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Message-ID: <o47cam4tmc6274mw6oucwks3cycdjcfycwb2r6pgkndhlk3wmm@oau6km62lugo>
Date: Tue, 2 Dec 2025 15:23:15 +0900
From: Koichiro Den <den@...inux.co.jp>
To: Frank Li <Frank.li@....com>
Cc: ntb@...ts.linux.dev, linux-pci@...r.kernel.org,
dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org, mani@...nel.org,
kwilczynski@...nel.org, kishon@...nel.org, bhelgaas@...gle.com, corbet@....net,
vkoul@...nel.org, jdmason@...zu.us, dave.jiang@...el.com, allenbh@...il.com,
Basavaraj.Natikar@....com, Shyam-sundar.S-k@....com, kurt.schwemmer@...rosemi.com,
logang@...tatee.com, jingoohan1@...il.com, lpieralisi@...nel.org, robh@...nel.org,
jbrunet@...libre.com, fancer.lancer@...il.com, arnd@...db.de, pstanner@...hat.com,
elfring@...rs.sourceforge.net
Subject: Re: [RFC PATCH v2 02/27] PCI: endpoint: pci-epf-vntb: Add mwN_offset
configfs attributes
On Mon, Dec 01, 2025 at 02:11:07PM -0500, Frank Li wrote:
> On Sun, Nov 30, 2025 at 01:03:40AM +0900, Koichiro Den wrote:
> > Introduce new mwN_offset configfs attributes to specify memory window
> > offsets. This enables mapping multiple windows into a single BAR at
>
> This need update documents. But I am not clear how multiple windows map
> into a single BAR, could you please give me an example, how to config
> more than 2 memory space to one bar by echo to sys file commands.
For some reason, I mistakenly dropped the doc update that I had added in RFC v1:
https://lore.kernel.org/all/20251023071916.901355-26-den@valinux.co.jp/
I'll restore it in the next iteration.
Thanks for the review.
-Koichiro
>
> Frank
>
> > arbitrary offsets, improving layout flexibility.
> >
> > Signed-off-by: Koichiro Den <den@...inux.co.jp>
> > ---
> > drivers/pci/endpoint/functions/pci-epf-vntb.c | 133 ++++++++++++++++--
> > 1 file changed, 120 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> > index 6c4c78915970..1ff414703566 100644
> > --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> > +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> > @@ -39,6 +39,7 @@
> > #include <linux/atomic.h>
> > #include <linux/delay.h>
> > #include <linux/io.h>
> > +#include <linux/log2.h>
> > #include <linux/module.h>
> > #include <linux/slab.h>
> >
> > @@ -111,7 +112,8 @@ struct epf_ntb_ctrl {
> > u64 addr;
> > u64 size;
> > u32 num_mws;
> > - u32 reserved;
> > + u32 mw_offset[MAX_MW];
> > + u32 mw_size[MAX_MW];
> > u32 spad_offset;
> > u32 spad_count;
> > u32 db_entry_size;
> > @@ -128,6 +130,7 @@ struct epf_ntb {
> > u32 db_count;
> > u32 spad_count;
> > u64 mws_size[MAX_MW];
> > + u64 mws_offset[MAX_MW];
> > atomic64_t db;
> > u32 vbus_number;
> > u16 vntb_pid;
> > @@ -458,6 +461,8 @@ static int epf_ntb_config_spad_bar_alloc(struct epf_ntb *ntb)
> >
> > ctrl->spad_count = spad_count;
> > ctrl->num_mws = ntb->num_mws;
> > + memset(ctrl->mw_offset, 0, sizeof(ctrl->mw_offset));
> > + memset(ctrl->mw_size, 0, sizeof(ctrl->mw_size));
