Re: [PATCH v6 4/6] vfio/nvgrace-gpu: split the code to wait for GPU ready

Alex Williamson
2025-11-25T20:53:05Z

On Tue, 25 Nov 2025 17:30:11 +0000
<ankita@nvidia.com> wrote:

> From: Ankit Agrawal <ankita@nvidia.com>
>
> Split the function that check for the GPU device being ready on
> the probe.
>
> Move the code to wait for the GPU to be ready through BAR0 register
> reads to a separate function. This would help reuse the code.
>
> Reviewed-by: Shameer Kolothum <skolothumtho@nvidia.com>
> Signed-off-by: Ankit Agrawal <ankita@nvidia.com>

As noted last round:

Fixes: ...

And note the fix in the commit log.

> ---
> drivers/vfio/pci/nvgrace-gpu/main.c | 29 +++++++++++++++++------------
> 1 file changed, 17 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/vfio/pci/nvgrace-gpu/main.c b/drivers/vfio/pci/nvgrace-gpu/main.c
> index 8a982310b188..2b736cb82f38 100644
> --- a/drivers/vfio/pci/nvgrace-gpu/main.c
> +++ b/drivers/vfio/pci/nvgrace-gpu/main.c
> @@ -130,6 +130,20 @@ static void nvgrace_gpu_close_device(struct vfio_device *core_vdev)
> vfio_pci_core_close_device(core_vdev);
> }
>
> +static int nvgrace_gpu_wait_device_ready(void __iomem *io)
> +{
> + unsigned long timeout = jiffies + msecs_to_jiffies(POLL_TIMEOUT_MS);
> +
> + do {
> + if ((ioread32(io + C2C_LINK_BAR0_OFFSET) == STATUS_READY) &&
> + (ioread32(io + HBM_TRAINING_BAR0_OFFSET) == STATUS_READY))
> + return 0;
> + msleep(POLL_QUANTUM_MS);
> + } while (!time_after(jiffies, timeout));
> +
> + return -ETIME;
> +}
> +
> static unsigned long addr_to_pgoff(struct vm_area_struct *vma,
> unsigned long addr)
> {
> @@ -933,9 +947,8 @@ static bool nvgrace_gpu_has_mig_hw_bug(struct pci_dev *pdev)
> * Ensure that the BAR0 region is enabled before accessing the
> * registers.
> */
> -static int nvgrace_gpu_wait_device_ready(struct pci_dev *pdev)
> +static int nvgrace_gpu_probe_check_device_ready(struct pci_dev *pdev)
> {
> - unsigned long timeout = jiffies + msecs_to_jiffies(POLL_TIMEOUT_MS);
> void __iomem *io;
> int ret = -ETIME;

And this initialization is unnecessary. Thanks,

Alex

>
> @@ -953,16 +966,8 @@ static int nvgrace_gpu_wait_device_ready(struct pci_dev *pdev)
> goto iomap_exit;
> }
>
> - do {
> - if ((ioread32(io + C2C_LINK_BAR0_OFFSET) == STATUS_READY) &&
> - (ioread32(io + HBM_TRAINING_BAR0_OFFSET) == STATUS_READY)) {
> - ret = 0;
> - goto reg_check_exit;
> - }
> - msleep(POLL_QUANTUM_MS);
> - } while (!time_after(jiffies, timeout));
> + ret = nvgrace_gpu_wait_device_ready(io);
>
> -reg_check_exit:
> pci_iounmap(pdev, io);
> iomap_exit:
> pci_release_selected_regions(pdev, 1 << 0);
> @@ -979,7 +984,7 @@ static int nvgrace_gpu_probe(struct pci_dev *pdev,
> u64 memphys, memlength;
> int ret;
>
> - ret = nvgrace_gpu_wait_device_ready(pdev);
> + ret = nvgrace_gpu_probe_check_device_ready(pdev);
> if (ret)
> return ret;
>