linux-kernel - Re: [PATCH v5 08/12] firmware: qcom: tzmem: export shm

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Message-ID: <07cd8098-2d2e-4f90-96c0-64f8547e291f@oss.qualcomm.com>
Date: Tue, 8 Jul 2025 10:18:02 +1000
From: Amirreza Zarrabi <amirreza.zarrabi@....qualcomm.com>
To: Kuldeep Singh <quic_kuldsing@...cinc.com>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        Sumit Garg <sumit.garg@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
        Apurupa Pattapu <quic_apurupa@...cinc.com>,
        Kees Cook <kees@...nel.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>
Cc: Harshal Dev <quic_hdev@...cinc.com>, linux-arm-msm@...r.kernel.org,
        op-tee@...ts.trustedfirmware.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org, linux-doc@...r.kernel.org,
        Neil Armstrong <neil.armstrong@...aro.org>
Subject: Re: [PATCH v5 08/12] firmware: qcom: tzmem: export shm_bridge
 create/delete

Hi Kuldeep,

On 7/1/2025 9:47 PM, Kuldeep Singh wrote:
> 
> On 5/27/2025 12:26 PM, Amirreza Zarrabi wrote:
>> Anyone with access to contiguous physical memory should be able to
>> share memory with QTEE using shm_bridge.
>>
>> Tested-by: Neil Armstrong <neil.armstrong@...aro.org>
>> Signed-off-by: Amirreza Zarrabi <amirreza.zarrabi@....qualcomm.com>
>> ---
>>  drivers/firmware/qcom/qcom_tzmem.c       | 57 +++++++++++++++++++++++++-------
>>  include/linux/firmware/qcom/qcom_tzmem.h | 15 +++++++++
>>  2 files changed, 60 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/firmware/qcom/qcom_tzmem.c b/drivers/firmware/qcom/qcom_tzmem.c
>> index 4fe333fd2f07..e9e4f06924ae 100644
>> --- a/drivers/firmware/qcom/qcom_tzmem.c
>> +++ b/drivers/firmware/qcom/qcom_tzmem.c
>> @@ -108,25 +108,61 @@ static int qcom_tzmem_init(void)
>>  	return 0;
>>  }
>>  
>> -static int qcom_tzmem_init_area(struct qcom_tzmem_area *area)
>> +/**
>> + * qcom_tzmem_shm_bridge_create() - Create a SHM bridge.
>> + * @paddr: Physical address of the memory to share.
>> + * @size: Size of the memory to share.
>> + * @handle: Handle to the SHM bridge.
>> + *
>> + * On platforms that support SHM bridge, this function creates a SHM bridge
>> + * for the given memory region with QTEE. The handle returned by this function
>> + * must be passed to qcom_tzmem_shm_bridge_delete() to free the SHM bridge.
>> + *
>> + * Return: On success, returns 0; on failure, returns < 0.
>> + */
>> +int qcom_tzmem_shm_bridge_create(phys_addr_t paddr, size_t size, u64 *handle)
>>  {
>>  	u64 pfn_and_ns_perm, ipfn_and_s_perm, size_and_flags;
>> -	int ret;
>>  
>>  	if (!qcom_tzmem_using_shm_bridge)
>>  		return 0;
>>  
>> -	pfn_and_ns_perm = (u64)area->paddr | QCOM_SCM_PERM_RW;
>> -	ipfn_and_s_perm = (u64)area->paddr | QCOM_SCM_PERM_RW;
>> -	size_and_flags = area->size | (1 << QCOM_SHM_BRIDGE_NUM_VM_SHIFT);
>> +	pfn_and_ns_perm = paddr | QCOM_SCM_PERM_RW;
>> +	ipfn_and_s_perm = paddr | QCOM_SCM_PERM_RW;
>> +	size_and_flags = size | (1 << QCOM_SHM_BRIDGE_NUM_VM_SHIFT);
>> +	if (qcom_scm_shm_bridge_create(pfn_and_ns_perm, ipfn_and_s_perm,
>> +				       size_and_flags, QCOM_SCM_VMID_HLOS,
>> +				       handle))
> 
> Can we add a debug log here to ease debugging in future?
> Something like this can also work.
> 
> pr_err("Shm bridge creation failed, ret: %d, NS PA|Perm: 0x%llx,
> size|flags: 0x%llx\n", ret, pfn_and_ns_perm_flags, size_and_flags);
> 

Sure.

Regards,
Amir

>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(qcom_tzmem_shm_bridge_create);
>