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Message-ID: <F9E001219150CB45BEDC82A650F360C901497698@G9W0717.americas.hpqcorp.net>
Date: Fri, 11 Jan 2013 08:53:02 +0000
From: "Pandarathil, Vijaymohan R" <vijaymohan.pandarathil@...com>
To: Alex Williamson <alex.williamson@...hat.com>
CC: Bjorn Helgaas <bhelgaas@...gle.com>,
Gleb Natapov <gleb@...hat.com>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"qemu-devel@...gnu.org" <qemu-devel@...gnu.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 2/2] QEMU-AER: Qemu changes to support AER for VFIO-PCI
devices
> -----Original Message-----
> From: Alex Williamson [mailto:alex.williamson@...hat.com]
> Sent: Wednesday, January 09, 2013 10:08 AM
> To: Pandarathil, Vijaymohan R
> Cc: Bjorn Helgaas; Gleb Natapov; kvm@...r.kernel.org; qemu-
> devel@...gnu.org; linux-pci@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH 2/2] QEMU-AER: Qemu changes to support AER for VFIO-PCI
> devices
>
> On Wed, 2013-01-09 at 06:26 +0000, Pandarathil, Vijaymohan R wrote:
> > - Create eventfd per vfio device assigned to a guest and register an
> > event handler
> >
> > - This fd is passed to the vfio_pci driver through a new ioctl
> >
> > - When the device encounters an error, the eventfd is signaled
> > and the qemu eventfd handler gets invoked.
> >
> > - In the handler decide what action to take. Current action taken
> > is to terminate the guest.
> >
> > Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@...com>
> > ---
> > hw/vfio_pci.c | 56
> ++++++++++++++++++++++++++++++++++++++++++++++
> > linux-headers/linux/vfio.h | 9 ++++++++
> > 2 files changed, 65 insertions(+)
> >
> > diff --git a/hw/vfio_pci.c b/hw/vfio_pci.c
> > index 28c8303..9c3c28b 100644
> > --- a/hw/vfio_pci.c
> > +++ b/hw/vfio_pci.c
> > @@ -38,6 +38,7 @@
> > #include "qemu/error-report.h"
> > #include "qemu/queue.h"
> > #include "qemu/range.h"
> > +#include "sysemu/sysemu.h"
> >
> > /* #define DEBUG_VFIO */
> > #ifdef DEBUG_VFIO
> > @@ -130,6 +131,8 @@ typedef struct VFIODevice {
> > QLIST_ENTRY(VFIODevice) next;
> > struct VFIOGroup *group;
> > bool reset_works;
> > + EventNotifier errfd;
>
> Misleading name, it's an EventNotifier not an fd.
Will make the change.
>
> > + __u32 dev_info_flags;
> > } VFIODevice;
> >
> > typedef struct VFIOGroup {
> > @@ -1805,6 +1808,8 @@ static int vfio_get_device(VFIOGroup *group, const
> char *name, VFIODevice *vdev)
> > DPRINTF("Device %s flags: %u, regions: %u, irgs: %u\n", name,
> > dev_info.flags, dev_info.num_regions, dev_info.num_irqs);
> >
> > + vdev->dev_info_flags = dev_info.flags;
> > +
>
> We test the VFIO_DEVICE_FLAGS_RESET elsewhere by caching the bit into a
> variable, why not do that here too?
I was wondering if there was any specific reason to cache the bit into a separate variable. Wouldn't a flags field which can contain the specific bit be more apt ?
>
> > if (!(dev_info.flags & VFIO_DEVICE_FLAGS_PCI)) {
> > error_report("vfio: Um, this isn't a PCI device\n");
> > goto error;
> > @@ -1900,6 +1905,55 @@ static void vfio_put_device(VFIODevice *vdev)
> > }
> > }
> >
> > +static void vfio_errfd_handler(void *opaque)
> > +{
> > + VFIODevice *vdev = opaque;
> > +
> > + if (!event_notifier_test_and_clear(&vdev->errfd)) {
> > + return;
> > + }
> > +
> > + /*
> > + * TBD. Retrieve the error details and decide what action
> > + * needs to be taken. One of the actions could be to pass
> > + * the error to the guest and have the guest driver recover
> > + * the error. This requires that PCIe capabilities be
> > + * exposed to the guest. At present, we just terminate the
> > + * guest to contain the error.
