Re: [PATCH] RDMA/cxgb3: fail get_dma_mr if the memory footprint can exceed 32b

[Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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On 07/22/2015 03:14 PM, Steve Wise wrote:
> T3 HW only supports MRs of length < 4GB.  If the system can have more
> than that we need to fail dma mr allocation so we con't create a MR that
> cannot span the entire possible memory space.
> 
> Signed-off-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
> ---
> 
>  drivers/infiniband/hw/cxgb3/iwch_provider.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/cxgb3/iwch_provider.c b/drivers/infiniband/hw/cxgb3/iwch_provider.c
> index b1b7323..bbbe018 100644
> --- a/drivers/infiniband/hw/cxgb3/iwch_provider.c
> +++ b/drivers/infiniband/hw/cxgb3/iwch_provider.c
> @@ -736,6 +736,10 @@ static struct ib_mr *iwch_get_dma_mr(struct ib_pd *pd, int acc)
>  	/*
>  	 * T3 only supports 32 bits of size.
>  	 */
> +	if (sizeof(phys_addr_t) > 4) {
> +		pr_warn_once(MOD "Cannot support dma_mrs on this platform.\n");
> +		return ERR_PTR(-ENOTSUPP);
> +	}
>  	bl.size = 0xffffffff;
>  	bl.addr = 0;
>  	kva = 0;

Should this be a static check of the pointer size versus installed
memory?  Would it be possible to have this work for machines with less
than 4GB of physical memory even if they have 64bit pointers, or are you
concerned that hotplug memory could take us over the limit after
registration and cause problems?


-- 
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
              GPG KeyID: 0E572FDD



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