Re: [PATCH V4 vfio 9/9] vfio/virtio: Introduce a vfio driver over virtio devices

Yishai Hadas
2023-12-05T14:21:01Z

On 05/12/2023 1:32, Alex Williamson wrote:
> On Sun, 3 Dec 2023 16:54:41 +0200
> Yishai Hadas <yishaih@nvidia.com> wrote:
>
>> On 01/12/2023 0:10, Alex Williamson wrote:
>>> On Wed, 29 Nov 2023 16:37:46 +0200
>>> Yishai Hadas <yishaih@nvidia.com> wrote:
>>>
>>>> Introduce a vfio driver over virtio devices to support the legacy
>>>> interface functionality for VFs.
>>>>
>>>> Background, from the virtio spec [1].
>>>> --------------------------------------------------------------------
>>>> In some systems, there is a need to support a virtio legacy driver with
>>>> a device that does not directly support the legacy interface. In such
>>>> scenarios, a group owner device can provide the legacy interface
>>>> functionality for the group member devices. The driver of the owner
>>>> device can then access the legacy interface of a member device on behalf
>>>> of the legacy member device driver.
>>>>
>>>> For example, with the SR-IOV group type, group members (VFs) can not
>>>> present the legacy interface in an I/O BAR in BAR0 as expected by the
>>>> legacy pci driver. If the legacy driver is running inside a virtual
>>>> machine, the hypervisor executing the virtual machine can present a
>>>> virtual device with an I/O BAR in BAR0. The hypervisor intercepts the
>>>> legacy driver accesses to this I/O BAR and forwards them to the group
>>>> owner device (PF) using group administration commands.
>>>> --------------------------------------------------------------------
>>>>
>>>> Specifically, this driver adds support for a virtio-net VF to be exposed
>>>> as a transitional device to a guest driver and allows the legacy IO BAR
>>>> functionality on top.
>>>>
>>>> This allows a VM which uses a legacy virtio-net driver in the guest to
>>>> work transparently over a VF which its driver in the host is that new
>>>> driver.
>>>>
>>>> The driver can be extended easily to support some other types of virtio
>>>> devices (e.g virtio-blk), by adding in a few places the specific type
>>>> properties as was done for virtio-net.
>>>>
>>>> For now, only the virtio-net use case was tested and as such we introduce
>>>> the support only for such a device.
>>>>
>>>> Practically,
>>>> Upon probing a VF for a virtio-net device, in case its PF supports
>>>> legacy access over the virtio admin commands and the VF doesn't have BAR
>>>> 0, we set some specific 'vfio_device_ops' to be able to simulate in SW a
>>>> transitional device with I/O BAR in BAR 0.
>>>>
>>>> The existence of the simulated I/O bar is reported later on by
>>>> overwriting the VFIO_DEVICE_GET_REGION_INFO command and the device
>>>> exposes itself as a transitional device by overwriting some properties
>>>> upon reading its config space.
>>>>
>>>> Once we report the existence of I/O BAR as BAR 0 a legacy driver in the
>>>> guest may use it via read/write calls according to the virtio
>>>> specification.
>>>>
>>>> Any read/write towards the control parts of the BAR will be captured by
>>>> the new driver and will be translated into admin commands towards the
>>>> device.
>>>>
>>>> Any data path read/write access (i.e. virtio driver notifications) will
>>>> be forwarded to the physical BAR which its properties were supplied by
>>>> the admin command VIRTIO_ADMIN_CMD_LEGACY_NOTIFY_INFO upon the
>>>> probing/init flow.
>>>>
>>>> With that code in place a legacy driver in the guest has the look and
>>>> feel as if having a transitional device with legacy support for both its
>>>> control and data path flows.
