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cxl/core: Fix potential payload size confusion in cxl_mem_get_poison()

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A recent change to cxl_mem_get_records_log() [1] highlighted a subtle
nuance of looping calls to cxl_internal_send_cmd(), i.e. that
cxl_internal_send_cmd() modifies the 'size_out' member of the @mbox_cmd
argument. That mechanism is useful for communicating underflow, but it
is unwanted when reusing @mbox_cmd for a subsequent submission. It turns
out that cxl_xfer_log() avoids this scenario by always redefining
@mbox_cmd each iteration.

Update cxl_mem_get_records_log() and cxl_mem_get_poison() to follow the
same style as cxl_xfer_log(), i.e. re-define @mbox_cmd each iteration.
The cxl_mem_get_records_log() change is just a style fixup, but the
cxl_mem_get_poison() change is a potential fix, per Alison [2]:

    Poison list retrieval can hit this case if the MORE flag is set and
    a follow on read of the list delivers more records than the previous
    read.  ie. device gives one record, sets the _MORE flag, then gives 5.

Not an urgent fix since this behavior has not been seen in the wild,
but worth tracking as a fix.

Cc: Kwangjin Ko <kwangjin.ko@sk.com>
Cc: Alison Schofield <alison.schofield@intel.com>
Fixes: ed83f7ca39 ("cxl/mbox: Add GET_POISON_LIST mailbox command")
Link: http://lore.kernel.org/r/20240402081404.1106-2-kwangjin.ko@sk.com [1]
Link: http://lore.kernel.org/r/ZhAhAL/GOaWFrauw@aschofie-mobl2 [2]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://lore.kernel.org/r/171235441633.2716581.12330082428680958635.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
This commit is contained in:
Dan Williams 2024-04-05 15:00:16 -07:00 committed by Dave Jiang
parent ed30a4a51b
commit 4b759dd576
1 changed files with 17 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
drivers/cxl/core/mbox.c
View File

@ -946,25 +946,22 @@ static void cxl_mem_get_records_log(struct cxl_memdev_state *mds,
struct cxl_memdev *cxlmd = mds->cxlds.cxlmd;
struct device *dev = mds->cxlds.dev;
struct cxl_get_event_payload *payload;
struct cxl_mbox_cmd mbox_cmd;
u8 log_type = type;
u16 nr_rec;
mutex_lock(&mds->event.log_lock);
payload = mds->event.buf;
mbox_cmd = (struct cxl_mbox_cmd) {
.opcode = CXL_MBOX_OP_GET_EVENT_RECORD,
.payload_in = &log_type,
.size_in = sizeof(log_type),
.payload_out = payload,
.min_out = struct_size(payload, records, 0),
};
do {
int rc, i;
mbox_cmd.size_out = mds->payload_size;
struct cxl_mbox_cmd mbox_cmd = (struct cxl_mbox_cmd) {
.opcode = CXL_MBOX_OP_GET_EVENT_RECORD,
.payload_in = &log_type,
.size_in = sizeof(log_type),
.payload_out = payload,
.size_out = mds->payload_size,
.min_out = struct_size(payload, records, 0),
};
rc = cxl_internal_send_cmd(mds, &mbox_cmd);
if (rc) {
@ -1297,7 +1294,6 @@ int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
struct cxl_mbox_poison_out *po;
struct cxl_mbox_poison_in pi;
struct cxl_mbox_cmd mbox_cmd;
int nr_records = 0;
int rc;
@ -1309,16 +1305,16 @@ int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
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 = mds->payload_size,
.payload_out = po,
.min_out = struct_size(po, record, 0),
};
do {
struct cxl_mbox_cmd mbox_cmd = (struct cxl_mbox_cmd){
.opcode = CXL_MBOX_OP_GET_POISON,
.size_in = sizeof(pi),
.payload_in = &pi,
.size_out = mds->payload_size,
.payload_out = po,
.min_out = struct_size(po, record, 0),
};
rc = cxl_internal_send_cmd(mds, &mbox_cmd);
if (rc)
break;