Re: [PATCH v2 02/13] vfio_pci: refine user config reference in vfio-pci module

Alex Williamson
2019-09-26T02:36:15Z

On Thu, 5 Sep 2019 15:59:19 +0800
Liu Yi L <yi.l.liu@intel.com> wrote:

> This patch adds three fields in struct vfio_pci_device to pass the user
> configs of vfio-pci module to some functions which could be common in
> future usage.
>
> Cc: Kevin Tian <kevin.tian@intel.com>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> ---
> drivers/vfio/pci/vfio_pci.c | 24 +++++++++++++++---------
> drivers/vfio/pci/vfio_pci_private.h | 9 +++++++--
> 2 files changed, 22 insertions(+), 11 deletions(-)

A subtle behavioral difference here is that disable_idle_d3 and
nointxmask are runtime modifiable parameters, if the value is changed
in sysfs the device will adopt the new behavior on its next
transition. After this patch, each device operates in the mode defined
at the time it was probed. Should we maybe refresh the value at key
points, like the user opening or releasing the device so that it tracks
the module parameter? I think we could defend not changing the
behavior of a device while it's in use by a user. Otherwise we might
want to make the module parameter read-only to avoid the
inconsistency.

>
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 38271df..fed2687 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -69,7 +69,8 @@ static unsigned int vfio_pci_set_vga_decode(void *opaque, bool single_vga)
> unsigned char max_busnr;
> unsigned int decodes;
>
> - if (single_vga || !vfio_vga_disabled() || pci_is_root_bus(pdev->bus))
> + if (single_vga || !vfio_vga_disabled(vdev) ||
> + pci_is_root_bus(pdev->bus))
> return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM |
> VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
>
> @@ -273,7 +274,7 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
> if (!vdev->pci_saved_state)
> pci_dbg(pdev, "%s: Couldn't store saved state\n", __func__);
>
> - if (likely(!nointxmask)) {
> + if (likely(!vdev->nointxmask)) {
> if (vfio_pci_nointx(pdev)) {
> pci_info(pdev, "Masking broken INTx support\n");
> vdev->nointx = true;
> @@ -310,7 +311,7 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
> } else
> vdev->msix_bar = 0xFF;
>
> - if (!vfio_vga_disabled() && vfio_pci_is_vga(pdev))
> + if (!vfio_vga_disabled(vdev) && vfio_pci_is_vga(pdev))
> vdev->has_vga = true;
>
>
> @@ -436,7 +437,7 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
>
> vfio_pci_try_bus_reset(vdev);
>
> - if (!disable_idle_d3)
> + if (!vdev->disable_idle_d3)
> vfio_pci_set_power_state(vdev, PCI_D3hot);
> }
>
> @@ -1304,6 +1305,11 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> spin_lock_init(&vdev->irqlock);
> mutex_init(&vdev->ioeventfds_lock);
> INIT_LIST_HEAD(&vdev->ioeventfds_list);
> + vdev->nointxmask = nointxmask;
> +#ifdef CONFIG_VFIO_PCI_VGA
> + vdev->disable_vga = disable_vga;
> +#endif
> + vdev->disable_idle_d3 = disable_idle_d3;
>
> ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
> if (ret) {
> @@ -1328,7 +1334,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>
> vfio_pci_probe_power_state(vdev);
>
> - if (!disable_idle_d3) {
> + if (!vdev->disable_idle_d3) {
> /*
> * pci-core sets the device power state to an unknown value at
> * bootup and after being removed from a driver. The only
> @@ -1359,7 +1365,7 @@ static void vfio_pci_remove(struct pci_dev *pdev)
> kfree(vdev->region);
> mutex_destroy(&vdev->ioeventfds_lock);
>
> - if (!disable_idle_d3)
> + if (!vdev->disable_idle_d3)
> vfio_pci_set_power_state(vdev, PCI_D0);
>
> kfree(vdev->pm_save);
> @@ -1594,7 +1600,7 @@ static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev)
> if (!ret) {
> tmp->needs_reset = false;
>
> - if (tmp != vdev && !disable_idle_d3)
> + if (tmp != vdev && !tmp->disable_idle_d3)
> vfio_pci_set_power_state(tmp, PCI_D3hot);
> }
>
> @@ -1610,7 +1616,7 @@ static void __exit vfio_pci_cleanup(void)
> vfio_pci_uninit_perm_bits();
> }
>
> -static void __init vfio_pci_fill_ids(void)
> +static void __init vfio_pci_fill_ids(char *ids)
> {
> char *p, *id;
> int rc;
> @@ -1665,7 +1671,7 @@ static int __init vfio_pci_init(void)
> if (ret)
> goto out_driver;
>
> - vfio_pci_fill_ids();
> + vfio_pci_fill_ids(&ids[0]);

Or just 'ids'. Thanks,

Alex

>
> return 0;
>
> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> index f12d92c..68521d2 100644
> --- a/drivers/vfio/pci/vfio_pci_private.h
> +++ b/drivers/vfio/pci/vfio_pci_private.h
> @@ -122,6 +122,11 @@ struct vfio_pci_device {
> struct list_head dummy_resources_list;
> struct mutex ioeventfds_lock;
> struct list_head ioeventfds_list;
> + bool nointxmask;
> +#ifdef CONFIG_VFIO_PCI_VGA
> + bool disable_vga;
> +#endif
> + bool disable_idle_d3;
> };
>
> #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)
> @@ -135,10 +140,10 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev)
> return (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA;
> }
>
> -static inline bool vfio_vga_disabled(void)
> +static inline bool vfio_vga_disabled(struct vfio_pci_device *vdev)
> {
> #ifdef CONFIG_VFIO_PCI_VGA
> - return disable_vga;
> + return vdev->disable_vga;
> #else
> return true;
> #endif