>>>>
>>>> [1]
>>>> https://github.com/oasis-tcs/virtio-spec/commit/03c2d32e5093ca9f2a17797242fbef88efe94b8c
>>>>
>>>> Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
>>>> ---
>>>> MAINTAINERS | 7 +
>>>> drivers/vfio/pci/Kconfig | 2 +
>>>> drivers/vfio/pci/Makefile | 2 +
>>>> drivers/vfio/pci/virtio/Kconfig | 16 +
>>>> drivers/vfio/pci/virtio/Makefile | 4 +
>>>> drivers/vfio/pci/virtio/main.c | 554 +++++++++++++++++++++++++++++++
>>>> 6 files changed, 585 insertions(+)
>>>> create mode 100644 drivers/vfio/pci/virtio/Kconfig
>>>> create mode 100644 drivers/vfio/pci/virtio/Makefile
>>>> create mode 100644 drivers/vfio/pci/virtio/main.c
>>>>
>>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>>> index 012df8ccf34e..b246b769092d 100644
>>>> --- a/MAINTAINERS
>>>> +++ b/MAINTAINERS
>>>> @@ -22872,6 +22872,13 @@ L: kvm@vger.kernel.org
>>>> S: Maintained
>>>> F: drivers/vfio/pci/mlx5/
>>>>
>>>> +VFIO VIRTIO PCI DRIVER
>>>> +M: Yishai Hadas <yishaih@nvidia.com>
>>>> +L: kvm@vger.kernel.org
>>>> +L: virtualization@lists.linux-foundation.org
>>>> +S: Maintained
>>>> +F: drivers/vfio/pci/virtio
>>>> +
>>>> VFIO PCI DEVICE SPECIFIC DRIVERS
>>>> R: Jason Gunthorpe <jgg@nvidia.com>
>>>> R: Yishai Hadas <yishaih@nvidia.com>
>>>> diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
>>>> index 8125e5f37832..18c397df566d 100644
>>>> --- a/drivers/vfio/pci/Kconfig
>>>> +++ b/drivers/vfio/pci/Kconfig
>>>> @@ -65,4 +65,6 @@ source "drivers/vfio/pci/hisilicon/Kconfig"
>>>>
>>>> source "drivers/vfio/pci/pds/Kconfig"
>>>>
>>>> +source "drivers/vfio/pci/virtio/Kconfig"
>>>> +
>>>> endmenu
>>>> diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
>>>> index 45167be462d8..046139a4eca5 100644
>>>> --- a/drivers/vfio/pci/Makefile
>>>> +++ b/drivers/vfio/pci/Makefile
>>>> @@ -13,3 +13,5 @@ obj-$(CONFIG_MLX5_VFIO_PCI) += mlx5/
>>>> obj-$(CONFIG_HISI_ACC_VFIO_PCI) += hisilicon/
>>>>
>>>> obj-$(CONFIG_PDS_VFIO_PCI) += pds/
>>>> +
>>>> +obj-$(CONFIG_VIRTIO_VFIO_PCI) += virtio/
>>>> diff --git a/drivers/vfio/pci/virtio/Kconfig b/drivers/vfio/pci/virtio/Kconfig
>>>> new file mode 100644
>>>> index 000000000000..3a6707639220
>>>> --- /dev/null
>>>> +++ b/drivers/vfio/pci/virtio/Kconfig
>>>> @@ -0,0 +1,16 @@
>>>> +# SPDX-License-Identifier: GPL-2.0-only
>>>> +config VIRTIO_VFIO_PCI
>>>> + tristate "VFIO support for VIRTIO NET PCI devices"
>>>> + depends on VIRTIO_PCI
>>>> + select VFIO_PCI_CORE
>>>> + help
>>>> + This provides support for exposing VIRTIO NET VF devices which support
>>>> + legacy IO access, using the VFIO framework that can work with a legacy
>>>> + virtio driver in the guest.
>>>> + Based on PCIe spec, VFs do not support I/O Space; thus, VF BARs shall
>>>> + not indicate I/O Space.
>>>> + As of that this driver emulated I/O BAR in software to let a VF be
>>>> + seen as a transitional device in the guest and let it work with
>>>> + a legacy driver.
>>>> +
>>>> + If you don't know what to do here, say N.
>>>> diff --git a/drivers/vfio/pci/virtio/Makefile b/drivers/vfio/pci/virtio/Makefile
>>>> new file mode 100644
>>>> index 000000000000..2039b39fb723
>>>> --- /dev/null
>>>> +++ b/drivers/vfio/pci/virtio/Makefile
>>>> @@ -0,0 +1,4 @@
>>>> +# SPDX-License-Identifier: GPL-2.0-only
>>>> +obj-$(CONFIG_VIRTIO_VFIO_PCI) += virtio-vfio-pci.o
>>>> +virtio-vfio-pci-y := main.o
>>>> +
>>>> diff --git a/drivers/vfio/pci/virtio/main.c b/drivers/vfio/pci/virtio/main.c
>>>> new file mode 100644
>>>> index 000000000000..3ca19c891673
>>>> --- /dev/null
>>>> +++ b/drivers/vfio/pci/virtio/main.c
>>>> @@ -0,0 +1,554 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +/*
>>>> + * Copyright (c) 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved
>>>> + */
>>>> +
>>>> +#include <linux/device.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/mutex.h>
>>>> +#include <linux/pci.h>
>>>> +#include <linux/pm_runtime.h>
>>>> +#include <linux/types.h>
>>>> +#include <linux/uaccess.h>
>>>> +#include <linux/vfio.h>
>>>> +#include <linux/vfio_pci_core.h>
>>>> +#include <linux/virtio_pci.h>
>>>> +#include <linux/virtio_net.h>
>>>> +#include <linux/virtio_pci_admin.h>
>>>> +
>>>> +struct virtiovf_pci_core_device {
>>>> + struct vfio_pci_core_device core_device;
>>>> + u8 bar0_virtual_buf_size;
>>>
>>> Poor packing here, move it down with notify_bar.
