VMCI: dma dg: set OS page size

Tell the device the page size used by the OS.
Reviewed-by: Vishnu Dasa <vdasa@vmware.com>
Signed-off-by: Jorgen Hansen <jhansen@vmware.com>
Link: https://lore.kernel.org/r/20220207102725.2742-5-jhansen@vmware.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/vmw_vmci/vmci_guest.c

@@ -578,6 +578,10 @@ static int vmci_guest_probe_device(struct pci_dev *pdev,
 	/* Let the host know which capabilities we intend to use. */
 	vmci_write_reg(vmci_dev, caps_in_use, VMCI_CAPS_ADDR);
 
+	/* Let the device know the size for pages passed down. */
+	if (caps_in_use & VMCI_CAPS_DMA_DATAGRAM)
+		vmci_write_reg(vmci_dev, PAGE_SHIFT, VMCI_GUEST_PAGE_SHIFT);
+
 	/* Set up global device so that we can start sending datagrams */
 	spin_lock_irq(&vmci_dev_spinlock);
 	vmci_dev_g = vmci_dev;

include/linux/vmw_vmci_defs.h

@@ -21,6 +21,7 @@
 #define VMCI_CAPS_ADDR          0x18
 #define VMCI_RESULT_LOW_ADDR    0x1c
 #define VMCI_RESULT_HIGH_ADDR   0x20
+#define VMCI_GUEST_PAGE_SHIFT   0x34
 
 /* Max number of devices. */
 #define VMCI_MAX_DEVICES 1