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Message-ID: <CAG8rG2wNREAurf-gYD=3RTE9kWO5=gOvtydxQzvrn9TnxMj_1Q@mail.gmail.com>
Date: Wed, 5 Nov 2014 10:50:46 +0100
From: Antonios Motakis <a.motakis@...tualopensystems.com>
To: Alex Williamson <alex.williamson@...hat.com>
Cc: kvm-arm <kvmarm@...ts.cs.columbia.edu>,
Linux IOMMU <iommu@...ts.linux-foundation.org>,
Will Deacon <will.deacon@....com>,
VirtualOpenSystems Technical Team <tech@...tualopensystems.com>,
Christoffer Dall <christoffer.dall@...aro.org>,
Eric Auger <eric.auger@...aro.org>,
Kim Phillips <kim.phillips@...escale.com>,
Marc Zyngier <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 Fri, Oct 31, 2014 at 7:58 PM, Alex Williamson
<alex.williamson@...hat.com> wrote:
> 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,
Fair enough, no mutex for _release then.
>
> 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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