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Message-ID: <20230829154945.00002870@Huawei.com>
Date: Tue, 29 Aug 2023 15:49:45 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Ira Weiny <ira.weiny@...el.com>
CC: Dan Williams <dan.j.williams@...el.com>,
Navneet Singh <navneet.singh@...el.com>,
Fan Ni <fan.ni@...sung.com>,
Davidlohr Bueso <dave@...olabs.net>,
Dave Jiang <dave.jiang@...el.com>,
Alison Schofield <alison.schofield@...el.com>,
Vishal Verma <vishal.l.verma@...el.com>,
<linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC v2 05/18] cxl/port: Add Dynamic Capacity mode
support to endpoint decoders
On Mon, 28 Aug 2023 22:20:56 -0700
Ira Weiny <ira.weiny@...el.com> wrote:
> Endpoint decoders used to map Dynamic Capacity must be configured to
> point to the correct Dynamic Capacity (DC) Region. The decoder mode
> currently represents the partition the decoder points to such as ram or
> pmem.
>
> Expand the mode to include DC Regions.
>
> Co-developed-by: Navneet Singh <navneet.singh@...el.com>
> Signed-off-by: Navneet Singh <navneet.singh@...el.com>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
I'm reading this in a linear fashion for now (and ideally that should
always make sense) so I don't currently see the reason for the loops
in here. If they are needed for a future patch, add something to the
description to indicate that.
>
> ---
> Changes for v2:
> [iweiny: split from region creation patch]
> ---
> Documentation/ABI/testing/sysfs-bus-cxl | 19 ++++++++++---------
> drivers/cxl/core/hdm.c | 24 ++++++++++++++++++++++++
> drivers/cxl/core/port.c | 16 ++++++++++++++++
> 3 files changed, 50 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
> index 6350dd82b9a9..2268ffcdb604 100644
> --- a/Documentation/ABI/testing/sysfs-bus-cxl
> +++ b/Documentation/ABI/testing/sysfs-bus-cxl
> @@ -257,22 +257,23 @@ Description:
>
> What: /sys/bus/cxl/devices/decoderX.Y/mode
> Date: May, 2022
> -KernelVersion: v6.0
> +KernelVersion: v6.0, v6.6 (dcY)
> Contact: linux-cxl@...r.kernel.org
> Description:
> (RW) When a CXL decoder is of devtype "cxl_decoder_endpoint" it
> translates from a host physical address range, to a device local
> address range. Device-local address ranges are further split
> - into a 'ram' (volatile memory) range and 'pmem' (persistent
> - memory) range. The 'mode' attribute emits one of 'ram', 'pmem',
> - 'mixed', or 'none'. The 'mixed' indication is for error cases
> - when a decoder straddles the volatile/persistent partition
> - boundary, and 'none' indicates the decoder is not actively
> - decoding, or no DPA allocation policy has been set.
> + into a 'ram' (volatile memory) range, 'pmem' (persistent
> + memory) range, or Dynamic Capacity (DC) range. The 'mode'
> + attribute emits one of 'ram', 'pmem', 'dcY', 'mixed', or
> + 'none'. The 'mixed' indication is for error cases when a
> + decoder straddles the volatile/persistent partition boundary,
> + and 'none' indicates the decoder is not actively decoding, or
> + no DPA allocation policy has been set.
>
> 'mode' can be written, when the decoder is in the 'disabled'
> - state, with either 'ram' or 'pmem' to set the boundaries for the
> - next allocation.
> + state, with 'ram', 'pmem', or 'dcY' to set the boundaries for
> + the next allocation.
>
>
> What: /sys/bus/cxl/devices/decoderX.Y/dpa_resource
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index a254f79dd4e8..3f4af1f5fac8 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -267,6 +267,19 @@ static void devm_cxl_dpa_release(struct cxl_endpoint_decoder *cxled)
> __cxl_dpa_release(cxled);
> }
>
> +static int dc_mode_to_region_index(enum cxl_decoder_mode mode)
> +{
> + int index = 0;
> +
> + for (int i = CXL_DECODER_DC0; i <= CXL_DECODER_DC7; i++) {
As you are relying on them being in order and adjacent for the loop, why is
if (mode < CXL_DECODER_DC0 || mode > CXL_DECODER_DC7)
return -EINVAL;
return mode - CXL_DECODER_DC0;
Not sufficient?
> + if (mode == i)
> + return index;
> + index++;
> + }
> +
> + return -EINVAL;
> +}
> +
> static int __cxl_dpa_reserve(struct cxl_endpoint_decoder *cxled,
> resource_size_t base, resource_size_t len,
> resource_size_t skipped)
> @@ -429,6 +442,7 @@ int cxl_dpa_set_mode(struct cxl_endpoint_decoder *cxled,
> switch (mode) {
> case CXL_DECODER_RAM:
> case CXL_DECODER_PMEM:
> + case CXL_DECODER_DC0 ... CXL_DECODER_DC7:
> break;
> default:
> dev_dbg(dev, "unsupported mode: %d\n", mode);
> @@ -456,6 +470,16 @@ int cxl_dpa_set_mode(struct cxl_endpoint_decoder *cxled,
> goto out;
> }
>
> + for (int i = CXL_DECODER_DC0; i <= CXL_DECODER_DC7; i++) {
> + int index = dc_mode_to_region_index(i);
> +
> + if (mode == i && !resource_size(&cxlds->dc_res[index])) {
Not obvious why we have the loop in this patch - perhaps it makes sense later.
If this is to enable later changes, then good to say that in the patch description.
otherwise, something like.
int index;
rc = dc_mode_to_region_index(i);
if (rc < 0)
goto out;
index = rc;
if (!resource_size(&cxlds->dc_res[index]) {
....
> + dev_dbg(dev, "no available dynamic capacity\n");
> + rc = -ENXIO;
> + goto out;
> + }
> + }
> +
> cxled->mode = mode;
> rc = 0;
> out:
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index f58cf01f8d2c..ce4a66865db3 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -197,6 +197,22 @@ static ssize_t mode_store(struct device *dev, struct device_attribute *attr,
> mode = CXL_DECODER_PMEM;
> else if (sysfs_streq(buf, "ram"))
> mode = CXL_DECODER_RAM;
> + else if (sysfs_streq(buf, "dc0"))
> + mode = CXL_DECODER_DC0;
> + else if (sysfs_streq(buf, "dc1"))
> + mode = CXL_DECODER_DC1;
> + else if (sysfs_streq(buf, "dc2"))
> + mode = CXL_DECODER_DC2;
> + else if (sysfs_streq(buf, "dc3"))
> + mode = CXL_DECODER_DC3;
> + else if (sysfs_streq(buf, "dc4"))
> + mode = CXL_DECODER_DC4;
> + else if (sysfs_streq(buf, "dc5"))
> + mode = CXL_DECODER_DC5;
> + else if (sysfs_streq(buf, "dc6"))
> + mode = CXL_DECODER_DC6;
> + else if (sysfs_streq(buf, "dc7"))
> + mode = CXL_DECODER_DC7;
> else
> return -EINVAL;
>
>
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