> > ntb->spad_size = spad_size;
> >
> > ctrl->db_entry_size = sizeof(u32);
> > @@ -689,15 +694,31 @@ static void epf_ntb_db_bar_clear(struct epf_ntb *ntb)
> > */
> > static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
> > {
> > + struct device *dev = &ntb->epf->dev;
> > + u64 bar_ends[BAR_5 + 1] = { 0 };
> > + unsigned long bars_used = 0;
> > + enum pci_barno barno;
> > + u64 off, size, end;
> > int ret = 0;
> > int i;
> > - u64 size;
> > - enum pci_barno barno;
> > - struct device *dev = &ntb->epf->dev;
> >
> > for (i = 0; i < ntb->num_mws; i++) {
> > - size = ntb->mws_size[i];
> > barno = ntb->epf_ntb_bar[BAR_MW1 + i];
> > + off = ntb->mws_offset[i];
> > + size = ntb->mws_size[i];
> > + end = off + size;
> > + if (end > bar_ends[barno])
> > + bar_ends[barno] = end;
> > + bars_used |= BIT(barno);
> > + }
> > +
> > + for (barno = BAR_0; barno <= BAR_5; barno++) {
> > + if (!(bars_used & BIT(barno)))
> > + continue;
> > + if (bar_ends[barno] < SZ_4K)
> > + size = SZ_4K;
> > + else
> > + size = roundup_pow_of_two(bar_ends[barno]);
> >
> > ntb->epf->bar[barno].barno = barno;
> > ntb->epf->bar[barno].size = size;
> > @@ -713,8 +734,12 @@ static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
> > &ntb->epf->bar[barno]);
> > if (ret) {
> > dev_err(dev, "MW set failed\n");
> > - goto err_alloc_mem;
> > + goto err_set_bar;
> > }
> > + }
> > +
> > + for (i = 0; i < ntb->num_mws; i++) {
> > + size = ntb->mws_size[i];
> >
> > /* Allocate EPC outbound memory windows to vpci vntb device */
> > ntb->vpci_mw_addr[i] = pci_epc_mem_alloc_addr(ntb->epf->epc,
> > @@ -723,19 +748,31 @@ static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
> > if (!ntb->vpci_mw_addr[i]) {
> > ret = -ENOMEM;
> > dev_err(dev, "Failed to allocate source address\n");
> > - goto err_set_bar;
> > + goto err_alloc_mem;
> > }
> > }
> >
> > + for (i = 0; i < ntb->num_mws; i++) {
> > + ntb->reg->mw_offset[i] = (u32)ntb->mws_offset[i];
> > + ntb->reg->mw_size[i] = (u32)ntb->mws_size[i];
> > + }
> > +
> > return ret;
> >
> > -err_set_bar:
> > - pci_epc_clear_bar(ntb->epf->epc,
> > - ntb->epf->func_no,
> > - ntb->epf->vfunc_no,
> > - &ntb->epf->bar[barno]);
> > err_alloc_mem:
> > - epf_ntb_mw_bar_clear(ntb, i);
> > + while (--i >= 0)
> > + pci_epc_mem_free_addr(ntb->epf->epc,
> > + ntb->vpci_mw_phy[i],
> > + ntb->vpci_mw_addr[i],
> > + ntb->mws_size[i]);
> > +err_set_bar:
> > + while (--barno >= BAR_0)
> > + if (bars_used & BIT(barno))
> > + pci_epc_clear_bar(ntb->epf->epc,
> > + ntb->epf->func_no,
> > + ntb->epf->vfunc_no,
> > + &ntb->epf->bar[barno]);
> > +
> > return ret;
> > }
> >
> > @@ -1039,6 +1076,60 @@ static ssize_t epf_ntb_##_name##_store(struct config_item *item, \
> > return len; \
> > }
> >
> > +#define EPF_NTB_MW_OFF_R(_name) \
> > +static ssize_t epf_ntb_##_name##_show(struct config_item *item, \
> > + char *page) \
> > +{ \
> > + struct config_group *group = to_config_group(item); \
