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Date: Fri, 31 Oct 2014 12:58:56 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: Antonios Motakis <a.motakis@...tualopensystems.com>
Cc: kvmarm@...ts.cs.columbia.edu, iommu@...ts.linux-foundation.org,
will.deacon@....com, tech@...tualopensystems.com,
christoffer.dall@...aro.org, eric.auger@...aro.org,
kim.phillips@...escale.com, marc.zyngier@....com,
"open list:VFIO DRIVER" <kvm@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v9 07/19] vfio/platform: return info for device memory
mapped IO regions
On Mon, 2014-10-27 at 19:07 +0100, Antonios Motakis wrote:
> This patch enables the IOCTLs VFIO_DEVICE_GET_REGION_INFO ioctl call,
> which allows the user to learn about the available MMIO resources of
> a device.
>
> Signed-off-by: Antonios Motakis <a.motakis@...tualopensystems.com>
> ---
> drivers/vfio/platform/vfio_platform_common.c | 110 +++++++++++++++++++++++++-
> drivers/vfio/platform/vfio_platform_private.h | 22 ++++++
> 2 files changed, 128 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index cb20526..82de752 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -27,17 +27,97 @@
>
> #include "vfio_platform_private.h"
>
> +static DEFINE_MUTEX(driver_lock);
> +
> +static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
> +{
> + int cnt = 0, i;
> +
> + while (vdev->get_resource(vdev, cnt))
> + cnt++;
> +
> + vdev->regions = kcalloc(cnt, sizeof(struct vfio_platform_region),
> + GFP_KERNEL);
> + if (!vdev->regions)
> + return -ENOMEM;
> +
> + for (i = 0; i < cnt; i++) {
> + struct resource *res =
> + vdev->get_resource(vdev, i);
> +
> + if (!res)
> + goto err;
> +
> + vdev->regions[i].addr = res->start;
> + vdev->regions[i].size = resource_size(res);
> + vdev->regions[i].flags = 0;
> +
> + switch (resource_type(res)) {
> + case IORESOURCE_MEM:
> + vdev->regions[i].type = VFIO_PLATFORM_REGION_TYPE_MMIO;
> + break;
> + case IORESOURCE_IO:
> + vdev->regions[i].type = VFIO_PLATFORM_REGION_TYPE_PIO;
> + break;
> + default:
> + goto err;
> + }
> + }
> +
> + vdev->num_regions = cnt;
> +
> + return 0;
> +err:
> + kfree(vdev->regions);
> + return -EINVAL;
> +}
> +
> +static void vfio_platform_regions_cleanup(struct vfio_platform_device *vdev)
> +{
> + vdev->num_regions = 0;
> + kfree(vdev->regions);
> +}
> +
> static void vfio_platform_release(void *device_data)
> {
> + struct vfio_platform_device *vdev = device_data;
> +
> + mutex_lock(&driver_lock);
> +
> + if (!(--vdev->refcnt)) {
> + vfio_platform_regions_cleanup(vdev);
> + }
> +
> + mutex_unlock(&driver_lock);
> +
> module_put(THIS_MODULE);
> }
>
> static int vfio_platform_open(void *device_data)
> {
> + struct vfio_platform_device *vdev = device_data;
> + int ret;
> +
> if (!try_module_get(THIS_MODULE))
> return -ENODEV;
>
> + mutex_lock(&driver_lock);
> +
> + if (!vdev->refcnt) {
> + ret = vfio_platform_regions_init(vdev);
> + if (ret)
> + goto err_reg;
> + }
> +
> + vdev->refcnt++;
> +
> + mutex_unlock(&driver_lock);
> return 0;
> +
> +err_reg:
> + mutex_unlock(&driver_lock);
> + module_put(THIS_MODULE);
> + return ret;
> }
>
> static long vfio_platform_ioctl(void *device_data,
> @@ -58,15 +138,33 @@ static long vfio_platform_ioctl(void *device_data,
> return -EINVAL;
>
> info.flags = vdev->flags;
> - info.num_regions = 0;
> + info.num_regions = vdev->num_regions;
> info.num_irqs = 0;
>
> return copy_to_user((void __user *)arg, &info, minsz);
>
> - } else if (cmd == VFIO_DEVICE_GET_REGION_INFO)
> - return -EINVAL;
> + } else if (cmd == VFIO_DEVICE_GET_REGION_INFO) {
> + struct vfio_region_info info;
> +
> + minsz = offsetofend(struct vfio_region_info, offset);
> +
> + if (copy_from_user(&info, (void __user *)arg, minsz))
> + return -EFAULT;
>
> - else if (cmd == VFIO_DEVICE_GET_IRQ_INFO)
> + if (info.argsz < minsz)
> + return -EINVAL;
> +
> + if (info.index >= vdev->num_regions)
> + return -EINVAL;
> +
> + /* map offset to the physical address */
> + info.offset = VFIO_PLATFORM_INDEX_TO_OFFSET(info.index);
> + info.size = vdev->regions[info.index].size;
> + info.flags = vdev->regions[info.index].flags;
> +
> + return copy_to_user((void __user *)arg, &info, minsz);
> +
> + } else if (cmd == VFIO_DEVICE_GET_IRQ_INFO)
> return -EINVAL;
>
> else if (cmd == VFIO_DEVICE_SET_IRQS)
> @@ -134,10 +232,14 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev)
> {
> struct vfio_platform_device *vdev;
>
> + mutex_lock(&driver_lock);
> +
> vdev = vfio_del_group_dev(dev);
> if (vdev)
> iommu_group_put(dev->iommu_group);
>
> + mutex_unlock(&driver_lock);
> +
This is the same deadlock that vfio-pci recently removed. Imagine that
you attempt to unbind an in-use device from vfio-platform,
vfio_del_group_dev() waits, holding the mutex, for the device to be
unused. vfio_platform_release() must acquire the mutex before it can
run. I don't think you need the mutex here. Thanks,
Alex
> return vdev;
> }
> EXPORT_SYMBOL_GPL(vfio_platform_remove_common);
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 062b92d..b24729f 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -15,7 +15,29 @@
> #ifndef VFIO_PLATFORM_PRIVATE_H
> #define VFIO_PLATFORM_PRIVATE_H
>
> +#define VFIO_PLATFORM_OFFSET_SHIFT 40
> +#define VFIO_PLATFORM_OFFSET_MASK (((u64)(1) << VFIO_PLATFORM_OFFSET_SHIFT) - 1)
> +
> +#define VFIO_PLATFORM_OFFSET_TO_INDEX(off) \
> + (off >> VFIO_PLATFORM_OFFSET_SHIFT)
> +
> +#define VFIO_PLATFORM_INDEX_TO_OFFSET(index) \
> + ((u64)(index) << VFIO_PLATFORM_OFFSET_SHIFT)
> +
> +struct vfio_platform_region {
> + u64 addr;
> + resource_size_t size;
> + u32 flags;
> + u32 type;
> +#define VFIO_PLATFORM_REGION_TYPE_MMIO 1
> +#define VFIO_PLATFORM_REGION_TYPE_PIO 2
> +};
> +
> struct vfio_platform_device {
> + struct vfio_platform_region *regions;
> + u32 num_regions;
> + int refcnt;
> +
> /*
> * These fields should be filled by the bus specific binder
> */
--
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