>-----Original Message-----
>From: De Marchi, Lucas
>Sent: Friday, June 14, 2019 2:37 PM
>To: Srivatsa, Anusha <anusha.srivatsa@xxxxxxxxx>
>Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Vivi, Rodrigo <rodrigo.vivi@xxxxxxxxx>
>Subject: Re: [PATCH 9/9] drm/i915/dmc: protect against loading wrong firmware
>
>On Fri, Jun 14, 2019 at 12:44:50PM -0700, Anusha Srivatsa wrote:
>>
>>
>>>-----Original Message-----
>>>From: De Marchi, Lucas
>>>Sent: Friday, June 7, 2019 2:13 AM
>>>To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
>>>Cc: Vivi, Rodrigo <rodrigo.vivi@xxxxxxxxx>; Srivatsa, Anusha
>>><anusha.srivatsa@xxxxxxxxx>; De Marchi, Lucas
>>><lucas.demarchi@xxxxxxxxx>
>>>Subject: [PATCH 9/9] drm/i915/dmc: protect against loading wrong
>>>firmware
>>>
>>>In intel_package_header version 2 there's a new field in the fw_info
>>>table that must be 0, otherwise it's not the correct DMC firmware. Add
>>>a check for version 2 or later.
>>>
>>>Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
>>>---
>>> drivers/gpu/drm/i915/intel_csr.c | 14 +++++++++++---
>>> 1 file changed, 11 insertions(+), 3 deletions(-)
>>>
>>>diff --git a/drivers/gpu/drm/i915/intel_csr.c
>>>b/drivers/gpu/drm/i915/intel_csr.c
>>>index 7608e4e2950d..864531aae1a5 100644
>>>--- a/drivers/gpu/drm/i915/intel_csr.c
>>>+++ b/drivers/gpu/drm/i915/intel_csr.c
>>>@@ -120,7 +120,10 @@ struct intel_css_header { } __packed;
>>>
>>> struct intel_fw_info {
>>>- u16 reserved1;
>>>+ u8 reserved1;
>>>+
>>>+ /* reserved on package_header version 1, must be 0 on version 2 */
>>>+ u8 dmc_id;
>>>
>>> /* Stepping (A, B, C, ..., *). * is a wildcard */
>>> char stepping;
>>>@@ -325,12 +328,16 @@ void intel_csr_load_program(struct
>>>drm_i915_private
>>>*dev_priv)
>>> */
>>> static u32 find_dmc_fw_offset(const struct intel_fw_info *fw_info,
>>> unsigned int num_entries,
>>>- const struct stepping_info *si)
>>>+ const struct stepping_info *si,
>>>+ u8 package_ver)
>>> {
>>> u32 dmc_offset = CSR_DEFAULT_FW_OFFSET;
>>> unsigned int i;
>>>
>>> for (i = 0; i < num_entries; i++) {
>>>+ if (package_ver > 1 && fw_info[i].dmc_id != 0)
>>>+ continue;
>>
>>Wont we need a message here? "Wrong DMC version, not loading v_x.0x" or
>something?.."
>
>I don't think so. It's normal to have other blobs inside the firmware that we don't
>care about. At most I could put a debug, but I don't think we really care.
>
>As long as we find one we should be fine. And if we don't, then we will complain
>loudly later in this function with a DRM_ERROR().
>dmc_offset remaining as CSR_DEFAULT_FW_OFFSET has a double meaning here:
>either we didn't find any entry or we found one that had the offset set to this
>value.
Ok. Makes sense.
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@xxxxxxxxx>
>Lucas De Marchi
>
>>
>>Anusha
>>> if (fw_info[i].substepping == '*' &&
>>> si->stepping == fw_info[i].stepping) {
>>> dmc_offset = fw_info[i].offset;
>>>@@ -508,7 +515,8 @@ parse_csr_fw_package(struct intel_csr *csr,
>>>
>>> fw_info = (const struct intel_fw_info *)
>>> ((u8 *)package_header + sizeof(*package_header));
>>>- dmc_offset = find_dmc_fw_offset(fw_info, num_entries, si);
>>>+ dmc_offset = find_dmc_fw_offset(fw_info, num_entries, si,
>>>+ package_header->header_ver);
>>> if (dmc_offset == CSR_DEFAULT_FW_OFFSET) {
>>> DRM_ERROR("DMC firmware not supported for %c stepping\n",
>>> si->stepping);
>>>--
>>>2.21.0
>>
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