linux-kernel - [PATCH] vfio/pci: Propagate ACPI notifications to the user-space

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Date:   Tue,  7 Mar 2023 22:05:53 +0000
From:   Grzegorz Jaszczyk <jaz@...ihalf.com>
To:     linux-kernel@...r.kernel.org, alex.williamson@...hat.com
Cc:     dmy@...ihalf.com, tn@...ihalf.com, dbehr@...gle.com,
        upstream@...ihalf.com, dtor@...gle.com, jgg@...pe.ca,
        kevin.tian@...el.com, cohuck@...hat.com, abhsahu@...dia.com,
        yishaih@...dia.com, yi.l.liu@...el.com, kvm@...r.kernel.org,
        Dominik Behr <dbehr@...omium.org>,
        Grzegorz Jaszczyk <jaz@...ihalf.com>
Subject: [PATCH] vfio/pci: Propagate ACPI notifications to the user-space

From: Dominik Behr <dbehr@...omium.org>

Hitherto there was no support for propagating ACPI notifications to the
guest drivers. In order to provide such support, install a handler for
notifications on an ACPI device during vfio-pci device registration. The
handler role is to propagate such ACPI notifications to the user-space
via acpi netlink events, which allows VMM to receive and propagate them
further to the VMs.

Thanks to the above, the actual driver for the pass-through device,
which belongs to the guest, can receive and react to device specific
notifications.

Signed-off-by: Dominik Behr <dbehr@...omium.org>
Co-developed-by: Grzegorz Jaszczyk <jaz@...ihalf.com>
Signed-off-by: Grzegorz Jaszczyk <jaz@...ihalf.com>
---
 drivers/vfio/pci/vfio_pci_core.c | 33 ++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index a5ab416cf476..92b8ed8d087c 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -10,6 +10,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/acpi.h>
 #include <linux/aperture.h>
 #include <linux/device.h>
 #include <linux/eventfd.h>
@@ -2120,10 +2121,20 @@ void vfio_pci_core_release_dev(struct vfio_device *core_vdev)
 }
 EXPORT_SYMBOL_GPL(vfio_pci_core_release_dev);
 
+static void vfio_pci_core_acpi_notify(acpi_handle handle, u32 event, void *data)
+{
+	struct vfio_pci_core_device *vdev = (struct vfio_pci_core_device *)data;
+	struct device *dev = &vdev->pdev->dev;
+
+	acpi_bus_generate_netlink_event("vfio_pci", dev_name(dev), event, 0);
+}
+
 int vfio_pci_core_register_device(struct vfio_pci_core_device *vdev)
 {
+	acpi_status status;
 	struct pci_dev *pdev = vdev->pdev;
 	struct device *dev = &pdev->dev;
+	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
 	int ret;
 
 	/* Drivers must set the vfio_pci_core_device to their drvdata */
@@ -2201,8 +2212,24 @@ int vfio_pci_core_register_device(struct vfio_pci_core_device *vdev)
 	ret = vfio_register_group_dev(&vdev->vdev);
 	if (ret)
 		goto out_power;
+
+	if (!adev) {
+		pci_info(pdev, "No ACPI companion");
+		return 0;
+	}
+
+	status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY,
+					vfio_pci_core_acpi_notify, (void *)vdev);
+
+	if (ACPI_FAILURE(status)) {
+		pci_err(pdev, "Failed to install notify handler");
+		goto out_group_register;
+	}
+
 	return 0;
 
+out_group_register:
+	vfio_unregister_group_dev(&vdev->vdev);
 out_power:
 	if (!disable_idle_d3)
 		pm_runtime_get_noresume(dev);
@@ -2216,6 +2243,12 @@ EXPORT_SYMBOL_GPL(vfio_pci_core_register_device);
 
 void vfio_pci_core_unregister_device(struct vfio_pci_core_device *vdev)
 {
+	struct acpi_device *adev = ACPI_COMPANION(&vdev->pdev->dev);
+
+	if (adev)
+		acpi_remove_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY,
+					   vfio_pci_core_acpi_notify);
+
 	vfio_pci_core_sriov_configure(vdev, 0);
 
 	vfio_unregister_group_dev(&vdev->vdev);
-- 
2.40.0.rc0.216.gc4246ad0f0-goog