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Message-ID: <aUTER+i1707eGdqN@lizhi-Precision-Tower-5810>
Date: Thu, 18 Dec 2025 22:19:35 -0500
From: Frank Li <Frank.li@....com>
To: Koichiro Den <den@...inux.co.jp>
Cc: dave.jiang@...el.com, ntb@...ts.linux.dev, linux-pci@...r.kernel.org,
dmaengine@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
mani@...nel.org, kwilczynski@...nel.org, kishon@...nel.org,
bhelgaas@...gle.com, corbet@....net, geert+renesas@...der.be,
magnus.damm@...il.com, robh@...nel.org, krzk+dt@...nel.org,
conor+dt@...nel.org, vkoul@...nel.org, joro@...tes.org,
will@...nel.org, robin.murphy@....com, jdmason@...zu.us,
allenbh@...il.com, andrew+netdev@...n.ch, davem@...emloft.net,
edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
Basavaraj.Natikar@....com, Shyam-sundar.S-k@....com,
kurt.schwemmer@...rosemi.com, logang@...tatee.com,
jingoohan1@...il.com, lpieralisi@...nel.org, utkarsh02t@...il.com,
jbrunet@...libre.com, dlemoal@...nel.org, arnd@...db.de,
elfring@...rs.sourceforge.net
Subject: Re: [RFC PATCH v3 02/35] NTB: epf: Add mwN_offset support and config
region versioning
On Thu, Dec 18, 2025 at 12:15:36AM +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
> arbitrary offsets, improving layout flexibility.
>
> Extend the control register region and add a 32-bit config version
> field. Reuse NTB_EPF_TOPOLOGY (0x0C), which is currently unused, as the
> version register. The endpoint function driver writes 1
> (NTB_EPF_CTRL_VERSION_V1), and ntb_hw_epf reads it at probe time and
> refuses to bind to unknown versions.
>
> Endpoint running with an older kernel that do not program
Is it zero if EP have not program it?
> NTB_EPF_CTRL_VERSION will be rejected early by host with newer kernel,
> instead of misbehaving at runtime.
If old one is 0, try best to compatible with old version.
Frank
>
> Signed-off-by: Koichiro Den <den@...inux.co.jp>
> ---
> drivers/ntb/hw/epf/ntb_hw_epf.c | 44 +++++-
> drivers/pci/endpoint/functions/pci-epf-vntb.c | 136 ++++++++++++++++--
> 2 files changed, 160 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/ntb/hw/epf/ntb_hw_epf.c b/drivers/ntb/hw/epf/ntb_hw_epf.c
> index d3ecf25a5162..126ba38e32ea 100644
> --- a/drivers/ntb/hw/epf/ntb_hw_epf.c
> +++ b/drivers/ntb/hw/epf/ntb_hw_epf.c
> @@ -30,18 +30,22 @@
> #define NTB_EPF_LINK_STATUS 0x0A
> #define LINK_STATUS_UP BIT(0)
>
> -#define NTB_EPF_TOPOLOGY 0x0C
> +/* 0x24 (32bit) is unused */
> +#define NTB_EPF_CTRL_VERSION 0x0C
> #define NTB_EPF_LOWER_ADDR 0x10
> #define NTB_EPF_UPPER_ADDR 0x14
> #define NTB_EPF_LOWER_SIZE 0x18
> #define NTB_EPF_UPPER_SIZE 0x1C
> #define NTB_EPF_MW_COUNT 0x20
> -#define NTB_EPF_MW1_OFFSET 0x24
> #define NTB_EPF_SPAD_OFFSET 0x28
> #define NTB_EPF_SPAD_COUNT 0x2C
> #define NTB_EPF_DB_ENTRY_SIZE 0x30
> #define NTB_EPF_DB_DATA(n) (0x34 + (n) * 4)
> #define NTB_EPF_DB_OFFSET(n) (0xB4 + (n) * 4)
> +#define NTB_EPF_MW_OFFSET(n) (0x134 + (n) * 4)
> +#define NTB_EPF_MW_SIZE(n) (0x144 + (n) * 4)
> +
> +#define NTB_EPF_CTRL_VERSION_V1 1
>
> #define NTB_EPF_MIN_DB_COUNT 3
> #define NTB_EPF_MAX_DB_COUNT 31
> @@ -451,11 +455,12 @@ static int ntb_epf_peer_mw_get_addr(struct ntb_dev *ntb, int idx,
> phys_addr_t *base, resource_size_t *size)
> {
> struct ntb_epf_dev *ndev = ntb_ndev(ntb);
> - u32 offset = 0;