> > + struct epf_ntb *ntb = to_epf_ntb(group); \
> > + struct device *dev = &ntb->epf->dev; \
> > + int win_no, idx; \
> > + \
> > + if (sscanf(#_name, "mw%d_offset", &win_no) != 1) \
> > + return -EINVAL; \
> > + \
> > + idx = win_no - 1; \
> > + if (idx < 0 || idx >= ntb->num_mws) { \
> > + dev_err(dev, "MW%d out of range (num_mws=%d)\n", \
> > + win_no, ntb->num_mws); \
> > + return -EINVAL; \
> > + } \
> > + \
> > + idx = array_index_nospec(idx, ntb->num_mws); \
> > + return sprintf(page, "%lld\n", ntb->mws_offset[idx]); \
> > +}
> > +
> > +#define EPF_NTB_MW_OFF_W(_name) \
> > +static ssize_t epf_ntb_##_name##_store(struct config_item *item, \
> > + const char *page, size_t len) \
> > +{ \
> > + struct config_group *group = to_config_group(item); \
> > + struct epf_ntb *ntb = to_epf_ntb(group); \
> > + struct device *dev = &ntb->epf->dev; \
> > + int win_no, idx; \
> > + u64 val; \
> > + int ret; \
> > + \
> > + ret = kstrtou64(page, 0, &val); \
> > + if (ret) \
> > + return ret; \
> > + \
> > + if (sscanf(#_name, "mw%d_offset", &win_no) != 1) \
> > + return -EINVAL; \
> > + \
> > + idx = win_no - 1; \
> > + if (idx < 0 || idx >= ntb->num_mws) { \
> > + dev_err(dev, "MW%d out of range (num_mws=%d)\n", \
> > + win_no, ntb->num_mws); \
> > + return -EINVAL; \
> > + } \
> > + \
> > + idx = array_index_nospec(idx, ntb->num_mws); \
> > + ntb->mws_offset[idx] = val; \
> > + \
> > + return len; \
> > +}
> > +
> > #define EPF_NTB_BAR_R(_name, _id) \
> > static ssize_t epf_ntb_##_name##_show(struct config_item *item, \
> > char *page) \
> > @@ -1109,6 +1200,14 @@ EPF_NTB_MW_R(mw3)
> > EPF_NTB_MW_W(mw3)
> > EPF_NTB_MW_R(mw4)
> > EPF_NTB_MW_W(mw4)
> > +EPF_NTB_MW_OFF_R(mw1_offset)
> > +EPF_NTB_MW_OFF_W(mw1_offset)
> > +EPF_NTB_MW_OFF_R(mw2_offset)
> > +EPF_NTB_MW_OFF_W(mw2_offset)
> > +EPF_NTB_MW_OFF_R(mw3_offset)
> > +EPF_NTB_MW_OFF_W(mw3_offset)
> > +EPF_NTB_MW_OFF_R(mw4_offset)
> > +EPF_NTB_MW_OFF_W(mw4_offset)
> > EPF_NTB_BAR_R(ctrl_bar, BAR_CONFIG)
> > EPF_NTB_BAR_W(ctrl_bar, BAR_CONFIG)
> > EPF_NTB_BAR_R(db_bar, BAR_DB)
> > @@ -1129,6 +1228,10 @@ CONFIGFS_ATTR(epf_ntb_, mw1);
> > CONFIGFS_ATTR(epf_ntb_, mw2);
> > CONFIGFS_ATTR(epf_ntb_, mw3);
> > CONFIGFS_ATTR(epf_ntb_, mw4);
> > +CONFIGFS_ATTR(epf_ntb_, mw1_offset);
> > +CONFIGFS_ATTR(epf_ntb_, mw2_offset);
> > +CONFIGFS_ATTR(epf_ntb_, mw3_offset);
> > +CONFIGFS_ATTR(epf_ntb_, mw4_offset);
> > CONFIGFS_ATTR(epf_ntb_, vbus_number);
> > CONFIGFS_ATTR(epf_ntb_, vntb_pid);
> > CONFIGFS_ATTR(epf_ntb_, vntb_vid);
> > @@ -1147,6 +1250,10 @@ static struct configfs_attribute *epf_ntb_attrs[] = {
> > &epf_ntb_attr_mw2,
> > &epf_ntb_attr_mw3,
> > &epf_ntb_attr_mw4,
> > + &epf_ntb_attr_mw1_offset,
> > + &epf_ntb_attr_mw2_offset,
> > + &epf_ntb_attr_mw3_offset,
> > + &epf_ntb_attr_mw4_offset,
> > &epf_ntb_attr_vbus_number,
> > &epf_ntb_attr_vntb_pid,
> > &epf_ntb_attr_vntb_vid,
> > --
> > 2.48.1
> >
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