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Message-ID: <57431FA6.8060405@linaro.org>
Date: Mon, 23 May 2016 17:20:06 +0200
From: Eric Auger <eric.auger@...aro.org>
To: Sinan Kaya <okaya@...eaurora.org>, kvm@...r.kernel.org,
timur@...eaurora.org, cov@...eaurora.org, jcm@...hat.com
Cc: linux-acpi@...r.kernel.org, agross@...eaurora.org,
linux-arm-msm@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
Baptiste Reynal <b.reynal@...tualopensystems.com>,
Alex Williamson <alex.williamson@...hat.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH V5 6/6] vfio, platform: make reset driver a requirement by
default
Hi Sinan,
On 05/16/2016 04:13 AM, 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.
The commit message should describe the new module option.
You should also describe this is not just a matter of having a reset
function implemented & found somewhere but also a matter of having the
reset call to succeed. A reset failure now induce a failure on the first
open(). Shouldn't we handle this failure in a separate patch to make
this clearer?
>
> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> ---
> drivers/vfio/platform/vfio_amba.c | 5 +++++
> drivers/vfio/platform/vfio_platform.c | 5 +++++
> drivers/vfio/platform/vfio_platform_common.c | 18 ++++++++++++++----
> drivers/vfio/platform/vfio_platform_private.h | 1 +
> 4 files changed, 25 insertions(+), 4 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@...tualopensystems.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@...tualopensystems.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 095d5b7..89fb18f 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -121,10 +121,10 @@ 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 : -EINVAL;
-ENOENT instead?
>
> vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
> &vdev->reset_module);
> @@ -133,6 +133,8 @@ 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 : -EINVAL;
same
> }
>
> static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
> @@ -263,7 +265,9 @@ static int vfio_platform_open(void *device_data)
> if (ret)
> goto err_irq;
>
> - vfio_platform_call_reset(vdev);
> + ret = vfio_platform_call_reset(vdev);
> + if (ret && vdev->reset_required)
> + goto err_irq;
what do we do at release time in case the reset fails. You did not
change anything. Shouldn't we at least emit a warning to the user if the
reset becomes mandated (separate patch as evoked above)?
Thanks
Eric
> }
>
> vdev->refcnt++;
> @@ -669,7 +673,13 @@ 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;
>
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