From: Frank Li <Frank.li@nxp.com>
To: Koichiro Den <den@valinux.co.jp>
Cc: "Jon Mason" <jdmason@kudzu.us>,
"Dave Jiang" <dave.jiang@intel.com>,
"Allen Hubbe" <allenbh@gmail.com>,
"Manivannan Sadhasivam" <mani@kernel.org>,
"Krzysztof Wilczyński" <kwilczynski@kernel.org>,
"Kishon Vijay Abraham I" <kishon@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Jerome Brunet" <jbrunet@baylibre.com>,
"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Niklas Cassel" <cassel@kernel.org>,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
ntb@lists.linux.dev
Subject: Re: [PATCH v4 05/12] PCI: endpoint: pci-epf-vntb: Guard configfs writes after EPC attach
Date: Thu, 14 May 2026 14:57:28 -0400 [thread overview]
Message-ID: <agYbGKfndwQnVvcA@lizhi-Precision-Tower-5810> (raw)
In-Reply-To: <20260513024923.451765-6-den@valinux.co.jp>
On Wed, May 13, 2026 at 11:49:16AM +0900, Koichiro Den wrote:
> db_count controls how many doorbell slots are allocated and exposed. It is
> also used by the doorbell mask helpers. After an EPC has been attached,
> changing it from configfs can leave runtime paths using a different count
> than the one used to set up the doorbell resources.
>
> Reject db_count writes after EPC attach, and reject values outside
> MIN_DB_COUNT..MAX_DB_COUNT before attach. Now that MIN_DB_COUNT documents
> the usable doorbell floor, use it in the store path too.
>
> While at it, apply the same after-attach guard to the other vNTB configfs
> knobs. BAR choices, spad_count, memory-window counts and sizes, and the
> virtual PCI IDs are also consumed during bind, so changing them later at
> runtime is meaningless and unsafe.
>
> Return -EOPNOTSUPP for after-attach writes. The value itself may be valid,
> but changing it in that state is not supported.
>
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---
Reviewed-by: Frank Li <Frank.Li@nxp.com>
> Changes since v3:
> - New patch.
>
> drivers/pci/endpoint/functions/pci-epf-vntb.c | 41 ++++++++++++++++++-
> 1 file changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index 818ae5999976..524355a8b4be 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> @@ -1020,6 +1020,11 @@ static void epf_ntb_epc_cleanup(struct epf_ntb *ntb)
> epf_ntb_config_sspad_bar_clear(ntb);
> }
>
> +static bool epf_ntb_epc_attached(struct epf_ntb *ntb)
> +{
> + return ntb->epf->epc || ntb->epf->sec_epc;
> +}
> +
> #define EPF_NTB_R(_name) \
> static ssize_t epf_ntb_##_name##_show(struct config_item *item, \
> char *page) \
> @@ -1039,6 +1044,9 @@ static ssize_t epf_ntb_##_name##_store(struct config_item *item, \
> u32 val; \
> int ret; \
> \
> + if (epf_ntb_epc_attached(ntb)) \
> + return -EOPNOTSUPP; \
> + \
> ret = kstrtou32(page, 0, &val); \
> if (ret) \
> return ret; \
> @@ -1081,6 +1089,9 @@ static ssize_t epf_ntb_##_name##_store(struct config_item *item, \
> u64 val; \
> int ret; \
> \
> + if (epf_ntb_epc_attached(ntb)) \
> + return -EOPNOTSUPP; \
> + \
> ret = kstrtou64(page, 0, &val); \
> if (ret) \
> return ret; \
> @@ -1119,6 +1130,9 @@ static ssize_t epf_ntb_##_name##_store(struct config_item *item, \
> int val; \
> int ret; \
> \
> + if (epf_ntb_epc_attached(ntb)) \
> + return -EOPNOTSUPP; \
> + \
> ret = kstrtoint(page, 0, &val); \
> if (ret) \
> return ret; \