> + resource_size_t bar_sz;
> + u32 offset, sz;
> int bar;
>
> - if (idx == 0)
> - offset = readl(ndev->ctrl_reg + NTB_EPF_MW1_OFFSET);
> + offset = readl(ndev->ctrl_reg + NTB_EPF_MW_OFFSET(idx));
> + sz = readl(ndev->ctrl_reg + NTB_EPF_MW_SIZE(idx));
>
> bar = ntb_epf_mw_to_bar(ndev, idx);
> if (bar < 0)
> @@ -464,8 +469,11 @@ static int ntb_epf_peer_mw_get_addr(struct ntb_dev *ntb, int idx,
> if (base)
> *base = pci_resource_start(ndev->ntb.pdev, bar) + offset;
>
> - if (size)
> - *size = pci_resource_len(ndev->ntb.pdev, bar) - offset;
> + if (size) {
> + bar_sz = pci_resource_len(ndev->ntb.pdev, bar);
> + *size = sz ? min_t(resource_size_t, sz, bar_sz - offset)
> + : (bar_sz > offset ? bar_sz - offset : 0);
> + }
>
> return 0;
> }
> @@ -547,6 +555,24 @@ static inline void ntb_epf_init_struct(struct ntb_epf_dev *ndev,
> ndev->ntb.ops = &ntb_epf_ops;
> }
>
> +static int ntb_epf_check_version(struct ntb_epf_dev *ndev)
> +{
> + struct device *dev = ndev->dev;
> + u32 ver;
> +
> + ver = readl(ndev->ctrl_reg + NTB_EPF_CTRL_VERSION);
> +
> + switch (ver) {
> + case NTB_EPF_CTRL_VERSION_V1:
> + break;
> + default:
> + dev_err(dev, "Unsupported NTB EPF version %u\n", ver);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> static int ntb_epf_init_dev(struct ntb_epf_dev *ndev)
> {
> struct device *dev = ndev->dev;
> @@ -695,6 +721,10 @@ static int ntb_epf_pci_probe(struct pci_dev *pdev,
> return ret;
> }
>
> + ret = ntb_epf_check_version(ndev);
> + if (ret)
> + return ret;
> +
> ret = ntb_epf_init_dev(ndev);
> if (ret) {
> dev_err(dev, "Failed to init device\n");
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index 56aab5d354d6..4dfb3e40dffa 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>
>
> @@ -61,6 +62,7 @@ static struct workqueue_struct *kpcintb_workqueue;
>
> #define LINK_STATUS_UP BIT(0)
>
> +#define CTRL_VERSION 1
> #define SPAD_COUNT 64
> #define DB_COUNT 4
> #define NTB_MW_OFFSET 2
> @@ -107,7 +109,7 @@ struct epf_ntb_ctrl {
> u32 argument;
> u16 command_status;
> u16 link_status;
> - u32 topology;
> + u32 version;
> u64 addr;
> u64 size;
> u32 num_mws;
> @@ -117,6 +119,8 @@ struct epf_ntb_ctrl {
> u32 db_entry_size;
> u32 db_data[MAX_DB_COUNT];
> u32 db_offset[MAX_DB_COUNT];
> + u32 mw_offset[MAX_MW];
> + u32 mw_size[MAX_MW];
> } __packed;
>
> struct epf_ntb {
> @@ -128,6 +132,7 @@ 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;
> @@ -454,10 +459,13 @@ static int epf_ntb_config_spad_bar_alloc(struct epf_ntb *ntb)
> ntb->reg = base;
>
> ctrl = ntb->reg;
> + ctrl->version = CTRL_VERSION;
> ctrl->spad_offset = ctrl_size;
>
> 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 +697,31 @@ 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 +737,12 @@ 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 +751,31 @@ 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;
> }
>
> @@ -1040,6 +1080,60 @@ 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, "%llu\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) \
> @@ -1110,6 +1204,14 @@ 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)
> @@ -1130,6 +1232,10 @@ 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);
> @@ -1148,6 +1254,10 @@ 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,
> --
> 2.51.0
>
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