[PATCH V6 6/8] vfio, platform: make reset driver a requirement by default

Sinan Kaya
2016-05-28T22:01:16Z

The code was allowing platform devices to be used without a supporting
VFIO reset driver. The hardware can be left in some inconsistent state
after a guest machine abort.

The reset driver will put the hardware back to safe state and disable
interrupts before returning the control back to the host machine.

Adding a new reset_required kernel module option to AMBA and platform
VFIO drivers with a default value of true.

New requirements are:
1. A reset function needs to be implemented by the corresponding driver
via DT/ACPI.
2. The reset function needs to be discovered via DT/ACPI.

The probe of the driver will fail if any of the above conditions are
not satisfied.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
drivers/vfio/platform/vfio_amba.c | 5 +++++
drivers/vfio/platform/vfio_platform.c | 5 +++++
drivers/vfio/platform/vfio_platform_common.c | 14 +++++++++++---
drivers/vfio/platform/vfio_platform_private.h | 1 +
4 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/platform/vfio_amba.c b/drivers/vfio/platform/vfio_amba.c
index a66479b..7585902 100644
--- a/drivers/vfio/platform/vfio_amba.c
+++ b/drivers/vfio/platform/vfio_amba.c
@@ -23,6 +23,10 @@
#define DRIVER_AUTHOR "Antonios Motakis <a.motakis@virtualopensystems.com>"
#define DRIVER_DESC "VFIO for AMBA devices - User Level meta-driver"

+static bool reset_required = true;
+module_param(reset_required, bool, 0644);
+MODULE_PARM_DESC(reset_required, "override reset requirement (default: 1)");
+
/* probing devices from the AMBA bus */

static struct resource *get_amba_resource(struct vfio_platform_device *vdev,
@@ -68,6 +72,7 @@ static int vfio_amba_probe(struct amba_device *adev, const struct amba_id *id)
vdev->get_resource = get_amba_resource;
vdev->get_irq = get_amba_irq;
vdev->parent_module = THIS_MODULE;
+ vdev->reset_required = reset_required;

ret = vfio_platform_probe_common(vdev, &adev->dev);
if (ret) {
diff --git a/drivers/vfio/platform/vfio_platform.c b/drivers/vfio/platform/vfio_platform.c
index b1cc3a7..ef89146 100644
--- a/drivers/vfio/platform/vfio_platform.c
+++ b/drivers/vfio/platform/vfio_platform.c
@@ -23,6 +23,10 @@
#define DRIVER_AUTHOR "Antonios Motakis <a.motakis@virtualopensystems.com>"
#define DRIVER_DESC "VFIO for platform devices - User Level meta-driver"

+static bool reset_required = true;
+module_param(reset_required, bool, 0644);
+MODULE_PARM_DESC(reset_required, "override reset requirement (default: 1)");
+
/* probing devices from the linux platform bus */

static struct resource *get_platform_resource(struct vfio_platform_device *vdev,
@@ -66,6 +70,7 @@ static int vfio_platform_probe(struct platform_device *pdev)
vdev->get_resource = get_platform_resource;
vdev->get_irq = get_platform_irq;
vdev->parent_module = THIS_MODULE;
+ vdev->reset_required = reset_required;

ret = vfio_platform_probe_common(vdev, &pdev->dev);
if (ret)
diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index 0ea8c26..e87ceab 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -128,10 +128,10 @@ static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
return vdev->of_reset ? true : false;
}

-static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
+static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
{
if (vdev->acpihid)
- return;
+ return vfio_platform_acpi_has_reset(vdev) ? 0 : -ENOENT;

vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
&vdev->reset_module);
@@ -140,6 +140,8 @@ static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
&vdev->reset_module);
}
+
+ return vdev->of_reset ? 0 : -ENOENT;
}

static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
@@ -675,7 +677,13 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
return ret;
}

- vfio_platform_get_reset(vdev);
+ ret = vfio_platform_get_reset(vdev);
+ if (ret && vdev->reset_required) {
+ pr_err("vfio: no reset function found for device %s\n",
+ vdev->name);
+ iommu_group_put(group);
+ return ret;
+ }

mutex_init(&vdev->igate);

diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index ba9e4f8..68fbc00 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -50,6 +50,7 @@ struct vfio_platform_region {
};

struct vfio_platform_device {
+ bool reset_required;
struct vfio_platform_region *regions;
u32 num_regions;
struct vfio_platform_irq *irqs;
--
1.8.2.1