Re: [PATCH 1/2] PCI: fix restoring resized BAR state on resume

From: Bjorn Helgaas
Date: Thu Jun 28 2018 - 14:28:01 EST


On Thu, Jun 14, 2018 at 02:21:45PM +0200, Christian König wrote:
> Resize BARs after resume to the expected size again.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=199959
> CC: stable@xxxxxxxxxxxxxxx # v4.15+

I added

Fixes: d6895ad39f3b ("drm/amdgpu: resize VRAM BAR for CPU access v6")
Fixes: 276b738deb5b ("PCI: Add resizable BAR infrastructure")

Per the bugzilla, the bug was bisected to d6895ad39f3b, which appeared
in v4.16. But 276b738deb5b appeared in v4.15, so I'm OK with the
v4.15+ stable tag.

> ---
> drivers/pci/pci.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index bd6f156dc3cf..d4685090378b 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1159,6 +1159,33 @@ static void pci_restore_config_space(struct pci_dev *pdev)
> }
> }
>
> +static void pci_restore_rebar_state(struct pci_dev *pdev)
> +{
> + unsigned int pos, nbars, i;
> + u32 ctrl;
> +
> + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_REBAR);
> + if (!pos)
> + return;
> +
> + pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
> + nbars = (ctrl & PCI_REBAR_CTRL_NBAR_MASK) >>
> + PCI_REBAR_CTRL_NBAR_SHIFT;
> +
> + for (i = 0; i < nbars; i++, pos += 8) {
> + struct resource *res;
> + int bar_idx, size;
> +
> + pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
> + bar_idx = ctrl & PCI_REBAR_CTRL_BAR_IDX;
> + res = pdev->resource + bar_idx;
> + size = order_base_2((resource_size(res) >> 20) | 1) - 1;
> + ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
> + ctrl |= size << 8;
> + pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
> + }
> +}
> +
> /**
> * pci_restore_state - Restore the saved state of a PCI device
> * @dev: - PCI device that we're dealing with
> @@ -1174,6 +1201,7 @@ void pci_restore_state(struct pci_dev *dev)
> pci_restore_pri_state(dev);
> pci_restore_ats_state(dev);
> pci_restore_vc_state(dev);
> + pci_restore_rebar_state(dev);
>
> pci_cleanup_aer_error_status_regs(dev);
>
> --
> 2.14.1
>