>>
>> OK
>>
>>>
>>>> + u8 *bar0_virtual_buf;
>>>> + /* synchronize access to the virtual buf */
>>>> + struct mutex bar_mutex;
>>>> + void __iomem *notify_addr;
>>>> + u64 notify_offset;
>>>> + __le32 pci_base_addr_0;
>>>> + __le16 pci_cmd;
>>>> + u8 notify_bar;
>>>> +};
>>>> +
>>>> +static int
>>>> +virtiovf_issue_legacy_rw_cmd(struct virtiovf_pci_core_device *virtvdev,
>>>> + loff_t pos, char __user *buf,
>>>> + size_t count, bool read)
>>>> +{
>>>> + bool msix_enabled =
>>>> + (virtvdev->core_device.irq_type == VFIO_PCI_MSIX_IRQ_INDEX);
>>>
>>> This is racy, the irq_type could change, do we care or does that fall
>>> into poor driver behavior?
>>
>> This clearly falls into a poor driver behavior (e.g QEMU reads from a
>> given offset considering current irq_type once it changes it in parallel).
>
> Ok
>
>>>> + struct pci_dev *pdev = virtvdev->core_device.pdev;
>>>> + u8 *bar0_buf = virtvdev->bar0_virtual_buf;
>>>> + bool common;
>>>> + u8 offset;
>>>> + int ret;
>>>> +
>>>> + common = pos < VIRTIO_PCI_CONFIG_OFF(msix_enabled);
>>>
>>> I don't understand virtio, but this looks like it has the effect of the
>>> mac and status fields shifting in IO BAR depending on whether MSIX
>>> is enabled. Doesn't that give the user access to 4 bytes beyond the
>>> status field?
>>
>> It is accessing 4 bytes within the device io region that the device
>> would support.
>>
>> Is that how it's supposed to work or should we be
>>> dropping accesses to the 4-bytes MSIX support adds when not enabled?
>>
>> This is how it's supposed to work, accessing that area has no side effects.
>
> Ok
>
>>>> + /* offset within the relevant configuration area */
>>>> + offset = common ? pos : pos - VIRTIO_PCI_CONFIG_OFF(msix_enabled);
>>>> + mutex_lock(&virtvdev->bar_mutex);
>>>> + if (read) {
>>>> + if (common)
>>>> + ret = virtio_pci_admin_legacy_common_io_read(pdev, offset,
>>>> + count, bar0_buf + pos);
>>>> + else
>>>> + ret = virtio_pci_admin_legacy_device_io_read(pdev, offset,
>>>> + count, bar0_buf + pos);
>>>> + if (ret)
>>>> + goto out;
>>>> + if (copy_to_user(buf, bar0_buf + pos, count))
>>>> + ret = -EFAULT;
>>>> + } else {
>>>> + if (copy_from_user(bar0_buf + pos, buf, count)) {
>>>> + ret = -EFAULT;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + if (common)
>>>> + ret = virtio_pci_admin_legacy_common_io_write(pdev, offset,
>>>> + count, bar0_buf + pos);
>>>> + else
>>>> + ret = virtio_pci_admin_legacy_device_io_write(pdev, offset,
>>>> + count, bar0_buf + pos);
>>>> + }
>>>> +out:
>>>> + mutex_unlock(&virtvdev->bar_mutex);
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int
>>>> +translate_io_bar_to_mem_bar(struct virtiovf_pci_core_device *virtvdev,
>>>> + loff_t pos, char __user *buf,
>>>> + size_t count, bool read)
>>>> +{
>>>> + struct vfio_pci_core_device *core_device = &virtvdev->core_device;
>>>> + u16 queue_notify;
>>>> + int ret;
>>>> +
>>>> + if (pos + count > virtvdev->bar0_virtual_buf_size)
>>>> + return -EINVAL;
>>>> +
>>>> + switch (pos) {
>>>> + case VIRTIO_PCI_QUEUE_NOTIFY:
>>>> + if (count != sizeof(queue_notify))
>>>> + return -EINVAL;
>>>> + if (read) {
>>>> + ret = vfio_pci_ioread16(core_device, true, &queue_notify,
>>>> + virtvdev->notify_addr);
>>>> + if (ret)
>>>> + return ret;
>>>> + if (copy_to_user(buf, &queue_notify,
>>>> + sizeof(queue_notify)))
>>>> + return -EFAULT;
>>>> + } else {
>>>> + if (copy_from_user(&queue_notify, buf, count))
>>>> + return -EFAULT;
>>>> + ret = vfio_pci_iowrite16(core_device, true, queue_notify,
>>>> + virtvdev->notify_addr);
>>>> + }
>>>> + break;
>>>> + default:
>>>> + ret = virtiovf_issue_legacy_rw_cmd(virtvdev, pos, buf, count,
