linux-kernel - Re: [PATCH for-next v6 6/7] RDMA/rxe: Add support for Send/Recv/Write/Read with ODP

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Message-ID: <ZPsv98Mr6ogzchCL@ziepe.ca>
Date:   Fri, 8 Sep 2023 11:30:15 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Daisuke Matsuda <matsuda-daisuke@...itsu.com>
Cc:     linux-rdma@...r.kernel.org, leon@...nel.org, zyjzyj2000@...il.com,
        linux-kernel@...r.kernel.org, rpearsonhpe@...il.com,
        yangx.jy@...itsu.com, lizhijian@...itsu.com, y-goto@...itsu.com
Subject: Re: [PATCH for-next v6 6/7] RDMA/rxe: Add support for
 Send/Recv/Write/Read with ODP

On Fri, Sep 08, 2023 at 03:26:47PM +0900, Daisuke Matsuda wrote:
> +static inline bool rxe_odp_check_pages(struct rxe_mr *mr, u64 iova,
> +				       int length, u32 flags)
> +{
> +	unsigned long lower, upper, idx;
> +	unsigned long hmm_flags = HMM_PFN_VALID;
> +	struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem);
> +	struct page *page;
> +	bool need_fault = false;
> +
> +	lower = rxe_mr_iova_to_index(mr, iova);
> +	upper = rxe_mr_iova_to_index(mr, iova + length - 1);
> +
> +	if (!(flags & RXE_PAGEFAULT_RDONLY))
> +		hmm_flags |= HMM_PFN_WRITE;
> +
> +	/* xarray is protected by umem_mutex */
> +	for (idx = lower; idx <= upper; idx++) {
> +		page = xa_load(&mr->page_list, idx);
> +
> +		if (!page || !(umem_odp->pfn_list[idx] & hmm_flags)) {
> +			need_fault = true;

Again you don't need the pfn_list and rxe should perhaps ideally find
some way to disable it since we store struct pages in the xarray.

This could also be a xas loop

Jason