Re: [PATCH v8 17/22] vfio-pci/zdev: add open/close device hooks

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On 5/24/22 5:08 PM, Jason Gunthorpe wrote:
On Tue, May 24, 2022 at 02:59:02PM -0400, Matthew Rosato wrote:
During vfio-pci open_device, pass the KVM associated with the vfio group
(if one exists).  This is needed in order to pass a special indicator
(GISA) to firmware to allow zPCI interpretation facilities to be used
for only the specific KVM associated with the vfio-pci device.  During
vfio-pci close_device, unregister the notifier.

Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
  arch/s390/include/asm/pci.h      |  2 ++
  drivers/vfio/pci/vfio_pci_core.c | 11 ++++++++++-
  drivers/vfio/pci/vfio_pci_zdev.c | 27 +++++++++++++++++++++++++++
  include/linux/vfio_pci_core.h    | 12 ++++++++++++
  4 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index 85eb0ef9d4c3..67fbce1ea0c9 100644
+++ b/arch/s390/include/asm/pci.h
@@ -5,6 +5,7 @@
  #include <linux/pci.h>
  #include <linux/mutex.h>
  #include <linux/iommu.h>
+#include <linux/notifier.h>
  #include <linux/pci_hotplug.h>
  #include <asm-generic/pci.h>
  #include <asm/pci_clp.h>
@@ -195,6 +196,7 @@ struct zpci_dev {
  	struct s390_domain *s390_domain; /* s390 IOMMU domain data */
  	struct kvm_zdev *kzdev;
  	struct mutex kzdev_lock;
+	struct notifier_block nb; /* vfio notifications */

This is obsolete now right? Same for the #include ?

Of course, I forgot to remove them...  Will do


@@ -418,6 +424,9 @@ void vfio_pci_core_disable(struct vfio_pci_core_device *vdev)
vdev->needs_reset = true; + if (vfio_pci_zdev_release(vdev))
+		pci_info(pdev, "%s: Couldn't restore zPCI state\n", __func__);
+
  	/*
  	 * If we have saved state, restore it.  If we can reset the device,
  	 * even better.  Resetting with current state seems better than
diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
index ea4c0d2b0663..d0df85c8b204 100644
+++ b/drivers/vfio/pci/vfio_pci_zdev.c
@@ -11,6 +11,7 @@
  #include <linux/uaccess.h>
  #include <linux/vfio.h>
  #include <linux/vfio_zdev.h>
+#include <linux/kvm_host.h>
  #include <asm/pci_clp.h>
  #include <asm/pci_io.h>
@@ -136,3 +137,29 @@ int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev, return ret;
  }
+
+int vfio_pci_zdev_open(struct vfio_pci_core_device *vdev)
+{
+	struct zpci_dev *zdev = to_zpci(vdev->pdev);
+
+	if (!zdev)
+		return -ENODEV;
+
+	if (!vdev->vdev.kvm)
+		return 0;
+
+	return kvm_s390_pci_register_kvm(zdev, vdev->vdev.kvm);
+}
+
+int vfio_pci_zdev_release(struct vfio_pci_core_device *vdev)
+{
+	struct zpci_dev *zdev = to_zpci(vdev->pdev);

Keeping these functions named open_device/close_device wouuld probably
be clearer

Agreed, will rename vfio_pci_zdev_{open,close}_device


+	if (!zdev)
+		return -ENODEV;
+
+	if (!vdev->vdev.kvm)
+		return 0;
+
+	return kvm_s390_pci_unregister_kvm(zdev);
+}

Again this cannot fail, you should make it return void, not ignore the
failure - or at least push the ignoring the failure down to the place
that is causing this.

I'll move that handling into kvm_s390_pci_unregister_kvm and make vfio_pci_zdev_close_device return void / will remove the check for the rc in vfio_pci_core_disable.


Otherwise it looks fine to me, thanks


Thanks




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