>>>> + read);
>>>> + }
>>>> +
>>>> + return ret ? ret : count;
>>>> +}
>>>> +
>>>> +static bool range_intersect_range(loff_t range1_start, size_t count1,
>>>> + loff_t range2_start, size_t count2,
>>>> + loff_t *start_offset,
>>>> + size_t *intersect_count,
>>>> + size_t *register_offset)
>>>> +{
>>>> + if (range1_start <= range2_start &&
>>>> + range1_start + count1 > range2_start) {
>>>> + *start_offset = range2_start - range1_start;
>>>> + *intersect_count = min_t(size_t, count2,
>>>> + range1_start + count1 - range2_start);
>>>> + *register_offset = 0;
>>>> + return true;
>>>> + }
>>>> +
>>>> + if (range1_start > range2_start &&
>>>> + range1_start < range2_start + count2) {
>>>> + *start_offset = 0;
>>>> + *intersect_count = min_t(size_t, count1,
>>>> + range2_start + count2 - range1_start);
>>>> + *register_offset = range1_start - range2_start;
>>>> + return true;
>>>> + }
>>>> +
>>>> + return false;
>>>> +}
>>>> +
>>>> +static ssize_t virtiovf_pci_read_config(struct vfio_device *core_vdev,
>>>> + char __user *buf, size_t count,
>>>> + loff_t *ppos)
>>>> +{
>>>> + struct virtiovf_pci_core_device *virtvdev = container_of(
>>>> + core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
>>>> + loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
>>>> + size_t register_offset;
>>>> + loff_t copy_offset;
>>>> + size_t copy_count;
>>>> + __le32 val32;
>>>> + __le16 val16;
>>>> + u8 val8;
>>>> + int ret;
>>>> +
>>>> + ret = vfio_pci_core_read(core_vdev, buf, count, ppos);
>>>> + if (ret < 0)
>>>> + return ret;
>>>> +
>>>> + if (range_intersect_range(pos, count, PCI_DEVICE_ID, sizeof(val16),
>>>> + &copy_offset, &copy_count, &register_offset)) {
>>>> + val16 = cpu_to_le16(VIRTIO_TRANS_ID_NET);
>>>> + if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset, copy_count))
>>>> + return -EFAULT;
>>>> + }
>>>> +
>>>> + if ((le16_to_cpu(virtvdev->pci_cmd) & PCI_COMMAND_IO) &&
>>>> + range_intersect_range(pos, count, PCI_COMMAND, sizeof(val16),
>>>> + &copy_offset, &copy_count, &register_offset)) {
>>>> + if (copy_from_user((void *)&val16 + register_offset, buf + copy_offset,
>>>> + copy_count))
>>>> + return -EFAULT;
>>>> + val16 |= cpu_to_le16(PCI_COMMAND_IO);
>>>> + if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset,
>>>> + copy_count))
>>>> + return -EFAULT;
>>>> + }
>>>
>>> Seems like COMMAND_IO survives across reset, pci_cmd is only ever
>>> modified by user writes.
>>
>> I see.
>>
>> If so, we may need to add a callback for pci_error_handlers.reset_done
>> to set it back to zero.
>>
>> I'll add as part of V5.
>>
>>>
>>> I also don't see that we honor COMMAND_IO for accesses. Shouldn't reads
>>> return -1 and writes get dropped if COMMAND_IO is cleared?
>>
>> You mean that if the 'COMMAND_IO' bit was not set, we should not allow
>> read/write towards the IO bar, right ?
>
> Yes
>
>> If so, I would expect to return -EFAULT from
>> translate_io_bar_to_mem_bar() in that case for both read/write and let
>> the upper SW layers (e.g. QEMU) to consider that as '-1 (0xfff) data'
>> for read and ignore it upon writes.
>>
>> Agree ?
>
> vfio_pci_io{read,write}##size returns -EIO for MMIO accesses when
> COMMAND_MEMORY is disabled, might as well follow that precedent rather
> than -EFAULT.
>

Makes sense, I'll return -EIO in that case.

> Note that this will be a little different from a physical IO BAR
> though. It's not been necessary to check COMMAND_IO for such accesses
> since IO space will soft fail and we can therefore let the IO system
> fabricate the read value and drop writes. QEMU might be overly verbose
> getting an errno, but it should do the write thing relative to the VM.
