Re: [PATCH v4 1/5] cxl/mbox: Add GET_POISON_LIST mailbox command

From: Alison Schofield
Date: Fri Jan 06 2023 - 11:56:20 EST

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On Thu, Dec 15, 2022 at 01:17:43PM -0800, alison.schofield@xxxxxxxxx wrote:
> From: Alison Schofield <alison.schofield@xxxxxxxxx>
>
> CXL devices maintain a list of locations that are poisoned or result
> in poison if the addresses are accessed by the host.
>
> Per the spec (CXL 3.0 8.2.9.8.4.1), the device returns this Poison
> list as a set of Media Error Records that include the source of the
> error, the starting device physical address and length. The length is
> the number of adjacent DPAs in the record and is in units of 64 bytes.
>
> Retrieve the poison list.
>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> Signed-off-by: Alison Schofield <alison.schofield@xxxxxxxxx>
> ---
> drivers/cxl/core/mbox.c | 75 +++++++++++++++++++++++++++++++++++++++++
> drivers/cxl/cxlmem.h | 67 ++++++++++++++++++++++++++++++++++++
> drivers/cxl/pci.c | 4 +++
> 3 files changed, 146 insertions(+)
>
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index b03fba212799..dfe24a2adfdb 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -4,7 +4,9 @@
> #include <linux/security.h>
> #include <linux/debugfs.h>
> #include <linux/mutex.h>
> +#include <asm/unaligned.h>
> #include <cxlmem.h>
> +#include <cxlpci.h>
> #include <cxl.h>
>
> #include "core.h"
> @@ -770,6 +772,7 @@ int cxl_dev_state_identify(struct cxl_dev_state *cxlds)
> /* See CXL 2.0 Table 175 Identify Memory Device Output Payload */
> struct cxl_mbox_identify id;
> struct cxl_mbox_cmd mbox_cmd;
> + u32 val;
> int rc;
>
> mbox_cmd = (struct cxl_mbox_cmd) {
> @@ -793,6 +796,11 @@ int cxl_dev_state_identify(struct cxl_dev_state *cxlds)
> cxlds->lsa_size = le32_to_cpu(id.lsa_size);
> memcpy(cxlds->firmware_version, id.fw_revision, sizeof(id.fw_revision));
>
> + if (test_bit(CXL_MEM_COMMAND_ID_GET_POISON, cxlds->enabled_cmds)) {
> + val = get_unaligned_le24(id.poison_list_max_mer);
> + cxlds->poison.max_mer = min_t(u32, val, CXL_POISON_LIST_MAX);
> + }
> +
> return 0;
> }
> EXPORT_SYMBOL_NS_GPL(cxl_dev_state_identify, CXL);
> @@ -857,6 +865,73 @@ int cxl_mem_create_range_info(struct cxl_dev_state *cxlds)
> }
> EXPORT_SYMBOL_NS_GPL(cxl_mem_create_range_info, CXL);
>
> +int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
> + struct cxl_region *cxlr)
> +{
> + struct cxl_dev_state *cxlds = cxlmd->cxlds;
> + struct cxl_poison_state *cxlps = &cxlds->poison;
> + struct cxl_mbox_poison_payload_out *po;
> + struct cxl_mbox_poison_payload_in pi;
> + struct cxl_mbox_cmd mbox_cmd;
> + int nr_records = 0;
> + int rc;
> +
> + rc = mutex_lock_interruptible(&cxlps->getpoison_lock);
> + if (rc)
> + return rc;
> +
> + po = cxlps->getpoison_po;
> + pi.offset = cpu_to_le64(offset);
> + pi.length = cpu_to_le64(len / CXL_POISON_LEN_MULT);
> +
> + mbox_cmd = (struct cxl_mbox_cmd) {
> + .opcode = CXL_MBOX_OP_GET_POISON,
> + .size_in = sizeof(pi),
> + .payload_in = &pi,
> + .size_out = cxlds->payload_size,
> + .payload_out = po,
> + /* At least flags, overflow_t, and count must be valid */
> + .min_out = 12,

I see a better/righter way to do this after reviewing Ira's Process
event logs patchset.

Replace the open code of min_out with:
.min_out = struct_size(po, record, 0),

That also makes it 'righter' because the previous calculation of '12'
did not include the reserve field before the records.

So - I'm going to roll this patchset, at least for this change - but
will hold off a while pending other review comments.

