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drm/amd/ras: chunk UNIRAS CPER debugfs reads

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Legacy CPER ring readers can issue one debugfs read with a buffer larger
than the UNIRAS RAS command payload limit. Passing that full size to
GET_CPER_RECORD makes the command reject the request, so userspace may
only see the ring prefix and treat the CPER stream as empty.

Commit 3c88fb7aa5 ("drm/amd/ras: bound CPER record fetch buffer
size") intentionally bounds CPER record fetch allocation by the command
buffer size. Keep the debugfs ABI as a single contiguous ring read by
splitting the internal GET_CPER_RECORD requests into
RAS_CMD_MAX_CPER_BUF_SZ chunks.

Accumulate the copied payload and update the legacy header write pointers
from the total bytes returned to userspace.

Signed-off-by: Xiang Liu <xiang.liu@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Xiang Liu 2026-05-29 22:11:26 +08:00 committed by Alex Deucher
parent ff905a9b62
commit 33425e4971
1 changed files with 33 additions and 16 deletions
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49
drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
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@ -501,6 +501,8 @@ static ssize_t amdgpu_ras_cper_debugfs_read(struct file *f, char __user *buf,
u32 total_cper_num;
u64 start_cper_id;
u64 cper_offset;
size_t chunk_size;
size_t total_data_size = 0;
bool read_header;
int r;
@ -550,30 +552,45 @@ static ssize_t amdgpu_ras_cper_debugfs_read(struct file *f, char __user *buf,
if (!data_size)
return 0;
record_req->buf_ptr = (u64)(uintptr_t)data_buf;
record_req->buf_size = data_size;
record_req->cper_start_id = start_cper_id + cper_offset;
record_req->cper_num = total_cper_num - cper_offset;
r = amdgpu_ras_mgr_handle_ras_cmd(ring->adev,
RAS_CMD__GET_CPER_RECORD,
record_req, sizeof(struct ras_cmd_cper_record_req),
record_rsp, sizeof(struct ras_cmd_cper_record_rsp));
if (r)
return r;
if (record_rsp->real_data_size > data_size)
return -EIO;
while (data_size && cper_offset < total_cper_num) {
memset(record_req, 0, sizeof(*record_req));
memset(record_rsp, 0, sizeof(*record_rsp));
chunk_size = min_t(size_t, data_size, RAS_CMD_MAX_CPER_BUF_SZ);
record_req->buf_ptr = (u64)(uintptr_t)data_buf;
record_req->buf_size = chunk_size;
record_req->cper_start_id = start_cper_id + cper_offset;
record_req->cper_num = total_cper_num - cper_offset;
r = amdgpu_ras_mgr_handle_ras_cmd(ring->adev,
RAS_CMD__GET_CPER_RECORD,
record_req,
sizeof(struct ras_cmd_cper_record_req),
record_rsp,
sizeof(struct ras_cmd_cper_record_rsp));
if (r)
return r;
if (!record_rsp->real_data_size || !record_rsp->real_cper_num)
break;
if (record_rsp->real_data_size > data_size)
return -EIO;
data_buf += record_rsp->real_data_size;
data_size -= record_rsp->real_data_size;
total_data_size += record_rsp->real_data_size;
cper_offset += record_rsp->real_cper_num;
}
if (read_header) {
ring_header[1] = record_rsp->real_data_size >> 2;
ring_header[1] = total_data_size >> 2;
ring_header[2] = ring_header[1];
if (copy_to_user(buf, ring_header, ring_header_size))
return -EFAULT;
}
r = read_header ? record_rsp->real_data_size + ring_header_size :
record_rsp->real_data_size;
*offset = cper_offset + record_rsp->real_cper_num + 1;
r = read_header ? total_data_size + ring_header_size : total_data_size;
*offset = cper_offset + 1;
return r;
}