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

[Vasanthakumar Thiagarajan]

On 12/8/2025 3:55 PM, Vasanthakumar Thiagarajan wrote:
> 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@xxxxxxxxxxxxxxx # v6.18
> > > Signed-off-by: Alexandru Gagniuc <mr.nuke.me@xxxxxxxxx>
> > > ---
> > >   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@xxxxxxxxxxxxxxxx>
>
> 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.

Nevertheless, I agree this is a critical issue to be fixed. There is another patch[1]
fixing the same issue a bit differently.


Vasanth

[1]: https://lore.kernel.org/linux-wireless/20251208200437.14199-1-ansuelsmth@xxxxxxxxx/