On Mon, 2013-09-30 at 12:49 +0200, Laszlo Ersek wrote:
> On 09/28/13 20:51, Mark Salter wrote:
> > On Fri, 2013-09-27 at 02:31 +0200, Laszlo Ersek wrote:
> >> Hi Mark,
> >>
> >> just my 2 cents:
> >>
> >> On 09/26/13 21:33, Mark Salter wrote:
> >>> I've been trying out this patch series on AArch64 foundation model.
> >>> I have UEFI booting a linux kernel image in an EFI system partition.
> >>> But the kernel itself doesn't see the virtio device. If I boot with
> >>> an UEFI image without virtio support built in, the same kernel does
> >>> see the virtio disk device.
> >>>
> >>> So, could this be a case of the UEFI virtio driver not releasing the
> >>> virtio device?
> >>
> >> Interesting. We'd only know for sure if we debugged into the kernel
> >> ("drivers/virtio/virtio_mmio.c" more precisely).
> >
> > Well, the virtio_blk probe fails with error of -ENOENT. I tracked that
> > down to vm_setup_vq() in virtio_mmio.c:
> >
> > /* Queue shouldn't already be set up. */
> > if (readl(vm_dev->base + VIRTIO_MMIO_QUEUE_PFN)) {
> > err = -ENOENT;
> > goto error_available;
> > }
> >
> > --Mark
>
> Could be a problem in the AArch64 foundation model. Both virtio-mmio and
> virtio-pci in the guest seem to have good virtio_config_ops.reset
> implementation, and the problem is not reproducible on virtio-pci. Maybe
> the host/emulator is not forgetful enough.
My thought was the foundation model as well. But virtio spec 0.9.5,
appendix X, under QueuePFN description says:
When Guest stops using the queue it must write zero (0x0) to
this register.
I added an ExitBootServices event handler to do this and the kernel is
happy with virtio after that. Patch follows although I don't know my way
around EDK2, so it probably isn't the proper way.
diff --git a/OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDevice.c
b/OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDevice.c
index 5c88419..2d75d67 100644
--- a/OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDevice.c
+++ b/OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDevice.c
@@ -20,6 +20,11 @@
#include "VirtioMmioDevice.h"
+//
+// Notifications
+//
+EFI_EVENT EfiExitBootServicesEvent = (EFI_EVENT)NULL;
+
static VIRTIO_DEVICE_PROTOCOL mMmioDeviceProtocolTemplate = {
0, // SubSystemDeviceId
VirtioMmioGetDeviceFeatures, // GetDeviceFeatures
@@ -120,6 +125,22 @@ VirtioMmioUninit (
// the old comms area.
//
VIRTIO_CFG_WRITE (Device, VIRTIO_MMIO_OFFSET_STATUS, 0);
+ VIRTIO_CFG_WRITE (Device, VIRTIO_MMIO_OFFSET_QUEUE_PAGE_OFF, 0);
+}
+
+/***************************************
+ * This function should be called
+ * on Event: ExitBootServices
+ * to free up memory, stop the driver
+ * and uninstall the protocols
+ ***************************************/
+VOID
+VirtioMmioExitBootServicesEvent (
+ IN EFI_EVENT Event,
+ IN VOID *Context
+ )
+{
+ VirtioMmioUninit (Context);
}
EFI_STATUS
@@ -165,6 +186,21 @@ VirtioMmioInstallDevice (
goto UninstallVirtio;
}
+ // Register for an ExitBootServicesEvent
+ // When ExitBootServices starts, this function here will make sure that the
mmio
+ // interface is shutdown.
+ Status = gBS->CreateEvent (
+ EVT_SIGNAL_EXIT_BOOT_SERVICES,
+ TPL_NOTIFY,
+ VirtioMmioExitBootServicesEvent, VirtIo,
+ &EfiExitBootServicesEvent
+ );
+
+ if (EFI_ERROR(Status)) {
+ DEBUG((DEBUG_ERROR, "VirtioMmioInstallDevice: Can not install the
ExitBootServicesEvent handler. Exit Status=%r\n", Status));
+ goto UninstallVirtio;
+ }
+
return EFI_SUCCESS;
UninstallVirtio:
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