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

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Message-ID: <7ef46837-7799-4ede-9f5e-88a010d5d1d4@oss.qualcomm.com>
Date: Mon, 8 Dec 2025 18:23:46 +0800
From: Baochen Qiang <baochen.qiang@....qualcomm.com>
To: Alexandru Gagniuc <mr.nuke.me@...il.com>, jjohnson@...nel.org,
        ath11k@...ts.infradead.org, "Rob Herring (Arm)" <robh@...nel.org>,
        Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@....qualcomm.com>
Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Jeff Johnson <jeff.johnson@....qualcomm.com>
Subject: Re: [PATCH] wifi: ath11k: fix qmi memory allocation logic for CALDB
 region



On 12/7/2025 1:58 AM, 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
> 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.

In addition, does it make sense to do of_reserved_mem_region_to_resource() before the
loop, which may give CALDB_MEM_REGION_TYPE a chance even HOST_DDR_REGION_TYPE request is
not made?

> 
> Fixes: 900730dc4705 ("wifi: ath: Use of_reserved_mem_region_to_resource() for "memory-region"")
> 
> Cc: stable@...r.kernel.org # v6.18
> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@...il.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 =