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Date:   Wed, 11 Oct 2023 08:55:49 -0500
From:   Andrew Halaney <ahalaney@redhat.com>
To:     Bartosz Golaszewski <brgl@bgdev.pl>
Cc:     Andy Gross <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Elliot Berman <quic_eberman@quicinc.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Guru Das Srinagesh <quic_gurus@quicinc.com>,
        Maximilian Luz <luzmaximilian@gmail.com>,
        Alex Elder <elder@linaro.org>,
        Srini Kandagatla <srinivas.kandagatla@linaro.org>,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, kernel@quicinc.com,
        Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Subject: Re: [PATCH v3 11/15] firmware: qcom: qseecom: convert to using the
 TZ allocator
Message-ID: <ebihxhbl2hyhuke3l2nm56yhvmj4qcja6fbihrc4bhrf2czoix@wjnnyic7wvi7>
References: <20231009153427.20951-1-brgl@bgdev.pl>
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On Wed, Oct 11, 2023 at 09:44:54AM +0200, Bartosz Golaszewski wrote:
> On Wed, Oct 11, 2023 at 12:49 AM Andrew Halaney <ahalaney@redhat.com> wrote:
> >
> > On Mon, Oct 09, 2023 at 05:34:23PM +0200, Bartosz Golaszewski wrote:
> > > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> > >
> > > Drop the DMA mapping operations from qcom_scm_qseecom_app_send() and
> > > convert all users of it in the qseecom module to using the TZ allocator
> > > for creating SCM call buffers. Together with using the cleanup macros,
> > > it has the added benefit of a significant code shrink. As this is
> > > largely a module separate from the SCM driver, let's use a separate
> > > memory pool.
> > >
> > > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> >
> > <snip>
> >
> > > @@ -567,20 +529,14 @@ static efi_status_t qsee_uefi_get_next_variable(struct qcuefi_client *qcuefi,
> > >               return EFI_INVALID_PARAMETER;
> > >
> > >       status = qcom_qseecom_app_send(qcuefi->client, req_data, req_size, rsp_data, rsp_size);
> > > -     if (status) {
> > > -             efi_status = EFI_DEVICE_ERROR;
> > > -             goto out_free;
> > > -     }
> > > +     if (status)
> > > +             return EFI_DEVICE_ERROR;
> > >
> > > -     if (rsp_data->command_id != QSEE_CMD_UEFI_GET_NEXT_VARIABLE) {
> > > -             efi_status = EFI_DEVICE_ERROR;
> > > -             goto out_free;
> > > -     }
> > > +     if (rsp_data->command_id != QSEE_CMD_UEFI_GET_NEXT_VARIABLE)
> > > +             return EFI_DEVICE_ERROR;
> > >
> > > -     if (rsp_data->length < sizeof(*rsp_data)) {
> > > -             efi_status = EFI_DEVICE_ERROR;
> > > -             goto out_free;
> > > -     }
> > > +     if (rsp_data->length < sizeof(*rsp_data))
> > > +             return EFI_DEVICE_ERROR;
> > >
> > >       if (rsp_data->status) {
> > >               dev_dbg(qcuefi_dev(qcuefi), "%s: uefisecapp error: 0x%x\n",
> > > @@ -595,77 +551,59 @@ static efi_status_t qsee_uefi_get_next_variable(struct qcuefi_client *qcuefi,
> > >               if (efi_status == EFI_BUFFER_TOO_SMALL)
> > >                       *name_size = rsp_data->name_size;
> > >
> > > -             goto out_free;
> > > +             return efi_status;
> > >       }
> > >
> > > -     if (rsp_data->length > rsp_size) {
> > > -             efi_status = EFI_DEVICE_ERROR;
> > > -             goto out_free;
> > > -     }
> > > +     if (rsp_data->length > rsp_size)
> > > +             return EFI_DEVICE_ERROR;
> > >
> > > -     if (rsp_data->name_offset + rsp_data->name_size > rsp_data->length) {
> > > -             efi_status = EFI_DEVICE_ERROR;
> > > -             goto out_free;
> > > -     }
> > > +     if (rsp_data->name_offset + rsp_data->name_size > rsp_data->length)
> > > +             return EFI_DEVICE_ERROR;
> > >
> > > -     if (rsp_data->guid_offset + rsp_data->guid_size > rsp_data->length) {
> > > -             efi_status = EFI_DEVICE_ERROR;
> > > -             goto out_free;
> > > -     }
> > > +     if (rsp_data->guid_offset + rsp_data->guid_size > rsp_data->length)
> > > +             return EFI_DEVICE_ERROR;
> > >
> > >       if (rsp_data->name_size > *name_size) {
> > >               *name_size = rsp_data->name_size;
> > > -             efi_status = EFI_BUFFER_TOO_SMALL;
> > > -             goto out_free;
> > > +             return EFI_BUFFER_TOO_SMALL;
> > >       }
> > >
> > > -     if (rsp_data->guid_size != sizeof(*guid)) {
> > > -             efi_status = EFI_DEVICE_ERROR;
> > > -             goto out_free;
> > > -     }
> > > +     if (rsp_data->guid_size != sizeof(*guid))
> > > +             return EFI_DEVICE_ERROR;
> > >
> > >       memcpy(guid, ((void *)rsp_data) + rsp_data->guid_offset, rsp_data->guid_size);
> > >       status = ucs2_strscpy(name, ((void *)rsp_data) + rsp_data->name_offset,
> > >                             rsp_data->name_size / sizeof(*name));
> > >       *name_size = rsp_data->name_size;
> > >
> > > -     if (status < 0) {
> > > +     if (status < 0)
> > >               /*
> > >                * Return EFI_DEVICE_ERROR here because the buffer size should
> > >                * have already been validated above, causing this function to
> > >                * bail with EFI_BUFFER_TOO_SMALL.
> > >                */
> > >               return EFI_DEVICE_ERROR;
> > > -     }
> >
> > Personally (no idea what the actual style guide says) leaving braces
> > around the multiline if statement would be nice.... that being said,
> > that's my opinion :)
> >
> > <snip>
> > > @@ -704,12 +635,7 @@ static efi_status_t qsee_uefi_query_variable_info(struct qcuefi_client *qcuefi,
> > >       if (max_variable_size)
> > >               *max_variable_size = rsp_data->max_variable_size;
> > >
> > > -out_free:
> > > -     kfree(rsp_data);
> > > -out_free_req:
> > > -     kfree(req_data);
> > > -out:
> > > -     return efi_status;
> > > +     return EFI_SUCCESS;
> > >  }
> > >
> > >  /* -- Global efivar interface. ---------------------------------------------- */
> > > @@ -838,6 +764,10 @@ static int qcom_uefisecapp_probe(struct auxiliary_device *aux_dev,
> > >       if (status)
> > >               qcuefi_set_reference(NULL);
> > >
> > > +     qcuefi->mempool = devm_qcom_tzmem_pool_new(&aux_dev->dev, SZ_256K);
> >
> > Any particular reason for this size? Just curious, it was (one) of the
> > reasons I had not marked patch 4 yet (it looks good, but I wanted to get
> > through the series to digest the Kconfig as well).
> >
> 
> I cannot test this. Do you know what the minimum correct size would be?

I've got no insight into these firmware interfaces unfortunately. Was
mostly curious if Qualcomm had provided a suggestion behind the scenes
or if this was picked as a "sufficiently large" pool size.

> 
> Bart
> 
> > Reviewed-by: Andrew Halaney <ahalaney@redhat.com>
> >
>