On Wed, 25 Nov 2020 10:18:24 +0800
Colin Xu <colin.xu@xxxxxxxxx> wrote:
> Force specific device listed in params pm_restore_ids to follow
> device state save/restore as needs_pm_restore.
> Some device has NoSoftRst so will skip current state save/restore enabled
> by needs_pm_restore. However once the device experienced power state
> D3<->D0 transition, either by idle_d3 or the guest driver changes PM_CTL,
> the guest driver won't get correct devie state although the configure
> space doesn't change.
It sounds like you're describing a device that incorrectly exposes
NoSoftRst when there is in fact some sort of internal reset that
requires reprogramming config space. What device requires this? How
is a user to know when this option is required? It seems like this
would be better handled via a quirk in PCI core that sets a device flag
that the NoSoftRst value is incorrect for the specific affected
devices. Thanks,
Alex
>
> Cc: Swee Yee Fonn <swee.yee.fonn@xxxxxxxxx>
> Signed-off-by: Colin Xu <colin.xu@xxxxxxxxx>
> ---
> drivers/vfio/pci/vfio_pci.c | 66 ++++++++++++++++++++++++++++++++++++-
> 1 file changed, 65 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index e6190173482c..50a4141c9e1d 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -34,6 +34,15 @@
> #define DRIVER_AUTHOR "Alex Williamson <alex.williamson@xxxxxxxxxx>"
> #define DRIVER_DESC "VFIO PCI - User Level meta-driver"
>
> +#define VFIO_MAX_PM_DEV 32
> +struct vfio_pm_devs {
> + struct {
> + unsigned short vendor;
> + unsigned short device;
> + } ids[VFIO_MAX_PM_DEV];
> + u32 count;
> +};
> +
> static char ids[1024] __initdata;
> module_param_string(ids, ids, sizeof(ids), 0);
> MODULE_PARM_DESC(ids, "Initial PCI IDs to add to the vfio driver, format is \"vendor:device[:subvendor[:subdevice[:class[:class_mask]]]]\" and multiple comma separated entries can be specified");
> @@ -64,6 +73,10 @@ static bool disable_denylist;
> module_param(disable_denylist, bool, 0444);
> MODULE_PARM_DESC(disable_denylist, "Disable use of device denylist. Disabling the denylist allows binding to devices with known errata that may lead to exploitable stability or security issues when accessed by untrusted users.");
>
> +static char pm_restore_ids[1024] __initdata;
> +module_param_string(pm_restore_ids, pm_restore_ids, sizeof(pm_restore_ids), 0);
> +MODULE_PARM_DESC(pm_restore_ids, "comma separated device in format of \"vendor:device\"");
> +
> static inline bool vfio_vga_disabled(void)
> {
> #ifdef CONFIG_VFIO_PCI_VGA
> @@ -260,10 +273,50 @@ static bool vfio_pci_nointx(struct pci_dev *pdev)
> return false;
> }
>
> +static struct vfio_pm_devs pm_devs = {0};
> +static void __init vfio_pci_fill_pm_ids(void)
> +{
> + char *p, *id;
> + int idx = 0;
> +
> + /* no ids passed actually */
> + if (pm_restore_ids[0] == '\0')
> + return;
> +
> + /* add ids specified in the module parameter */
> + p = pm_restore_ids;
> + while ((id = strsep(&p, ","))) {
> + unsigned int vendor, device = PCI_ANY_ID;
> + int fields;
> +
> + if (!strlen(id))
> + continue;
> +
> + fields = sscanf(id, "%x:%x", &vendor, &device);
> +
> + if (fields != 2) {
> + pr_warn("invalid vendor:device string \"%s\"\n", id);
> + continue;
> + }
> +
> + if (idx < VFIO_MAX_PM_DEV) {
> + pm_devs.ids[idx].vendor = vendor;
> + pm_devs.ids[idx].device = device;
> + pm_devs.count++;
> + idx++;
> + pr_info("add [%04x:%04x] for needs_pm_restore\n",
> + vendor, device);
> + } else {
> + pr_warn("Exceed maximum %d, skip adding [%04x:%04x] for needs_pm_restore\n",
> + VFIO_MAX_PM_DEV, vendor, device);
> + }
> + }
> +}
> +
> static void vfio_pci_probe_power_state(struct vfio_pci_device *vdev)
> {
> struct pci_dev *pdev = vdev->pdev;
> - u16 pmcsr;
> + u16 pmcsr, idx;
>
> if (!pdev->pm_cap)
> return;
> @@ -271,6 +324,16 @@ static void vfio_pci_probe_power_state(struct vfio_pci_device *vdev)
> pci_read_config_word(pdev, pdev->pm_cap + PCI_PM_CTRL, &pmcsr);
>
> vdev->needs_pm_restore = !(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET);
> +
> + for (idx = 0; idx < pm_devs.count; idx++) {
> + if (vdev->pdev->vendor == pm_devs.ids[idx].vendor &&
> + vdev->pdev->device == pm_devs.ids[idx].device) {
> + vdev->needs_pm_restore = true;
> + pr_info("force [%04x:%04x] to needs_pm_restore\n",
> + vdev->pdev->vendor, vdev->pdev->device);
> + break;
> + }
> + }
> }
>
> /*
> @@ -2423,6 +2486,7 @@ static int __init vfio_pci_init(void)
> goto out_driver;
>
> vfio_pci_fill_ids();
> + vfio_pci_fill_pm_ids();
>
> if (disable_denylist)
> pr_warn("device denylist disabled.\n");
