Re: [PATCH] wifi: ath11k: fix qmi memory allocation logic for CALDB region

[Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>]

On 12/8/2025 3:38 PM, Vasanthakumar Thiagarajan wrote:
> 
> 
> On 12/6/2025 11:28 PM, Alexandru Gagniuc wrote:
>> Memory region assignment in ath11k_qmi_assign_target_mem_chunk()
>> assumes that:
>>    1. firmware will make a HOST_DDR_REGION_TYPE request, and
>>    2. this request is processed before CALDB_MEM_REGION_TYPE
>>
>> In this case CALDB_MEM_REGION_TYPE, can safely be assigned immediately
>> after the host region.
>>
>> However, if the HOST_DDR_REGION_TYPE request is not made, or the
> 
> AFAICT, this is highly unlikely as HOST_DDR_REGION_TYPE will always be before
> CALDB_MEM_REGION_TYPE. >
>> reserved-memory node is not present, then res.start and res.end are 0,
>> and host_ddr_sz remains uninitialized. The physical address should
>> fall back to ATH11K_QMI_CALDB_ADDRESS. That doesn't happen:
>>
>> resource_size(&res) returns 1 for an empty resource, and thus the if
>> clause never takes the fallback path. ab->qmi.target_mem[idx].paddr
>> is assigned the uninitialized value of host_ddr_sz + 0 (res.start).
>>
>> Use "if (res.end > res.start)" for the predicate, which correctly
>> falls back to ATH11K_QMI_CALDB_ADDRESS.
>>
>> Fixes: 900730dc4705 ("wifi: ath: Use of_reserved_mem_region_to_resource() for 
>> "memory-region"")
>>
>> Cc: stable@vger.kernel.org # v6.18
>> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
>> ---
>>   drivers/net/wireless/ath/ath11k/qmi.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/wireless/ath/ath11k/qmi.c b/drivers/net/wireless/ath/ath11k/qmi.c
>> index aea56c38bf8f3..6cc26d1c1e2a4 100644
>> --- a/drivers/net/wireless/ath/ath11k/qmi.c
>> +++ b/drivers/net/wireless/ath/ath11k/qmi.c
>> @@ -2054,7 +2054,7 @@ static int ath11k_qmi_assign_target_mem_chunk(struct ath11k_base *ab)
>>                   return ret;
>>               }
>> -            if (res.end - res.start + 1 < ab->qmi.target_mem[i].size) {
>> +            if (resource_size(&res) < ab->qmi.target_mem[i].size) {
>>                   ath11k_dbg(ab, ATH11K_DBG_QMI,
>>                          "fail to assign memory of sz\n");
>>                   return -EINVAL;
>> @@ -2086,7 +2086,7 @@ static int ath11k_qmi_assign_target_mem_chunk(struct ath11k_base *ab)
>>               }
>>               if (ath11k_core_coldboot_cal_support(ab)) {
>> -                if (resource_size(&res)) {
>> +                if (res.end > res.start) {
>>                       ab->qmi.target_mem[idx].paddr =
>>                               res.start + host_ddr_sz;
>>                       ab->qmi.target_mem[idx].iaddr =
> 
> The rest looks good.
> 
> Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
> 

Well, since CALDB_MEM_REGION_TYPE will always come only after HOST_DDR_REGION_TYPE we'll 
not be running into this issue in real deployment with ath11k firmware binaries available 
in public.