Re: [RFC PATCH v4 13/38] PCI: endpoint: pci-epf-vntb: Support BAR subrange mappings for MWs

Frank Li
2026-01-19T20:26:50Z

On Sun, Jan 18, 2026 at 10:54:15PM +0900, Koichiro Den wrote:
> pci-epf-vntb can pack multiple memory windows into a single BAR using
> mwN_offset. With the NTB core gaining support for programming multiple
> translation ranges for a window, the EPF needs to provide the per-BAR
> subrange layout to the endpoint controller (EPC).
>
> Implement .mw_set_trans_ranges() for pci-epf-vntb. Track subranges for
> each BAR and pass them to pci_epc_set_bar() so EPC drivers can select an
> appropriate inbound mapping mode (e.g. Address Match mode on DesignWare
> controllers) when subrange mappings are required.
>
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---
> drivers/pci/endpoint/functions/pci-epf-vntb.c | 183 +++++++++++++++++-
> 1 file changed, 175 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index 39e784e21236..98128c2c5079 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> @@ -42,6 +42,7 @@
> #include <linux/log2.h>
> #include <linux/module.h>
> #include <linux/slab.h>
> +#include <linux/sort.h>
>
> #include <linux/pci-ep-msi.h>
> #include <linux/pci-epc.h>
> @@ -144,6 +145,10 @@ struct epf_ntb {
>
> enum pci_barno epf_ntb_bar[VNTB_BAR_NUM];
>
> + /* Cache for subrange mapping */
> + struct ntb_mw_subrange *mw_subrange[MAX_MW];
> + unsigned int num_subrange[MAX_MW];
> +
> struct epf_ntb_ctrl *reg;
>
> u32 *epf_db;
> @@ -736,6 +741,7 @@ static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
> ntb->epf->bar[barno].flags |= upper_32_bits(size) ?
> PCI_BASE_ADDRESS_MEM_TYPE_64 :
> PCI_BASE_ADDRESS_MEM_TYPE_32;
> + ntb->epf->bar[barno].num_submap = 0;
>
> ret = pci_epc_set_bar(ntb->epf->epc,
> ntb->epf->func_no,
> @@ -1405,28 +1411,188 @@ static int vntb_epf_db_set_mask(struct ntb_dev *ntb, u64 db_bits)
> return 0;
> }
>
> -static int vntb_epf_mw_set_trans(struct ntb_dev *ndev, int pidx, int idx,
> - dma_addr_t addr, resource_size_t size)
> +struct vntb_mw_order {
> + u64 off;
> + unsigned int mw;
> +};
> +
> +static int vntb_cmp_mw_order(const void *a, const void *b)
> +{
> + const struct vntb_mw_order *ma = a;
> + const struct vntb_mw_order *mb = b;
> +
> + if (ma->off < mb->off)
> + return -1;
> + if (ma->off > mb->off)
> + return 1;
> + return 0;
> +}
> +
> +static int vntb_epf_mw_set_trans_ranges(struct ntb_dev *ndev, int pidx, int idx,
> + unsigned int num_ranges,
> + const struct ntb_mw_subrange *ranges)
> {
> struct epf_ntb *ntb = ntb_ndev(ndev);
> + struct pci_epf_bar_submap *submap;
> + struct vntb_mw_order mws[MAX_MW];
> struct pci_epf_bar *epf_bar;
> + struct ntb_mw_subrange *r;
> enum pci_barno barno;
> + struct device *dev, *epf_dev;
> + unsigned int total_ranges = 0;
> + unsigned int mw_cnt = 0;
> + unsigned int cur = 0;
> + u64 expected_off = 0;
> + unsigned int i, j;
> int ret;
> +
> + dev = &ntb->ntb->dev;
> + epf_dev = &ntb->epf->dev;
> + barno = ntb->epf_ntb_bar[BAR_MW1 + idx];
> + epf_bar = &ntb->epf->bar[barno];
> + epf_bar->barno = barno;
> +
> + r = devm_kmemdup(epf_dev, ranges, num_ranges * sizeof(*ranges), GFP_KERNEL);

size_mul(sizeof(*ranges), num_ranges)

> + if (!r)
> + return -ENOMEM;
> +
> + if (ntb->mw_subrange[idx])
> + devm_kfree(epf_dev, ntb->mw_subrange[idx]);
> +
> + ntb->mw_subrange[idx] = r;
> + ntb->num_subrange[idx] = num_ranges;
> +
> + /* Defer pci_epc_set_bar() until all MWs in this BAR have range info. */
> + for (i = 0; i < MAX_MW; i++) {
> + enum pci_barno bar = ntb->epf_ntb_bar[BAR_MW1 + i];
> +
> + if (bar != barno)
> + continue;
> + if (!ntb->num_subrange[i])
> + return 0;
> +
> + mws[mw_cnt].mw = i;
> + mws[mw_cnt].off = ntb->mws_offset[i];
> + mw_cnt++;
> + }
> +
> + sort(mws, mw_cnt, sizeof(mws[0]), vntb_cmp_mw_order, NULL);

Can we require mws_offset is ordered? So needn't sort here.

> +
> + /* BAR submap must cover the whole BAR with no holes. */
> + for (i = 0; i < mw_cnt; i++) {
> + unsigned int mw = mws[i].mw;
> + u64 sum = 0;
> +
> + if (mws[i].off != expected_off) {

can we all use size instead 'off' to keep align with submap?

