Re: [PATCH 05/12] xen/arm: ffa: Fix PARTINFO RX release errors

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi Jens,

> On 9 Feb 2026, at 15:24, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote:
> 
> Hi Bertrand,
> 
> On Tue, Feb 3, 2026 at 6:38 PM Bertrand Marquis
> <bertrand.marquis@xxxxxxx> wrote:
>> 
>> On PARTITION_INFO_GET error paths, Xen unconditionally called
>> FFA_RX_RELEASE for the SPMC RX buffer. If the SPMC didn't grant RX
>> ownership (i.e., the call failed early), this issues a spurious release
>> that returns DENIED and produces warnings.
>> 
>> Modify ffa_rxtx_spmc_rx_release() to return the release status and let
>> callers choose whether to log it. Only issue FFA_RX_RELEASE after a
>> successful PARTINFO SMC, while always releasing the local RX lock to
>> avoid deadlocks.
>> 
>> Update handle_partition_info_get() to only release the SPMC RX buffer
>> after successful fw_ret checks, and ignore release errors during the
>> error path.
>> 
>> Functional impact: eliminates spurious FFA_RX_RELEASE calls and
>> associated DENIED warnings when PARTITION_INFO_GET fails before
>> obtaining SPMC RX buffer ownership.
>> 
>> Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
>> ---
>> xen/arch/arm/tee/ffa_partinfo.c | 14 ++++++++++++--
>> xen/arch/arm/tee/ffa_private.h  |  2 +-
>> xen/arch/arm/tee/ffa_rxtx.c     | 14 +++++++++-----
>> 3 files changed, 22 insertions(+), 8 deletions(-)
>> 
>> diff --git a/xen/arch/arm/tee/ffa_partinfo.c 
>> b/xen/arch/arm/tee/ffa_partinfo.c
>> index bf906ed0c88f..6b01c4abe915 100644
>> --- a/xen/arch/arm/tee/ffa_partinfo.c
>> +++ b/xen/arch/arm/tee/ffa_partinfo.c
>> @@ -92,9 +92,11 @@ static int32_t ffa_get_sp_partinfo(struct ffa_uuid uuid, 
>> uint32_t *sp_count,
>>                                    uint32_t dst_size)
>> {
>>     int32_t ret;
>> +    int32_t release_ret;
>>     uint32_t src_size, real_sp_count;
>>     void *src_buf;
>>     uint32_t count = 0;
>> +    bool spmc_ok = false;
> 
> Wouldn't notify_fw be clearer, and the same in ffa_partinfo_init()?

Yes that would make more sense.
I will rename spmc_ok to notify_fw in v2.

> 
> Either way, please add:
> Reviewed-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>