>
>>>> +
>>>> + if (range_intersect_range(pos, count, PCI_REVISION_ID, sizeof(val8),
>>>> + &copy_offset, &copy_count, &register_offset)) {
>>>> + /* Transional needs to have revision 0 */
>>>> + val8 = 0;
>>>> + if (copy_to_user(buf + copy_offset, &val8, copy_count))
>>>> + return -EFAULT;
>>>> + }
>>>> +
>>>> + if (range_intersect_range(pos, count, PCI_BASE_ADDRESS_0, sizeof(val32),
>>>> + &copy_offset, &copy_count, &register_offset)) {
>>>> + u8 log_bar_size = ilog2(roundup_pow_of_two(virtvdev->bar0_virtual_buf_size));
>>>> + u32 mask_size = ~((BIT(log_bar_size) - 1));
>>>
>>> bar0_virtual_buf_size already needs to be a power-of-2, the size we
>>> report here needs to match the REGION_INFO size, so we should enforce
>>> the size in virtio_vf_pci_init_device(). I think it's 32bytes, so
>>> we're actually good on the size,
>>
>> Yes, this is 32 bytes which is power of 2 and we should be fine as you
>> wrote.
>>
>> Do you suggest to enforce the calculated size explicitly as part of
>> virtio_vf_pci_init_device() to be power of 2 with some check ?
>
> Yes, I'd go ahead and do the roundup there or maybe assert that it's a
> power of 2, potentially even a build bug check since it's sized based
> on uAPI structures. Essentially just something to prove we're not
> creating a bogus size and reinforce that we can do things like below
> without all the unnecessary operations above. Thanks,

OK, the below will do the work as you suggested.
BUILD_BUG_ON(!is_power_of_2(virtvdev->bar0_virtual_buf_size));

Thanks,
Yishai

>
> Alex
>
>> but the above makes no sense, ie.
>>> rounding a value that's already a power-of-2 to a power-of-2, getting
>>> the log2 size, shifting that back into the size we started with to get
>>> a mask... why isn't it just:
>>>
>>> u32 bar_mask = ~(virtvdev->bar0_virtual_buf_size - 1);
>>> ?
>>
>> Yes, it makes sense, will use that formula as part of V5.
>>
>>>
>>>
>>>> + u32 pci_base_addr_0 = le32_to_cpu(virtvdev->pci_base_addr_0);
>>>> +
>>>> + val32 = cpu_to_le32((pci_base_addr_0 & mask_size) | PCI_BASE_ADDRESS_SPACE_IO);
>>>
>>> Looks like what I suggested to Ankit :)
>>>
>>> Per our prior variant driver agreement, we're going to need to enlist
>>> another reviewer as well. Thanks,
>>>
>>
>> OK
>>
>> Hopefully V5 will address the latest notes from you and be ready as a
>> candidate for other people to review.
>>
>> Thanks,
>> Yishai
>>
>>> Alex
>>>
>>>> + if (copy_to_user(buf + copy_offset, (void *)&val32 + register_offset, copy_count))
>>>> + return -EFAULT;
>>>> + }
>>>> +
>>>> + if (range_intersect_range(pos, count, PCI_SUBSYSTEM_ID, sizeof(val16),
>>>> + &copy_offset, &copy_count, &register_offset)) {
>>>> + /*
>>>> + * Transitional devices use the PCI subsystem device id as
>>>> + * virtio device id, same as legacy driver always did.