> @@ -1139,6 +1153,9 @@ static ssize_t epf_ntb_num_mws_store(struct config_item *item,
> u32 val;
> int ret;
>
> + if (epf_ntb_epc_attached(ntb))
> + return -EOPNOTSUPP;
> +
> ret = kstrtou32(page, 0, &val);
> if (ret)
> return ret;
> @@ -1151,10 +1168,32 @@ static ssize_t epf_ntb_num_mws_store(struct config_item *item,
> return len;
> }
>
> +static ssize_t epf_ntb_db_count_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);
> + u32 val;
> + int ret;
> +
> + if (epf_ntb_epc_attached(ntb))
> + return -EOPNOTSUPP;
> +
> + ret = kstrtou32(page, 0, &val);
> + if (ret)
> + return ret;
> +
> + if (val < MIN_DB_COUNT || val > MAX_DB_COUNT)
> + return -EINVAL;
> +
> + WRITE_ONCE(ntb->db_count, val);
> +
> + return len;
> +}
> +
> EPF_NTB_R(spad_count)
> EPF_NTB_W(spad_count)
> EPF_NTB_R(db_count)
> -EPF_NTB_W(db_count)
> EPF_NTB_R(num_mws)
> EPF_NTB_R(vbus_number)
> EPF_NTB_W(vbus_number)
> --
> 2.51.0
>
next prev parent reply other threads:[~2026-05-14 18:57 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-13 2:49 [PATCH v4 00/12] PCI: endpoint: pci-epf-vntb / NTB: epf: Enable per-doorbell bit handling Koichiro Den
2026-05-13 2:49 ` [PATCH v4 01/12] PCI: endpoint: pci-epf-vntb: Document legacy MSI doorbell offset Koichiro Den
2026-05-13 2:49 ` [PATCH v4 02/12] PCI: endpoint: pci-epf-vntb: Defer pci_epc_raise_irq() out of atomic context Koichiro Den
2026-05-14 18:53 ` Frank Li
2026-05-13 2:49 ` [PATCH v4 03/12] PCI: endpoint: pci-epf-vntb: Report 0-based doorbell vector via ntb_db_event() Koichiro Den
2026-05-13 2:49 ` [PATCH v4 04/12] PCI: endpoint: pci-epf-vntb: Reject unusable doorbell counts Koichiro Den
2026-05-14 18:55 ` Frank Li
2026-05-13 2:49 ` [PATCH v4 05/12] PCI: endpoint: pci-epf-vntb: Guard configfs writes after EPC attach Koichiro Den
2026-05-14 18:57 ` Frank Li [this message]
2026-05-13 2:49 ` [PATCH v4 06/12] PCI: endpoint: pci-epf-vntb: Exclude reserved slots from db_valid_mask Koichiro Den
2026-05-13 2:49 ` [PATCH v4 07/12] PCI: endpoint: pci-epf-vntb: Implement db_vector_count/mask for doorbells Koichiro Den
2026-05-14 19:02 ` Frank Li
2026-05-13 2:49 ` [PATCH v4 08/12] NTB: epf: Document legacy doorbell slot offset in ntb_epf_peer_db_set() Koichiro Den
2026-05-13 2:49 ` [PATCH v4 09/12] NTB: epf: Make db_valid_mask cover only real doorbell bits Koichiro Den
2026-05-26 22:21 ` Dave Jiang
2026-05-13 2:49 ` [PATCH v4 10/12] NTB: epf: Report 0-based doorbell vector via ntb_db_event() Koichiro Den
2026-05-14 19:03 ` Frank Li
2026-05-26 22:28 ` Dave Jiang
2026-05-13 2:49 ` [PATCH v4 11/12] NTB: epf: Fix doorbell bitmask and IRQ vector handling Koichiro Den
2026-05-14 19:06 ` Frank Li
2026-05-26 22:36 ` Dave Jiang
2026-05-13 2:49 ` [PATCH v4 12/12] NTB: epf: Implement db_vector_count/mask for doorbells Koichiro Den
2026-05-26 22:47 ` Dave Jiang
2026-06-23 16:31 ` Bjorn Helgaas
2026-06-24 1:35 ` Koichiro Den
2026-05-19 14:42 ` [PATCH v4 00/12] PCI: endpoint: pci-epf-vntb / NTB: epf: Enable per-doorbell bit handling Manivannan Sadhasivam
2026-05-19 21:29 ` Dave Jiang
2026-05-21 6:29 ` Koichiro Den
2026-05-26 14:45 ` Dave Jiang
2026-05-26 15:56 ` Koichiro Den
2026-05-26 16:27 ` Dave Jiang
2026-05-27 9:09 ` Manivannan Sadhasivam
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