Re: [PATCH v6 05/45] drm/amd: Add a new helper for loading/validating microcode

[Mario Limonciello]

On 1/4/23 23:29, Lazar, Lijo wrote:
> On 1/5/2023 10:53 AM, Mario Limonciello wrote:
> > On 1/4/23 23:07, Lazar, Lijo wrote:
> > > On 1/5/2023 9:12 AM, Mario Limonciello wrote:
> > > > All microcode runs a basic validation after it's been loaded. Each
> > > > IP block as part of init will run both.
> > > >
> > > > Introduce a wrapper for request_firmware and amdgpu_ucode_validate.
> > > > This wrapper will also remap any error codes from request_firmware
> > > > to -ENODEV.  This is so that early_init will fail if firmware couldn't
> > > > be loaded instead of the IP block being disabled.
> > > >
> > > > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> > > > ---
> > > > v5->v6:
> > > >   * Fix argument to be ** not *
> > > > ---
> > > >   drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.c | 36 
> > > > +++++++++++++++++++++++
> > > >   drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.h |  3 ++
> > > >   2 files changed, 39 insertions(+)
> > > >
> > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.c 
> > > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.c
> > > > index eafcddce58d3..8ebfec12da87 100644
> > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.c
> > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.c
> > > > @@ -1312,3 +1312,39 @@ void amdgpu_ucode_ip_version_decode(struct 
> > > > amdgpu_device *adev, int block_type,
> > > >       snprintf(ucode_prefix, len, "%s_%d_%d_%d", ip_name, maj, min, 
> > > > rev);
> > > >   }
> > > > +
> > > > +/*
> > > > + * amdgpu_ucode_request - Fetch and validate amdgpu microcode
> > > > + *
> > > > + * @adev: amdgpu device
> > > > + * @fw: pointer to load firmware to
> > > > + * @fw_name: firmware to load
> > > > + *
> > > > + * This is a helper that will use request_firmware and 
> > > > amdgpu_ucode_validate
> > > > + * to load and run basic validation on firmware. If the load fails, 
> > > > remap
> > > > + * the error code to -ENODEV, so that early_init functions will 
> > > > fail to load.
> > > > + */
> > > > +int amdgpu_ucode_request(struct amdgpu_device *adev, const struct 
> > > > firmware **fw,
> > > > +             const char *fw_name)
> > > > +{
> > > > +    int err = request_firmware(fw, fw_name, adev->dev);
> > > > +
> > > > +    if (err)
> > > > +        return -ENODEV;
> > > > +    err = amdgpu_ucode_validate(*fw);
> > > > +    if (err)
> > > > +        dev_dbg(adev->dev, "\"%s\" failed to validate\n", fw_name);
> > > > +
> > >
> > > Missed this earlier. If validate fails, shouldn't this undo the 
> > > request operation by calling release?
> >
> > Actually that was original design, but there is one place in the 
> > codebase that expects that ucode validation can fail, and so leave the 
> > evaluate of error code and cleanup outside of helper.
>
> I see. Does request_firmware assure that fw pointer be always NULL if it 
> fails? Or should that be done here if request_ fails? In subsequent 
> patches, I see clients calling release without checking what caused the 
> failure.

Yes, according to docs 
(https://docs.kernel.org/next/driver-api/firmware/request_firmware.html#request-firmware-api-expected-driver-use)

> Thanks,
> Lijo
>
> > > Thanks,
> > > Lijo
> > >
> > > > +    return err;
> > > > +}
> > > > +
> > > > +/*
> > > > + * amdgpu_ucode_release - Release firmware microcode
> > > > + *
> > > > + * @fw: pointer to firmware to release
> > > > + */
> > > > +void amdgpu_ucode_release(const struct firmware **fw)
> > > > +{
> > > > +    release_firmware(*fw);
> > > > +    *fw = NULL;
> > > > +}
> > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.h 
> > > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.h
> > > > index 552e06929229..848579d4988b 100644
> > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.h
> > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ucode.h
> > > > @@ -544,6 +544,9 @@ void amdgpu_ucode_print_sdma_hdr(const struct 
> > > > common_firmware_header *hdr);
> > > >   void amdgpu_ucode_print_psp_hdr(const struct 
> > > > common_firmware_header *hdr);
> > > >   void amdgpu_ucode_print_gpu_info_hdr(const struct 
> > > > common_firmware_header *hdr);
> > > >   int amdgpu_ucode_validate(const struct firmware *fw);
> > > > +int amdgpu_ucode_request(struct amdgpu_device *adev, const struct 
> > > > firmware **fw,
> > > > +             const char *fw_name);
> > > > +void amdgpu_ucode_release(const struct firmware **fw);
> > > >   bool amdgpu_ucode_hdr_version(union amdgpu_firmware_header *hdr,
> > > >                   uint16_t hdr_major, uint16_t hdr_minor);