>>>> + */
>>>> + val16 = cpu_to_le16(VIRTIO_ID_NET);
>>>> + if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset,
>>>> + copy_count))
>>>> + return -EFAULT;
>>>> + }
>>>> +
>>>> + if (range_intersect_range(pos, count, PCI_SUBSYSTEM_VENDOR_ID, sizeof(val16),
>>>> + &copy_offset, &copy_count, &register_offset)) {
>>>> + val16 = cpu_to_le16(PCI_VENDOR_ID_REDHAT_QUMRANET);
>>>> + if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset,
>>>> + copy_count))
>>>> + return -EFAULT;
>>>> + }
>>>> +
>>>> + return count;
>>>> +}
>>>> +
>>>> +static ssize_t
>>>> +virtiovf_pci_core_read(struct vfio_device *core_vdev, char __user *buf,
>>>> + size_t count, loff_t *ppos)
>>>> +{
>>>> + struct virtiovf_pci_core_device *virtvdev = container_of(
>>>> + core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
>>>> + struct pci_dev *pdev = virtvdev->core_device.pdev;
>>>> + unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
>>>> + loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
>>>> + int ret;
>>>> +
>>>> + if (!count)
>>>> + return 0;
>>>> +
>>>> + if (index == VFIO_PCI_CONFIG_REGION_INDEX)
>>>> + return virtiovf_pci_read_config(core_vdev, buf, count, ppos);
>>>> +
>>>> + if (index != VFIO_PCI_BAR0_REGION_INDEX)
>>>> + return vfio_pci_core_read(core_vdev, buf, count, ppos);
>>>> +
>>>> + ret = pm_runtime_resume_and_get(&pdev->dev);
>>>> + if (ret) {
>>>> + pci_info_ratelimited(pdev, "runtime resume failed %d\n",
>>>> + ret);
>>>> + return -EIO;
>>>> + }
>>>> +
>>>> + ret = translate_io_bar_to_mem_bar(virtvdev, pos, buf, count, true);
>>>> + pm_runtime_put(&pdev->dev);
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static ssize_t
>>>> +virtiovf_pci_core_write(struct vfio_device *core_vdev, const char __user *buf,
>>>> + size_t count, loff_t *ppos)
>>>> +{
>>>> + struct virtiovf_pci_core_device *virtvdev = container_of(
>>>> + core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
>>>> + struct pci_dev *pdev = virtvdev->core_device.pdev;
>>>> + unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
>>>> + loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
>>>> + int ret;
>>>> +
>>>> + if (!count)
>>>> + return 0;
>>>> +
>>>> + if (index == VFIO_PCI_CONFIG_REGION_INDEX) {
>>>> + size_t register_offset;
>>>> + loff_t copy_offset;
>>>> + size_t copy_count;
>>>> +
>>>> + if (range_intersect_range(pos, count, PCI_COMMAND, sizeof(virtvdev->pci_cmd),
>>>> + &copy_offset, &copy_count,
>>>> + &register_offset)) {
>>>> + if (copy_from_user((void *)&virtvdev->pci_cmd + register_offset,
>>>> + buf + copy_offset,
>>>> + copy_count))
>>>> + return -EFAULT;
>>>> + }
>>>> +
>>>> + if (range_intersect_range(pos, count, PCI_BASE_ADDRESS_0,
>>>> + sizeof(virtvdev->pci_base_addr_0),
>>>> + &copy_offset, &copy_count,
>>>> + &register_offset)) {
>>>> + if (copy_from_user((void *)&virtvdev->pci_base_addr_0 + register_offset,
>>>> + buf + copy_offset,
>>>> + copy_count))
>>>> + return -EFAULT;
>>>> + }
>>>> + }
>>>> +
>>>> + if (index != VFIO_PCI_BAR0_REGION_INDEX)
>>>> + return vfio_pci_core_write(core_vdev, buf, count, ppos);
>>>> +
>>>> + ret = pm_runtime_resume_and_get(&pdev->dev);
>>>> + if (ret) {
>>>> + pci_info_ratelimited(pdev, "runtime resume failed %d\n", ret);
>>>> + return -EIO;
>>>> + }
>>>> +
>>>> + ret = translate_io_bar_to_mem_bar(virtvdev, pos, (char __user *)buf, count, false);
>>>> + pm_runtime_put(&pdev->dev);
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int
>>>> +virtiovf_pci_ioctl_get_region_info(struct vfio_device *core_vdev,
>>>> + unsigned int cmd, unsigned long arg)
>>>> +{
>>>> + struct virtiovf_pci_core_device *virtvdev = container_of(
>>>> + core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
>>>> + unsigned long minsz = offsetofend(struct vfio_region_info, offset);
>>>> + void __user *uarg = (void __user *)arg;
>>>> + struct vfio_region_info info = {};
>>>> +
>>>> + if (copy_from_user(&info, uarg, minsz))
>>>> + return -EFAULT;
>>>> +
>>>> + if (info.argsz < minsz)
>>>> + return -EINVAL;
>>>> +
>>>> + switch (info.index) {
>>>> + case VFIO_PCI_BAR0_REGION_INDEX:
>>>> + info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
>>>> + info.size = virtvdev->bar0_virtual_buf_size;
>>>> + info.flags = VFIO_REGION_INFO_FLAG_READ |
>>>> + VFIO_REGION_INFO_FLAG_WRITE;
>>>> + return copy_to_user(uarg, &info, minsz) ? -EFAULT : 0;
>>>> + default:
>>>> + return vfio_pci_core_ioctl(core_vdev, cmd, arg);
>>>> + }
>>>> +}
>>>> +
>>>> +static long
>>>> +virtiovf_vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
>>>> + unsigned long arg)
>>>> +{
>>>> + switch (cmd) {
>>>> + case VFIO_DEVICE_GET_REGION_INFO:
>>>> + return virtiovf_pci_ioctl_get_region_info(core_vdev, cmd, arg);
>>>> + default:
>>>> + return vfio_pci_core_ioctl(core_vdev, cmd, arg);
>>>> + }
>>>> +}
>>>> +
>>>> +static int
>>>> +virtiovf_set_notify_addr(struct virtiovf_pci_core_device *virtvdev)
>>>> +{
>>>> + struct vfio_pci_core_device *core_device = &virtvdev->core_device;
>>>> + int ret;
>>>> +
>>>> + /*
>>>> + * Setup the BAR where the 'notify' exists to be used by vfio as well
>>>> + * This will let us mmap it only once and use it when needed.