Alison

> + };
> +
> + do {
> + rc = cxl_internal_send_cmd(cxlds, &mbox_cmd);
> + if (rc)
> + break;
> +
> + /* TODO TRACE the media error records */
> +
> + /* Protect against an uncleared _FLAG_MORE */
> + nr_records = nr_records + le16_to_cpu(po->count);
> + if (nr_records >= cxlps->max_mer) {
> + dev_dbg(&cxlmd->dev, "Max Error Records reached: %d\n",
> + nr_records);
> + break;
> + }
> + } while (po->flags & CXL_POISON_FLAG_MORE);
> +
> + mutex_unlock(&cxlps->getpoison_lock);
> + return rc;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_mem_get_poison, CXL);
> +
> +int cxl_poison_state_init(struct cxl_dev_state *cxlds)
> +{
> + struct cxl_poison_state *cxlps = &cxlds->poison;
> +
> + if (!test_bit(CXL_MEM_COMMAND_ID_GET_POISON, cxlds->enabled_cmds))
> + return 0;
> +
> + cxlps->getpoison_po = devm_kzalloc(cxlds->dev, cxlds->payload_size,
> + GFP_KERNEL);
> + if (!cxlps->getpoison_po)
> + return -ENOMEM;
> +
> + mutex_init(&cxlps->getpoison_lock);
> + return 0;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_poison_state_init, CXL);
> +
> struct cxl_dev_state *cxl_dev_state_create(struct device *dev)
> {
> struct cxl_dev_state *cxlds;
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index ab138004f644..f53fae20f502 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -193,6 +193,24 @@ struct cxl_endpoint_dvsec_info {
> struct range dvsec_range[2];
> };
>
> +/**
> + * struct cxl_poison_state - Poison list retrieval
> + *
> + * @max_mer: Maximum media error records held in device cache
> + * @getpoison_po: The poison list payload returned by device
> + * @getpoison_lock: Protect reads of the poison list
> + *
> + * Reads of the poison list are synchronized to ensure that a reader
> + * does not get an incomplete list because their request overlapped
> + * (was interrupted or preceded by) another read request of the same
> + * DPA range. CXL Spec 3.0 Section 8.2.9.8.4.1
> + */
> +struct cxl_poison_state {
> + u32 max_mer;
> + void *getpoison_po;
> + struct mutex getpoison_lock; /* Protect reads of poison list */
> +};
> +
> /**
> * struct cxl_dev_state - The driver device state
> *
> @@ -211,6 +229,7 @@ struct cxl_endpoint_dvsec_info {
> * (CXL 2.0 8.2.9.5.1.1 Identify Memory Device)
> * @mbox_mutex: Mutex to synchronize mailbox access.
> * @firmware_version: Firmware version for the memory device.
> + * @poison: Poison list retrieval
> * @enabled_cmds: Hardware commands found enabled in CEL.
> * @exclusive_cmds: Commands that are kernel-internal only
> * @dpa_res: Overall DPA resource tree for the device
> @@ -245,6 +264,7 @@ struct cxl_dev_state {
> size_t lsa_size;
> struct mutex mbox_mutex; /* Protects device mailbox and firmware */
> char firmware_version[0x10];
> + struct cxl_poison_state poison;
> DECLARE_BITMAP(enabled_cmds, CXL_MEM_COMMAND_ID_MAX);
> DECLARE_BITMAP(exclusive_cmds, CXL_MEM_COMMAND_ID_MAX);
>
> @@ -372,6 +392,50 @@ struct cxl_mbox_set_partition_info {
>
> #define CXL_SET_PARTITION_IMMEDIATE_FLAG BIT(0)
>
> +/* Get Poison List CXL 3.0 Spec 8.2.9.8.4.1 */
> +struct cxl_mbox_poison_payload_in {
> + __le64 offset;
> + __le64 length;
> +} __packed;
> +
> +struct cxl_mbox_poison_payload_out {
> + u8 flags;
> + u8 rsvd1;
> + __le64 overflow_t;
> + __le16 count;
> + u8 rsvd2[20];
> + struct cxl_poison_record {
> + __le64 address;
> + __le32 length;
> + __le32 rsvd;
> + } __packed record[];
> +} __packed;
> +
> +/*
> + * Get Poison List address field encodes the starting
> + * address of poison, and the source of the poison.
> + */
> +#define CXL_POISON_START_MASK GENMASK_ULL(63, 6)
> +#define CXL_POISON_SOURCE_MASK GENMASK(2, 0)
> +
> +/* Get Poison List record length is in units of 64 bytes */
> +#define CXL_POISON_LEN_MULT 64
> +
> +/* Kernel defined maximum for a list of poison errors */
> +#define CXL_POISON_LIST_MAX 1024
> +
> +/* Get Poison List: Payload out flags */
> +#define CXL_POISON_FLAG_MORE BIT(0)
> +#define CXL_POISON_FLAG_OVERFLOW BIT(1)
> +#define CXL_POISON_FLAG_SCANNING BIT(2)
> +
> +/* Get Poison List: Poison Source */
> +#define CXL_POISON_SOURCE_UNKNOWN 0
> +#define CXL_POISON_SOURCE_EXTERNAL 1
> +#define CXL_POISON_SOURCE_INTERNAL 2
> +#define CXL_POISON_SOURCE_INJECTED 3
> +#define CXL_POISON_SOURCE_VENDOR 7
> +
> /**
> * struct cxl_mem_command - Driver representation of a memory device command
> * @info: Command information as it exists for the UAPI
> @@ -441,6 +505,9 @@ int cxl_mem_create_range_info(struct cxl_dev_state *cxlds);
> struct cxl_dev_state *cxl_dev_state_create(struct device *dev);
> void set_exclusive_cxl_commands(struct cxl_dev_state *cxlds, unsigned long *cmds);
> void clear_exclusive_cxl_commands(struct cxl_dev_state *cxlds, unsigned long *cmds);
> +int cxl_poison_state_init(struct cxl_dev_state *cxlds);
> +int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
> + struct cxl_region *cxlr);
> #ifdef CONFIG_CXL_SUSPEND
> void cxl_mem_active_inc(void);
> void cxl_mem_active_dec(void);
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 3a66aadb4df0..d21357f3eca0 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -482,6 +482,10 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> if (rc)
> return rc;
>
> + rc = cxl_poison_state_init(cxlds);
> + if (rc)
> + return rc;
> +
> rc = cxl_dev_state_identify(cxlds);
> if (rc)
> return rc;
> --
> 2.37.3
>

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