[+cc Hui]
On Sat, Jul 12, 2025 at 07:30:28PM +0800, Weili Qian wrote:
> Prior to commit d591f6804e7e ("PCI: Wait for device readiness with
> Configuration RRS"), pci_dev_wait() polls PCI_COMMAND register until
> its value is not ~0(i.e., PCI_ERROR_RESPONSE). After d591f6804e7e,
> if the Configuration Request Retry Status Software Visibility (RRS SV)
> is enabled, pci_dev_wait() polls PCI_VENDOR_ID register until its value
> is not the reserved Vendor ID value 0x0001.
>
> On Kunpeng accelerator devices, RRS SV is enabled. However,
> when the virtual function's FLR (Function Level Reset) is not
> ready, the pci_dev_wait() reads the PCI_VENDOR_ID register and gets
> the value 0xffff instead of 0x0001. It then incorrectly assumes this
> is a valid Vendor ID and concludes the device is ready, returning
> successfully. In reality, the function may not be fully ready, leading
> to the device becoming unavailable.
>
> A 100ms wait period is already implemented before calling pci_dev_wait().
> In most cases, FLR completes within 100ms. However, to eliminate the
> risk of function being unavailable due to an incomplete FLR, a
> device-specific reset is added. After pcie_flr(), the function continues
> to poll PCI_COMMAND register until its value is no longer ~0.
As far as I can tell, there's nothing specific to Kungpeng devices
here. We've seen a similar issue with Intel NVMe devices [1], and I
don't want a whole mess of quirks and device-specific reset methods.
We need some sort of generic solution for this. My understanding was
that if devices are not ready 100ms after a reset, they are required
to respond with RRS. Maybe these devices are defective. Or maybe my
understanding is incorrect. Either way, I think we should at least
check for a PCIe error before assuming that 0xffff is a valid
response.
[1] https://lore.kernel.org/linux-pci/20250611101442.387378-1-hui.wang@xxxxxxxxxxxxx/
> Fixes: d591f6804e7e ("PCI: Wait for device readiness with Configuration RRS")
> Signed-off-by: Weili Qian <qianweili@xxxxxxxxxx>
> ---
> drivers/pci/quirks.c | 36 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 36 insertions(+)
>
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index d7f4ee634263..1df1756257d2 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -4205,6 +4205,36 @@ static int reset_hinic_vf_dev(struct pci_dev *pdev, bool probe)
> return 0;
> }
>
> +#define KUNPENG_OPERATION_WAIT_CNT 3000
> +#define KUNPENG_RESET_WAIT_TIME 20
> +
> +/* Device-specific reset method for Kunpeng accelerator virtual functions */
> +static int reset_kunpeng_acc_vf_dev(struct pci_dev *pdev, bool probe)
> +{
> + u32 wait_cnt = 0;
> + u32 cmd;
> +
> + if (probe)
> + return 0;
> +
> + pcie_flr(pdev);
> +
> + do {
> + pci_read_config_dword(pdev, PCI_COMMAND, &cmd);
> + if (!PCI_POSSIBLE_ERROR(cmd))
> + break;
> +
> + if (++wait_cnt > KUNPENG_OPERATION_WAIT_CNT) {
> + pci_warn(pdev, "wait for FLR ready timeout; giving up\n");
> + return -ENOTTY;
> + }
> +
> + msleep(KUNPENG_RESET_WAIT_TIME);
> + } while (true);
> +
> + return 0;
> +}
> +
> static const struct pci_dev_reset_methods pci_dev_reset_methods[] = {
> { PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82599_SFP_VF,
> reset_intel_82599_sfp_virtfn },
> @@ -4220,6 +4250,12 @@ static const struct pci_dev_reset_methods pci_dev_reset_methods[] = {
> reset_chelsio_generic_dev },
> { PCI_VENDOR_ID_HUAWEI, PCI_DEVICE_ID_HINIC_VF,
> reset_hinic_vf_dev },
> + { PCI_VENDOR_ID_HUAWEI, PCI_DEVICE_ID_HUAWEI_ZIP_VF,
> + reset_kunpeng_acc_vf_dev },
> + { PCI_VENDOR_ID_HUAWEI, PCI_DEVICE_ID_HUAWEI_SEC_VF,
> + reset_kunpeng_acc_vf_dev },
> + { PCI_VENDOR_ID_HUAWEI, PCI_DEVICE_ID_HUAWEI_HPRE_VF,
> + reset_kunpeng_acc_vf_dev },
> { 0 }
> };
>
> --
> 2.33.0
>