>>>> + */
>>>> + ret = vfio_pci_core_setup_barmap(core_device,
>>>> + virtvdev->notify_bar);
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + virtvdev->notify_addr = core_device->barmap[virtvdev->notify_bar] +
>>>> + virtvdev->notify_offset;
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int virtiovf_pci_open_device(struct vfio_device *core_vdev)
>>>> +{
>>>> + struct virtiovf_pci_core_device *virtvdev = container_of(
>>>> + core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
>>>> + struct vfio_pci_core_device *vdev = &virtvdev->core_device;
>>>> + int ret;
>>>> +
>>>> + ret = vfio_pci_core_enable(vdev);
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + if (virtvdev->bar0_virtual_buf) {
>>>> + /*
>>>> + * Upon close_device() the vfio_pci_core_disable() is called
>>>> + * and will close all the previous mmaps, so it seems that the
>>>> + * valid life cycle for the 'notify' addr is per open/close.
>>>> + */
>>>> + ret = virtiovf_set_notify_addr(virtvdev);
>>>> + if (ret) {
>>>> + vfio_pci_core_disable(vdev);
>>>> + return ret;
>>>> + }
>>>> + }
>>>> +
>>>> + vfio_pci_core_finish_enable(vdev);
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int virtiovf_get_device_config_size(unsigned short device)
>>>> +{
>>>> + /* Network card */
>>>> + return offsetofend(struct virtio_net_config, status);
>>>> +}
>>>> +
>>>> +static int virtiovf_read_notify_info(struct virtiovf_pci_core_device *virtvdev)
>>>> +{
>>>> + u64 offset;
>>>> + int ret;
>>>> + u8 bar;
>>>> +
>>>> + ret = virtio_pci_admin_legacy_io_notify_info(virtvdev->core_device.pdev,
>>>> + VIRTIO_ADMIN_CMD_NOTIFY_INFO_FLAGS_OWNER_MEM,
>>>> + &bar, &offset);
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + virtvdev->notify_bar = bar;
>>>> + virtvdev->notify_offset = offset;
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int virtiovf_pci_init_device(struct vfio_device *core_vdev)
>>>> +{
>>>> + struct virtiovf_pci_core_device *virtvdev = container_of(
>>>> + core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
>>>> + struct pci_dev *pdev;
>>>> + int ret;
>>>> +
>>>> + ret = vfio_pci_core_init_dev(core_vdev);
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + pdev = virtvdev->core_device.pdev;
>>>> + ret = virtiovf_read_notify_info(virtvdev);
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + /* Being ready with a buffer that supports MSIX */
>>>> + virtvdev->bar0_virtual_buf_size = VIRTIO_PCI_CONFIG_OFF(true) +
>>>> + virtiovf_get_device_config_size(pdev->device);
>>>> + virtvdev->bar0_virtual_buf = kzalloc(virtvdev->bar0_virtual_buf_size,
>>>> + GFP_KERNEL);
>>>> + if (!virtvdev->bar0_virtual_buf)
>>>> + return -ENOMEM;
>>>> + mutex_init(&virtvdev->bar_mutex);
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static void virtiovf_pci_core_release_dev(struct vfio_device *core_vdev)
>>>> +{
>>>> + struct virtiovf_pci_core_device *virtvdev = container_of(
>>>> + core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
>>>> +
>>>> + kfree(virtvdev->bar0_virtual_buf);
>>>> + vfio_pci_core_release_dev(core_vdev);
>>>> +}
>>>> +
>>>> +static const struct vfio_device_ops virtiovf_vfio_pci_tran_ops = {
>>>> + .name = "virtio-vfio-pci-trans",
>>>> + .init = virtiovf_pci_init_device,
>>>> + .release = virtiovf_pci_core_release_dev,
>>>> + .open_device = virtiovf_pci_open_device,
>>>> + .close_device = vfio_pci_core_close_device,
