_CAPS_DMA_DATAGRAM;
+		} else {
+			dev_err(&pdev->dev,
+				"Missing capability: VMCI_CAPS_DMA_DATAGRAM\n");
+			error = -ENXIO;
+			goto err_free_data_buffer;
+		}
+	}
+
 	dev_info(&pdev->dev, "Using capabilities 0x%x\n", caps_in_use);
 
 	/* Let the host know which capabilities we intend to use. */

include/linux/vmw_vmci_defs.h

@@ -39,6 +39,7 @@
 #define VMCI_CAPS_DATAGRAM      BIT(2)
 #define VMCI_CAPS_NOTIFICATIONS BIT(3)
 #define VMCI_CAPS_PPN64         BIT(4)
+#define VMCI_CAPS_DMA_DATAGRAM  BIT(5)
 
 /* Interrupt Cause register bits. */
 #define VMCI_ICR_DATAGRAM      BIT(0)