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SubjectRe: [PATCH] NTB: ntb_hw_switchtec: Fix peer BAR bug in switchtec_ntb_init_shared_mw
On Tue, Oct 17, 2017 at 4:22 PM,  <dmeyer@gigaio.com> wrote:
> From: Doug Meyer <dmeyer@gigaio.com>
>
> This resolves a bug which may incorrectly configure the peer host's
> LUT for shared memory window access. The code was using the local
> host's first BAR number, rather than the peer hosts's first BAR
> number, to determine what peer NT control register to program.
>
> The bug will cause the Switchtec NTB link to work only if both peers
> have the same first NTB BAR configured. In all other configurations,
> the link will not come up, failing silently.
>
> When both hosts have the same first BAR, the configuration works only
> because the first BAR numbers happent to be the same. When the hosts
> do not have the same first BAR, then the LUT translation will not be
> configured in the correct peer LUT and will not give the peer the
> shared memory window access required for the link to operate.
>
> Signed-off-by: Doug Meyer <dmeyer@gigaio.com>

Looks good to me. I'd prefer to have a "Fixes: " here, but I can add
it if there are no other objections to this patch.

Thanks,
Jon

> ---
> drivers/ntb/hw/mscc/ntb_hw_switchtec.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/ntb/hw/mscc/ntb_hw_switchtec.c b/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
> index afe8ed6..ca0334a 100644
> --- a/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
> +++ b/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
> @@ -964,7 +964,8 @@ static void switchtec_ntb_init_shared(struct switchtec_ntb *sndev)
> static int switchtec_ntb_init_shared_mw(struct switchtec_ntb *sndev)
> {
> struct ntb_ctrl_regs __iomem *ctl = sndev->mmio_peer_ctrl;
> - int bar = sndev->direct_mw_to_bar[0];
> + int self_bar = sndev->direct_mw_to_bar[0];
> + int peer_bar = sndev->peer_direct_mw_to_bar[0];
> u32 ctl_val;
> int rc;
>
> @@ -985,12 +986,12 @@ static int switchtec_ntb_init_shared_mw(struct switchtec_ntb *sndev)
> if (rc)
> goto unalloc_and_exit;
>
> - ctl_val = ioread32(&ctl->bar_entry[bar].ctl);
> + ctl_val = ioread32(&ctl->bar_entry[peer_bar].ctl);
> ctl_val &= 0xFF;
> ctl_val |= NTB_CTRL_BAR_LUT_WIN_EN;
> ctl_val |= ilog2(LUT_SIZE) << 8;
> ctl_val |= (sndev->nr_lut_mw - 1) << 14;
> - iowrite32(ctl_val, &ctl->bar_entry[bar].ctl);
> + iowrite32(ctl_val, &ctl->bar_entry[peer_bar].ctl);
>
> iowrite64((NTB_CTRL_LUT_EN | (sndev->self_partition << 1) |
> sndev->self_shared_dma),
> @@ -1009,7 +1010,7 @@ static int switchtec_ntb_init_shared_mw(struct switchtec_ntb *sndev)
> goto unalloc_and_exit;
> }
>
> - sndev->peer_shared = pci_iomap(sndev->stdev->pdev, bar, LUT_SIZE);
> + sndev->peer_shared = pci_iomap(sndev->stdev->pdev, self_bar, LUT_SIZE);
> if (!sndev->peer_shared) {
> rc = -ENOMEM;
> goto unalloc_and_exit;
> --
> 1.8.3.1
>

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