Thanks

Cheers
Bertrand

> 
> Cheers,
> Jens
> 
>> 
>>     /* We need to use the RX buffer to receive the list */
>>     src_buf = ffa_rxtx_spmc_rx_acquire();
>> @@ -104,6 +106,7 @@ static int32_t ffa_get_sp_partinfo(struct ffa_uuid uuid, 
>> uint32_t *sp_count,
>>     ret = ffa_partition_info_get(uuid, 0, &real_sp_count, &src_size);
>>     if ( ret )
>>         goto out;
>> +    spmc_ok = true;
>> 
>>     /* Validate the src_size we got */
>>     if ( src_size < sizeof(struct ffa_partition_info_1_0) ||
>> @@ -157,7 +160,10 @@ static int32_t ffa_get_sp_partinfo(struct ffa_uuid 
>> uuid, uint32_t *sp_count,
>>     *sp_count = count;
>> 
>> out:
>> -    ffa_rxtx_spmc_rx_release();
>> +    release_ret = ffa_rxtx_spmc_rx_release(spmc_ok);
>> +    if ( release_ret )
>> +        gprintk(XENLOG_WARNING,
>> +                "ffa: Error releasing SPMC RX buffer: %d\n", release_ret);
>>     return ret;
>> }
>> 
>> @@ -507,6 +513,7 @@ bool ffa_partinfo_init(void)
>>     int32_t e;
>>     void *spmc_rx;
>>     struct ffa_uuid nil_uuid = { .val = { 0ULL, 0ULL } };
>> +    bool spmc_ok = false;
>> 
>>     if ( !ffa_fw_supports_fid(FFA_PARTITION_INFO_GET) ||
>>          !ffa_fw_supports_fid(FFA_MSG_SEND_DIRECT_REQ_32))
>> @@ -522,6 +529,7 @@ bool ffa_partinfo_init(void)
>>         printk(XENLOG_ERR "ffa: Failed to get list of SPs: %d\n", e);
>>         goto out;
>>     }
>> +    spmc_ok = true;
>> 
>>     if ( count >= FFA_MAX_NUM_SP )
>>     {
>> @@ -533,7 +541,9 @@ bool ffa_partinfo_init(void)
>>     ret = init_subscribers(spmc_rx, count, fpi_size);
>> 
>> out:
>> -    ffa_rxtx_spmc_rx_release();
>> +    e = ffa_rxtx_spmc_rx_release(spmc_ok);
>> +    if ( e )
>> +        printk(XENLOG_WARNING "ffa: Error releasing SPMC RX buffer: %d\n", 
>> e);
>>     return ret;
>> }
>> 
>> diff --git a/xen/arch/arm/tee/ffa_private.h b/xen/arch/arm/tee/ffa_private.h
>> index 58562d8e733c..461e87f6f9c4 100644
>> --- a/xen/arch/arm/tee/ffa_private.h
>> +++ b/xen/arch/arm/tee/ffa_private.h
>> @@ -458,7 +458,7 @@ int32_t ffa_endpoint_domain_lookup(uint16_t endpoint_id, 
>> struct domain **d_out,
>> bool ffa_rxtx_spmc_init(void);
>> void ffa_rxtx_spmc_destroy(void);
>> void *ffa_rxtx_spmc_rx_acquire(void);
>> -void ffa_rxtx_spmc_rx_release(void);
>> +int32_t ffa_rxtx_spmc_rx_release(bool notify_fw);
>> void *ffa_rxtx_spmc_tx_acquire(void);
>> void ffa_rxtx_spmc_tx_release(void);
>> 
>> diff --git a/xen/arch/arm/tee/ffa_rxtx.c b/xen/arch/arm/tee/ffa_rxtx.c
>> index 7d8bb4f4d031..50758fb57cdf 100644
>> --- a/xen/arch/arm/tee/ffa_rxtx.c
>> +++ b/xen/arch/arm/tee/ffa_rxtx.c
>> @@ -375,18 +375,22 @@ void *ffa_rxtx_spmc_rx_acquire(void)
>>     return NULL;
>> }
>> 
>> -void ffa_rxtx_spmc_rx_release(void)
>> +int32_t ffa_rxtx_spmc_rx_release(bool notify_fw)
>> {
>>     int32_t ret;
>> 
>>     ASSERT(spin_is_locked(&ffa_spmc_rx_lock));
>> 
>> -    /* Inform the SPMC that we are done with our RX buffer */
>> -    ret = ffa_simple_call(FFA_RX_RELEASE, 0, 0, 0, 0);
>> -    if ( ret != FFA_RET_OK )
>> -        printk(XENLOG_DEBUG "Error releasing SPMC RX buffer: %d\n", ret);
>> +    if ( notify_fw )
>> +    {
>> +        /* Inform the SPMC that we are done with our RX buffer */
>> +        ret = ffa_simple_call(FFA_RX_RELEASE, 0, 0, 0, 0);
>> +    }
>> +    else
>> +        ret = FFA_RET_OK;
>> 
>>     spin_unlock(&ffa_spmc_rx_lock);
>> +    return ret;
>> }
>> 
>> void *ffa_rxtx_spmc_tx_acquire(void)
>> --
>> 2.50.1 (Apple Git-155)