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Date: Wed, 22 Oct 2014 15:54:46 +0200
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 v8 07/18] vfio/platform: return info for device memory
mapped IO regions
On Tue, Oct 21, 2014 at 6:34 PM, Alex Williamson
<alex.williamson@...hat.com> wrote:
> On Mon, 2014-10-13 at 15:10 +0200, 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 | 93 +++++++++++++++++++++++++--
>> drivers/vfio/platform/vfio_platform_private.h | 22 +++++++
>> 2 files changed, 111 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
>> index 1e4073f..8a7e474 100644
>> --- a/drivers/vfio/platform/vfio_platform_common.c
>> +++ b/drivers/vfio/platform/vfio_platform_common.c
>> @@ -27,17 +27,84 @@
>>
>> #include "vfio_platform_private.h"
>>
>> +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;
>
> Ok, we have support for PIO in platform now (thanks!), does the user
> know what type of region they're dealing with? Do they care? For PCI
> the user tests the PCI BAR in config space to determine which type it
> is. I'm guessing that platform would do something similar against the
> device tree or ACPI, right?
Maybe is worthwhile to add an explicit flag in
VFIO_DEVICE_GET_REGION_INFO for PIO regions. For platform devices I
don't know if we can always rely on DT or ACPI info to be available.
For VFIO PCI the BAR is always implemented, and while I have proposed
an RFC to return DT information, I don't think we can assume how a
device is described in the host, whether DT, ACPI, or dark magic.
>
>> + 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;
>> +
>> + if (atomic_dec_and_test(&vdev->refcnt))
>> + vfio_platform_regions_cleanup(vdev);
>> +
>> 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;
>>
>> + if (atomic_inc_return(&vdev->refcnt) == 1) {
>> + ret = vfio_platform_regions_init(vdev);
>> + if (ret)
>> + goto err_reg;
>> + }
>> +
>> return 0;
>> +
>> +err_reg:
>> + module_put(THIS_MODULE);
>> + return ret;
>
> Note that if vfio_platform_regions_init() fails then your refcnt is
> wrong. We switched to a mutex in vfio-pci to avoid this. See
> 61d792562b53.
Ack.
>
>> }
>>
>> static long vfio_platform_ioctl(void *device_data,
>> @@ -58,15 +125,33 @@ 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;
>> +
>> + 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)
>> + } else if (cmd == VFIO_DEVICE_GET_IRQ_INFO)
>> return -EINVAL;
>>
>> else if (cmd == VFIO_DEVICE_SET_IRQS)
>> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
>> index ef76737..2a06035 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;
>> + atomic_t refcnt;
>> +
>> /*
>> * These fields should be filled by the bus driver at binding time
>> */
>
>
>
--
Antonios Motakis
Virtual Open Systems
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