Frank
> + dev_err(dev,
> + "BAR%d: hole/overlap at %#llx (MW%d@%#llx)\n",
> + barno, expected_off, mw + 1, mws[i].off);
> + return -EINVAL;
> + }
> +
> + total_ranges += ntb->num_subrange[mw];
> + for (j = 0; j < ntb->num_subrange[mw]; j++)
> + sum += ntb->mw_subrange[mw][j].size;
> +
> + if (sum != ntb->mws_size[mw]) {
> + dev_err(dev,
> + "MW%d: ranges size %#llx != window size %#llx\n",
> + mw + 1, sum, ntb->mws_size[mw]);
> + return -EINVAL;
> + }
> + expected_off += ntb->mws_size[mw];
> + }
> +
> + submap = devm_krealloc_array(epf_dev, epf_bar->submap, total_ranges,
> + sizeof(*submap), GFP_KERNEL);
> + if (!submap)
> + return -ENOMEM;
> +
> + epf_bar->submap = submap;
> + epf_bar->num_submap = total_ranges;
> + dev_dbg(dev, "Requesting BAR%d layout (#. of subranges is %u):\n",
> + barno, total_ranges);
> +
> + for (i = 0; i < mw_cnt; i++) {
> + unsigned int mw = mws[i].mw;
> +
> + dev_dbg(dev, "- MW%d\n", 1 + mw);
> + for (j = 0; j < ntb->num_subrange[mw]; j++) {
> + dev_dbg(dev, " - addr/size = %#llx/%#llx\n",
> + ntb->mw_subrange[mw][j].addr,
> + ntb->mw_subrange[mw][j].size);
> + submap[cur].phys_addr = ntb->mw_subrange[mw][j].addr;
> + submap[cur].size = ntb->mw_subrange[mw][j].size;
> + cur++;
> + }
> + }
> +
> + ret = pci_epc_set_bar(ntb->epf->epc, ntb->epf->func_no,
> + ntb->epf->vfunc_no, epf_bar);
> + if (ret)
> + dev_err(dev, "BAR%d: failed to program mappings for MW%d: %d\n",
> + barno, idx + 1, ret);
> +
> + return ret;
> +}
> +
> +static int vntb_epf_mw_set_trans(struct ntb_dev *ndev, int pidx, int idx,
> + dma_addr_t addr, resource_size_t size)
> +{
> + struct epf_ntb *ntb = ntb_ndev(ndev);
> + struct pci_epf_bar *epf_bar;
> + resource_size_t bar_size;
> + enum pci_barno barno;
> struct device *dev;
> + unsigned int i;
> + int ret;
>
> dev = &ntb->ntb->dev;
> barno = ntb->epf_ntb_bar[BAR_MW1 + idx];
> epf_bar = &ntb->epf->bar[barno];
> epf_bar->phys_addr = addr;
> epf_bar->barno = barno;
> - epf_bar->size = size;
>
> - ret = pci_epc_set_bar(ntb->epf->epc, 0, 0, epf_bar);
> - if (ret) {
> - dev_err(dev, "failure set mw trans\n");
> - return ret;
> + bar_size = epf_bar->size;
> + if (!bar_size || !size)
> + return -EINVAL;
> +
> + if (size != ntb->mws_size[idx])
> + return -EINVAL;
> +
> + /*
> + * Even if the caller intends to map the entire MW, the MW might
> + * actually be just a part of the BAR. In that case, redirect the
> + * handling to vntb_epf_mw_set_trans_ranges().
> + */
> + if (size < bar_size) {
> + struct ntb_mw_subrange r = {
> + .addr = addr,
> + .size = size,
> + };
> + return vntb_epf_mw_set_trans_ranges(ndev, pidx, idx, 1, &r);
> }
> - return 0;
> +
> + /* Drop any stale cache for the BAR. */
> + for (i = 0; i < MAX_MW; i++) {
> + if (ntb->epf_ntb_bar[BAR_MW1 + i] != barno)
> + continue;
> + devm_kfree(&ntb->epf->dev, ntb->mw_subrange[i]);
> + ntb->mw_subrange[i] = NULL;
> + ntb->num_subrange[i] = 0;
> + }
> +
> + /* Not use subrange mapping. If it's used in the past, clear it off. */
> + devm_kfree(&ntb->epf->dev, epf_bar->submap);
> + epf_bar->submap = NULL;
> + epf_bar->num_submap = 0;
> +
> + ret = pci_epc_set_bar(ntb->epf->epc, ntb->epf->func_no,
> + ntb->epf->vfunc_no, epf_bar);
> + if (ret)
> + dev_err(dev, "failure set mw trans\n");
> +
> + return ret;
> }
>
> static int vntb_epf_mw_clear_trans(struct ntb_dev *ntb, int pidx, int idx)
> @@ -1590,6 +1756,7 @@ static const struct ntb_dev_ops vntb_epf_ops = {
> .db_vector_mask = vntb_epf_db_vector_mask,
> .db_set_mask = vntb_epf_db_set_mask,
> .mw_set_trans = vntb_epf_mw_set_trans,
> + .mw_set_trans_ranges = vntb_epf_mw_set_trans_ranges,
> .mw_clear_trans = vntb_epf_mw_clear_trans,
> .peer_mw_get_addr = vntb_epf_peer_mw_get_addr,
> .link_enable = vntb_epf_link_enable,
> --
> 2.51.0
>