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Message-ID: <84e3cd1b-019d-411a-9acd-f03aac1f1aa5@amd.com>
Date: Fri, 22 Nov 2024 14:44:38 -0600
From: Ben Cheatham <benjamin.cheatham@....com>
To: <alejandro.lucero-palau@....com>
CC: <linux-cxl@...r.kernel.org>, <netdev@...r.kernel.org>,
<dan.j.williams@...el.com>, <martin.habets@...inx.com>,
<edward.cree@....com>, <davem@...emloft.net>, <kuba@...nel.org>,
<pabeni@...hat.com>, <edumazet@...gle.com>, "Cheatham, Benjamin"
<bcheatha@....com>
Subject: Re: [PATCH v5 04/27] cxl/pci: add check for validating capabilities
On 11/18/24 10:44 AM, alejandro.lucero-palau@....com wrote:
> From: Alejandro Lucero <alucerop@....com>
>
> During CXL device initialization supported capabilities by the device
> are discovered. Type3 and Type2 devices have different mandatory
> capabilities and a Type2 expects a specific set including optional
> capabilities.
>
> Add a function for checking expected capabilities against those found
> during initialization. Allow those mandatory/expected capabilities to
> be a subset of the capabilities found.
>
> Rely on this function for validating capabilities instead of when CXL
> regs are probed.
>
> Signed-off-by: Alejandro Lucero <alucerop@....com>
> ---
> drivers/cxl/core/pci.c | 22 ++++++++++++++++++++++
> drivers/cxl/core/regs.c | 9 ---------
> drivers/cxl/pci.c | 24 ++++++++++++++++++++++++
> include/cxl/cxl.h | 6 +++++-
> 4 files changed, 51 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index ff266e91ea71..a1942b7be0bc 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -8,6 +8,7 @@
> #include <linux/pci.h>
> #include <linux/pci-doe.h>
> #include <linux/aer.h>
> +#include <cxl/cxl.h>
> #include <cxlpci.h>
> #include <cxlmem.h>
> #include <cxl.h>
> @@ -1055,3 +1056,24 @@ int cxl_pci_get_bandwidth(struct pci_dev *pdev, struct access_coordinate *c)
>
> return 0;
> }
> +
> +bool cxl_pci_check_caps(struct cxl_dev_state *cxlds, unsigned long *expected_caps,
> + unsigned long *current_caps, bool is_subset)
> +{
> + DECLARE_BITMAP(subset, CXL_MAX_CAPS);
> +
> + if (current_caps)
> + bitmap_copy(current_caps, cxlds->capabilities, CXL_MAX_CAPS);
> +
> + dev_dbg(cxlds->dev, "Checking cxlds caps 0x%08lx vs expected caps 0x%08lx\n",
> + *cxlds->capabilities, *expected_caps);
> +
> + /* Checking a minimum of mandatory capabilities? */
> + if (is_subset) {
> + bitmap_and(subset, cxlds->capabilities, expected_caps, CXL_MAX_CAPS);
> + return bitmap_equal(subset, expected_caps, CXL_MAX_CAPS);
It looks like there's a function called bitmap_subset(), does that not do the above? I didn't
look at the function since it's the end of the day when I'm writing this and my brain is tired,
but I'd rather that be used if possible. I also don't think you need this is_subset parameter and
else branch. I don't see anyone using this function where some expected capabilities are optional
and others mandatory. If that's the case then they'd probably split the calls instead.
> + } else {
> + return bitmap_equal(cxlds->capabilities, expected_caps, CXL_MAX_CAPS);
> + }
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_pci_check_caps, CXL);
> diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
> index 8287ec45b018..3b3965706414 100644
> --- a/drivers/cxl/core/regs.c
> +++ b/drivers/cxl/core/regs.c
> @@ -444,15 +444,6 @@ static int cxl_probe_regs(struct cxl_register_map *map, unsigned long *caps)
> case CXL_REGLOC_RBI_MEMDEV:
> dev_map = &map->device_map;
> cxl_probe_device_regs(host, base, dev_map, caps);
> - if (!dev_map->status.valid || !dev_map->mbox.valid ||
> - !dev_map->memdev.valid) {
> - dev_err(host, "registers not found: %s%s%s\n",
> - !dev_map->status.valid ? "status " : "",
> - !dev_map->mbox.valid ? "mbox " : "",
> - !dev_map->memdev.valid ? "memdev " : "");
> - return -ENXIO;
> - }
> -
> dev_dbg(host, "Probing device registers...\n");
> break;
> default:
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 528d4ca79fd1..5de1473a79da 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -813,6 +813,8 @@ static int cxl_pci_type3_init_mailbox(struct cxl_dev_state *cxlds)
> static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> {
> struct pci_host_bridge *host_bridge = pci_find_host_bridge(pdev->bus);
> + DECLARE_BITMAP(expected, CXL_MAX_CAPS);
> + DECLARE_BITMAP(found, CXL_MAX_CAPS);
> struct cxl_memdev_state *mds;
> struct cxl_dev_state *cxlds;
> struct cxl_register_map map;
> @@ -874,6 +876,28 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> if (rc)
> dev_dbg(&pdev->dev, "Failed to map RAS capability.\n");
>
> + bitmap_clear(expected, 0, CXL_MAX_CAPS);
> +
> + /*
> + * These are the mandatory capabilities for a Type3 device.
> + * Only checking capabilities used by current Linux drivers.
> + */
> + bitmap_set(expected, CXL_DEV_CAP_HDM, 1);
> + bitmap_set(expected, CXL_DEV_CAP_DEV_STATUS, 1);
> + bitmap_set(expected, CXL_DEV_CAP_MAILBOX_PRIMARY, 1);
> + bitmap_set(expected, CXL_DEV_CAP_DEV_STATUS, 1);
> +
> + /*
> + * Checking mandatory caps are there as, at least, a subset of those
> + * found.
> + */
> + if (!cxl_pci_check_caps(cxlds, expected, found, true)) {
> + dev_err(&pdev->dev,
> + "Expected mandatory capabilities not found: (%08lx - %08lx)\n",
> + *expected, *found);
> + return -ENXIO;
> + }
> +
> rc = cxl_pci_type3_init_mailbox(cxlds);
> if (rc)
> return rc;
> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
> index dcc9ec8a0aec..ab243ab8024f 100644
> --- a/include/cxl/cxl.h
> +++ b/include/cxl/cxl.h
> @@ -39,7 +39,7 @@ enum cxl_dev_cap {
> CXL_DEV_CAP_DEV_STATUS,
> CXL_DEV_CAP_MAILBOX_PRIMARY,
> CXL_DEV_CAP_MEMDEV,
> - CXL_MAX_CAPS = 32
> + CXL_MAX_CAPS = 64
> };
>
> struct cxl_dev_state *cxl_accel_state_create(struct device *dev);
> @@ -48,4 +48,8 @@ void cxl_set_dvsec(struct cxl_dev_state *cxlds, u16 dvsec);
> void cxl_set_serial(struct cxl_dev_state *cxlds, u64 serial);
> int cxl_set_resource(struct cxl_dev_state *cxlds, struct resource res,
> enum cxl_resource);
> +bool cxl_pci_check_caps(struct cxl_dev_state *cxlds,
> + unsigned long *expected_caps,
> + unsigned long *current_caps,
> + bool is_subset);
> #endif
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