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SubjectRe: [PATCH V7 7/9] vfio, platform: make reset driver a requirement by default
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Hi Sinan,

On 13/06/2016 06:26, Sinan Kaya wrote:
> 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>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> ---
> drivers/vfio/platform/vfio_amba.c | 5 +++++
> drivers/vfio/platform/vfio_platform.c | 5 +++++
> drivers/vfio/platform/vfio_platform_common.c | 22 +++++++++++++++-------
> drivers/vfio/platform/vfio_platform_private.h | 1 +
> 4 files changed, 26 insertions(+), 7 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..d84c399 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)
> @@ -670,16 +672,22 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> }
>
> ret = vfio_add_group_dev(dev, &vfio_platform_ops, vdev);
> - if (ret) {
> - iommu_group_put(group);
> - return ret;
> - }
> + if (ret)
> + goto out;
>
> - 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);
> + goto out;
> + }
Unfortunately this causes a crash when the reset module is not
available. You should do the vfio_add_group_dev at the end. Something
like below.

Best Regards

Eric

---
drivers/vfio/platform/vfio_platform_common.c | 26
++++++++++++--------------
1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform_common.c
b/drivers/vfio/platform/vfio_platform_common.c
index d84c399..0928f7d 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -664,6 +664,14 @@ int vfio_platform_probe_common(struct
vfio_platform_device *vdev,
return ret;

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

group = iommu_group_get(dev);
if (!group) {
@@ -672,22 +680,12 @@ int vfio_platform_probe_common(struct
vfio_platform_device *vdev,
}

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

return 0;
-out:
- iommu_group_put(group);
- return ret;
}
EXPORT_SYMBOL_GPL(vfio_platform_probe_common);


>
> mutex_init(&vdev->igate);
>
> return 0;
> +out:
> + iommu_group_put(group);
> + return ret;
> }
> EXPORT_SYMBOL_GPL(vfio_platform_probe_common);
>
> 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;
>

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