>>>> + .ioctl = virtiovf_vfio_pci_core_ioctl,
>>>> + .read = virtiovf_pci_core_read,
>>>> + .write = virtiovf_pci_core_write,
>>>> + .mmap = vfio_pci_core_mmap,
>>>> + .request = vfio_pci_core_request,
>>>> + .match = vfio_pci_core_match,
>>>> + .bind_iommufd = vfio_iommufd_physical_bind,
>>>> + .unbind_iommufd = vfio_iommufd_physical_unbind,
>>>> + .attach_ioas = vfio_iommufd_physical_attach_ioas,
>>>> +};
>>>> +
>>>> +static const struct vfio_device_ops virtiovf_vfio_pci_ops = {
>>>> + .name = "virtio-vfio-pci",
>>>> + .init = vfio_pci_core_init_dev,
>>>> + .release = vfio_pci_core_release_dev,
>>>> + .open_device = virtiovf_pci_open_device,
>>>> + .close_device = vfio_pci_core_close_device,
>>>> + .ioctl = vfio_pci_core_ioctl,
>>>> + .device_feature = vfio_pci_core_ioctl_feature,
>>>> + .read = vfio_pci_core_read,
>>>> + .write = vfio_pci_core_write,
>>>> + .mmap = vfio_pci_core_mmap,
>>>> + .request = vfio_pci_core_request,
>>>> + .match = vfio_pci_core_match,
>>>> + .bind_iommufd = vfio_iommufd_physical_bind,
>>>> + .unbind_iommufd = vfio_iommufd_physical_unbind,
>>>> + .attach_ioas = vfio_iommufd_physical_attach_ioas,
>>>> +};
>>>> +
>>>> +static bool virtiovf_bar0_exists(struct pci_dev *pdev)
>>>> +{
>>>> + struct resource *res = pdev->resource;
>>>> +
>>>> + return res->flags ? true : false;
>>>> +}
>>>> +
>>>> +static int virtiovf_pci_probe(struct pci_dev *pdev,
>>>> + const struct pci_device_id *id)
>>>> +{
>>>> + const struct vfio_device_ops *ops = &virtiovf_vfio_pci_ops;
>>>> + struct virtiovf_pci_core_device *virtvdev;
>>>> + int ret;
>>>> +
>>>> + if (pdev->is_virtfn && virtio_pci_admin_has_legacy_io(pdev) &&
>>>> + !virtiovf_bar0_exists(pdev))
>>>> + ops = &virtiovf_vfio_pci_tran_ops;
>>>> +
>>>> + virtvdev = vfio_alloc_device(virtiovf_pci_core_device, core_device.vdev,
>>>> + &pdev->dev, ops);
>>>> + if (IS_ERR(virtvdev))
>>>> + return PTR_ERR(virtvdev);
>>>> +
>>>> + dev_set_drvdata(&pdev->dev, &virtvdev->core_device);
>>>> + ret = vfio_pci_core_register_device(&virtvdev->core_device);
>>>> + if (ret)
>>>> + goto out;
>>>> + return 0;
>>>> +out:
>>>> + vfio_put_device(&virtvdev->core_device.vdev);
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static void virtiovf_pci_remove(struct pci_dev *pdev)
>>>> +{
>>>> + struct virtiovf_pci_core_device *virtvdev = dev_get_drvdata(&pdev->dev);
>>>> +
>>>> + vfio_pci_core_unregister_device(&virtvdev->core_device);
>>>> + vfio_put_device(&virtvdev->core_device.vdev);
>>>> +}
>>>> +
>>>> +static const struct pci_device_id virtiovf_pci_table[] = {
>>>> + /* Only virtio-net is supported/tested so far */
>>>> + { PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_REDHAT_QUMRANET, 0x1041) },
>>>> + {}
>>>> +};
>>>> +
>>>> +MODULE_DEVICE_TABLE(pci, virtiovf_pci_table);
>>>> +
>>>> +static struct pci_driver virtiovf_pci_driver = {
>>>> + .name = KBUILD_MODNAME,
>>>> + .id_table = virtiovf_pci_table,
>>>> + .probe = virtiovf_pci_probe,
>>>> + .remove = virtiovf_pci_remove,
>>>> + .err_handler = &vfio_pci_core_err_handlers,
>>>> + .driver_managed_dma = true,
>>>> +};
>>>> +
>>>> +module_pci_driver(virtiovf_pci_driver);
>>>> +
>>>> +MODULE_LICENSE("GPL");
>>>> +MODULE_AUTHOR("Yishai Hadas <yishaih@nvidia.com>");
>>>> +MODULE_DESCRIPTION(
>>>> + "VIRTIO VFIO PCI - User Level meta-driver for VIRTIO NET devices");
>>>
>>
>