Hi,
On Fri, Jul 16, 2021 at 4:48 AM Vikas Gupta <vikas.gupta@xxxxxxxxxxxx> wrote:
>
> Hi Allen/Tyler,
> The patch looks good to me.
Thanks.
Rafal, is it OK if I include this patch together with the rest of the
patches in this patch set in a pull request to arm-soc?
Thanks,
Jens
>
> Thanks,
> Vikas
>
>>
>> > From: Allen Pais <apais@xxxxxxxxxxxxxxxxxxx>
>> >
>> > Implement a .shutdown hook that will be called during a kexec operation
>> > so that the TEE shared memory, session, and context that were set up
>> > during .probe can be properly freed/closed.
>> >
>> > Additionally, don't use dma-buf backed shared memory for the
>> > fw_shm_pool. dma-buf backed shared memory cannot be reliably freed and
>> > unregistered during a kexec operation even when tee_shm_free() is called
>> > on the shm from a .shutdown hook. The problem occurs because
>> > dma_buf_put() calls fput() which then uses task_work_add(), with the
>> > TWA_RESUME parameter, to queue tee_shm_release() to be called before the
>> > current task returns to user mode. However, the current task never
>> > returns to user mode before the kexec completes so the memory is never
>> > freed nor unregistered.
>> >
>> > Use tee_shm_alloc_kernel_buf() to avoid dma-buf backed shared memory
>> > allocation so that tee_shm_free() can directly call tee_shm_release().
>> > This will ensure that the shm can be freed and unregistered during a
>> > kexec operation.
>> >
>> > Fixes: 246880958ac9 ("firmware: broadcom: add OP-TEE based BNXT f/w manager")
>> > Cc: stable@xxxxxxxxxxxxxxx
>> > Signed-off-by: Allen Pais <apais@xxxxxxxxxxxxxxxxxxx>
>> > Co-developed-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>
>> > Signed-off-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>
>> > ---
>> > drivers/firmware/broadcom/tee_bnxt_fw.c | 14 +++++++++++---
>> > 1 file changed, 11 insertions(+), 3 deletions(-)
>> >
>> > diff --git a/drivers/firmware/broadcom/tee_bnxt_fw.c b/drivers/firmware/broadcom/tee_bnxt_fw.c
>> > index ed10da5313e8..a5bf4c3f6dc7 100644
>> > --- a/drivers/firmware/broadcom/tee_bnxt_fw.c
>> > +++ b/drivers/firmware/broadcom/tee_bnxt_fw.c
>> > @@ -212,10 +212,9 @@ static int tee_bnxt_fw_probe(struct device *dev)
>> >
>> > pvt_data.dev = dev;
>> >
>> > - fw_shm_pool = tee_shm_alloc(pvt_data.ctx, MAX_SHM_MEM_SZ,
>> > - TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);
>> > + fw_shm_pool = tee_shm_alloc_kernel_buf(pvt_data.ctx, MAX_SHM_MEM_SZ);
>> > if (IS_ERR(fw_shm_pool)) {
>> > - dev_err(pvt_data.dev, "tee_shm_alloc failed\n");
>> > + dev_err(pvt_data.dev, "tee_shm_alloc_kernel_buf failed\n");
>> > err = PTR_ERR(fw_shm_pool);
>> > goto out_sess;
>> > }
>> > @@ -242,6 +241,14 @@ static int tee_bnxt_fw_remove(struct device *dev)
>> > return 0;
>> > }
>> >
>> > +static void tee_bnxt_fw_shutdown(struct device *dev)
>> > +{
>> > + tee_shm_free(pvt_data.fw_shm_pool);
>> > + tee_client_close_session(pvt_data.ctx, pvt_data.session_id);
>> > + tee_client_close_context(pvt_data.ctx);
>> > + pvt_data.ctx = NULL;
>> > +}
>> > +
>> > static const struct tee_client_device_id tee_bnxt_fw_id_table[] = {
>> > {UUID_INIT(0x6272636D, 0x2019, 0x0716,
>> > 0x42, 0x43, 0x4D, 0x5F, 0x53, 0x43, 0x48, 0x49)},
>> > @@ -257,6 +264,7 @@ static struct tee_client_driver tee_bnxt_fw_driver = {
>> > .bus = &tee_bus_type,
>> > .probe = tee_bnxt_fw_probe,
>> > .remove = tee_bnxt_fw_remove,
>> > + .shutdown = tee_bnxt_fw_shutdown,
>> > },
>> > };
>> >
>> > --
>> > 2.25.1
>> >
>>
>> ----- End forwarded message -----