> > + */
> > + error_report("%s(%04x:%02x:%02x.%x) "
> > + "Unrecoverable error detected... Terminating guest\n",
> > + __func__, vdev->host.domain, vdev->host.bus, vdev->host.slot,
> > + vdev->host.function);
> > +
> > + qemu_system_shutdown_request();
>
> I would have figured hw_error
Hw_error() is probably more appropriate. Will make the change.
>
> > + return;
> > +}
> > +
> > +static void vfio_register_errfd(VFIODevice *vdev)
> > +{
> > + int32_t pfd;
>
> "pfd" is used elsewhere in vfio as "Pointer to FD", this is just a fd.
Will change.
>
> > + int ret;
> > +
> > + if (!(vdev->dev_info_flags & VFIO_DEVICE_FLAGS_AER_NOTIFY)) {
> > + error_report("vfio: Warning: Error notification not supported
> for the device\n");
>
> This should probably just be a debug print.
Okay.
>
> > + return;
> > + }
> > + if (event_notifier_init(&vdev->errfd, 0)) {
> > + error_report("vfio: Warning: Unable to init event notifier for
> error detection\n");
> > + return;
> > + }
> > + pfd = event_notifier_get_fd(&vdev->errfd);
> > + qemu_set_fd_handler(pfd, vfio_errfd_handler, NULL, vdev);
> > +
> > + ret = ioctl(vdev->fd, VFIO_DEVICE_SET_ERRFD, pfd);
> > + if (ret) {
> > + error_report("vfio: Warning: Failed to setup error fd: %d\n",
> ret);
> > + qemu_set_fd_handler(pfd, NULL, NULL, vdev);
> > + event_notifier_cleanup(&vdev->errfd);
> > + }
> > + return;
> > +}
> > static int vfio_initfn(PCIDevice *pdev)
> > {
> > VFIODevice *pvdev, *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
> > @@ -2010,6 +2064,8 @@ static int vfio_initfn(PCIDevice *pdev)
> > }
> > }
> >
> > + vfio_register_errfd(vdev);
> > +
>
> No cleanup in exitfn?! Thanks,
Missed that. Will fix.
Vijay
>
> Alex
>
> > return 0;
> >
> > out_teardown:
> > diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h
> > index 4758d1b..0ca4eeb 100644
> > --- a/linux-headers/linux/vfio.h
> > +++ b/linux-headers/linux/vfio.h
> > @@ -147,6 +147,7 @@ struct vfio_device_info {
> > __u32 flags;
> > #define VFIO_DEVICE_FLAGS_RESET (1 << 0) /* Device supports reset */
> > #define VFIO_DEVICE_FLAGS_PCI (1 << 1) /* vfio-pci device */
> > +#define VFIO_DEVICE_FLAGS_AER_NOTIFY (1 << 2) /* Supports aer
> notification */
> > __u32 num_regions; /* Max region index + 1 */
> > __u32 num_irqs; /* Max IRQ index + 1 */
> > };
> > @@ -288,6 +289,14 @@ struct vfio_irq_set {
> > */
> > #define VFIO_DEVICE_RESET _IO(VFIO_TYPE, VFIO_BASE + 11)
> >
> > +/**
> > + * VFIO_DEVICE_SET_ERRFD - _IO(VFIO_TYPE, VFIO_BASE + 12)
> > + *
> > + * Pass the eventfd to the vfio-pci driver for signalling any device
> > + * error notifications
> > + */
> > +#define VFIO_DEVICE_SET_ERRFD _IO(VFIO_TYPE, VFIO_BASE + 12)
> > +
> > /*
> > * The VFIO-PCI bus driver makes use of the following fixed region and
> > * IRQ index mapping. Unimplemented regions return a size of zero.
>
>
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