[PATCH 1/2] ntb_transport: Fix bug with max_mw_size parameter

[Logan Gunthorpe]

When using the max_mw_size parameter of ntb_transport to limit the size of
the Memory windows, communication cannot be established and the queues
freeze.

This is because the mw_size that's reported to the peer is correctly
limited but the size used locally is not. So the MW is initialized
with a buffer smaller than the window but the TX side is using the
full window. This means the TX side will be writing to a region of the
window that points nowhere.

This is easily fixed by applying the same limit to tx_size in
ntb_transport_init_queue().

Fixes: e26a5843f7f5 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
Signed-off-by: Logan Gunthorpe <log...@deltatee.com>
Cc: Jon Mason <jdm...@kudzu.us>
Cc: Dave Jiang <dave....@intel.com>
Cc: Allen Hubbe <Allen...@emc.com>
---
drivers/ntb/ntb_transport.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index 045e3dd4750e..9878c48826e3 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -1003,6 +1003,9 @@ static int ntb_transport_init_queue(struct ntb_transport_ctx *nt,
mw_base = nt->mw_vec[mw_num].phys_addr;
mw_size = nt->mw_vec[mw_num].phys_size;

+ if (max_mw_size && mw_size > max_mw_size)
+ mw_size = max_mw_size;
+
tx_size = (unsigned int)mw_size / num_qps_mw;
qp_offset = tx_size * (qp_num / mw_count);

--
2.11.0

[Allen Hubbe]

From: Logan Gunthorpe

> When using the max_mw_size parameter of ntb_transport to limit the size of
> the Memory windows, communication cannot be established and the queues
> freeze.
>
> This is because the mw_size that's reported to the peer is correctly
> limited but the size used locally is not. So the MW is initialized
> with a buffer smaller than the window but the TX side is using the
> full window. This means the TX side will be writing to a region of the
> window that points nowhere.
>
> This is easily fixed by applying the same limit to tx_size in
> ntb_transport_init_queue().
>
> Fixes: e26a5843f7f5 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
> Signed-off-by: Logan Gunthorpe <log...@deltatee.com>
> Cc: Jon Mason <jdm...@kudzu.us>
> Cc: Dave Jiang <dave....@intel.com>
> Cc: Allen Hubbe <Allen...@emc.com>

Acked-by: Allen Hubbe <Allen...@dell.com>

[Logan Gunthorpe]

When using the max_mw_size parameter of ntb_transport to limit the size of
the Memory windows, communication cannot be established and the queues
freeze.

This is because the mw_size that's reported to the peer is correctly
limited but the size used locally is not. So the MW is initialized
with a buffer smaller than the window but the TX side is using the
full window. This means the TX side will be writing to a region of the
window that points nowhere.

This is easily fixed by applying the same limit to tx_size in
ntb_transport_init_queue().

Fixes: e26a5843f7f5 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
Signed-off-by: Logan Gunthorpe <log...@deltatee.com>

Acked-by: Allen Hubbe <Allen...@dell.com>

Cc: Jon Mason <jdm...@kudzu.us>
Cc: Dave Jiang <dave....@intel.com>

[Jon Mason]

On Mon, Dec 18, 2017 at 11:25:05AM -0700, Logan Gunthorpe wrote:
> When using the max_mw_size parameter of ntb_transport to limit the size of
> the Memory windows, communication cannot be established and the queues
> freeze.
>
> This is because the mw_size that's reported to the peer is correctly
> limited but the size used locally is not. So the MW is initialized
> with a buffer smaller than the window but the TX side is using the
> full window. This means the TX side will be writing to a region of the
> window that points nowhere.
>
> This is easily fixed by applying the same limit to tx_size in
> ntb_transport_init_queue().

Applied to ntb-next.

Thanks,
Jon

>
> Fixes: e26a5843f7f5 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
> Signed-off-by: Logan Gunthorpe <log...@deltatee.com>
> Acked-by: Allen Hubbe <Allen...@dell.com>
> Cc: Jon Mason <jdm...@kudzu.us>
> Cc: Dave Jiang <dave....@intel.com>
> ---
> drivers/ntb/ntb_transport.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
> index 045e3dd4750e..9878c48826e3 100644
> --- a/drivers/ntb/ntb_transport.c
> +++ b/drivers/ntb/ntb_transport.c
> @@ -1003,6 +1003,9 @@ static int ntb_transport_init_queue(struct ntb_transport_ctx *nt,
> mw_base = nt->mw_vec[mw_num].phys_addr;
> mw_size = nt->mw_vec[mw_num].phys_size;
>
> + if (max_mw_size && mw_size > max_mw_size)
> + mw_size = max_mw_size;
> +
> tx_size = (unsigned int)mw_size / num_qps_mw;
> qp_offset = tx_size * (qp_num / mw_count);
>
> --
> 2.11.0
>

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