Re: [Intel-gfx] [PATCH 5/5] drm/i915/uc: Reject doplicate entries in firmware table

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On 4/19/2023 10:12 AM, John Harrison wrote:
On 4/19/2023 10:02, John Harrison wrote:
On 4/18/2023 16:24, Ceraolo Spurio, Daniele wrote:
Typo doplicate in patch title

On 4/14/2023 5:57 PM, John.C.Harrison@xxxxxxxxx wrote:
From: John Harrison <John.C.Harrison@xxxxxxxxx>

It was noticed that duplicte entries in the firmware table could cause

typo duplicte

an infinite loop in the firmware loading code if that entry failed to
load. Duplicate entries are a bug anyway and so should never happen.
Ensure they don't by tweaking the table validation code to reject
duplicates.

Here you're not really rejecting anything though, just printing an error (and even that only if the SELFTEST kconfig is selected). This would allow our CI to catch issues with patches sent to our ML, but IIRC the reported bug was on a kernel fork. We could disable the FW loading is the table for that particular blob type is in an invalid state, as it wouldn't be safe to attempt a load in that case anyway.
The validation code is rejecting duplicates. Whether the driver loads or not after a failed validation is another matter.

I was basically assuming that CI will fail on the error message and thus prevent such code ever being merged. But yeah, I guess we don't run CI on backports to stable kernels and such. Although, I would hope that anyone pushing patches to a stable kernel would run some testing on it first!

Any thoughts on a good way to fail the load? We don't want to just pretend that firmware is not wanted/required on the platform and just load the i915 module without the firmware. Also, what about the longer plan of moving the validation to a selftest. You can't fail the load at all then.
Actually, forgot we already have a INTEL_UC_FIRMWARE_ERROR status. That works fine for aborting the load. So just go with that and drop the plan to move to a selftest?

John.

I do actually like the idea of moving this code to a mock selftest. Maybe just add a comment above the tables making clear that duplicated entries are not allowed and will break the loading flow?

Daniele




John.



For full m/m/p files, that can be done by simply tweaking the patch
level check to reject matching values. For reduced version entries,
the filename itself must be compared.

Signed-off-by: John Harrison <John.C.Harrison@xxxxxxxxx>
---
  drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 27 +++++++++++++++++++++---
  1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
index c589782467265..44829247ef6bc 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
@@ -319,7 +319,7 @@ static void validate_fw_table_type(struct drm_i915_private *i915, enum intel_uc_
  {
      const struct uc_fw_platform_requirement *fw_blobs;
      u32 fw_count;
-    int i;
+    int i, j;
        if (type >= ARRAY_SIZE(blobs_all)) {
          drm_err(&i915->drm, "No blob array for %s\n", intel_uc_fw_type_repr(type)); @@ -334,6 +334,27 @@ static void validate_fw_table_type(struct drm_i915_private *i915, enum intel_uc_
        /* make sure the list is ordered as expected */
      for (i = 1; i < fw_count; i++) {
+        /* Versionless file names must be unique per platform: */
+        for (j = i + 1; j < fw_count; j++) {
+            /* Same platform? */
+            if (fw_blobs[i].p != fw_blobs[j].p)
+                continue;
+
+            if (fw_blobs[i].blob.path != fw_blobs[j].blob.path)
+                continue;
+
+            drm_err(&i915->drm, "Diplicaate %s blobs: %s r%u %s%d.%d.%d [%s] matches %s r%u %s%d.%d.%d [%s]\n",

Typo Diplicaate

Daniele

+ intel_uc_fw_type_repr(type),
+                intel_platform_name(fw_blobs[j].p), fw_blobs[j].rev,
+                fw_blobs[j].blob.legacy ? "L" : "v",
+                fw_blobs[j].blob.major, fw_blobs[j].blob.minor,
+                fw_blobs[j].blob.patch, fw_blobs[j].blob.path,
+                intel_platform_name(fw_blobs[i].p), fw_blobs[i].rev,
+                fw_blobs[i].blob.legacy ? "L" : "v",
+                fw_blobs[i].blob.major, fw_blobs[i].blob.minor,
+                fw_blobs[i].blob.patch, fw_blobs[i].blob.path);
+        }
+
          /* Next platform is good: */
          if (fw_blobs[i].p < fw_blobs[i - 1].p)
              continue;
@@ -377,8 +398,8 @@ static void validate_fw_table_type(struct drm_i915_private *i915, enum intel_uc_
          if (fw_blobs[i].blob.minor != fw_blobs[i - 1].blob.minor)
              goto bad;
  -        /* Patch versions must be in order: */
-        if (fw_blobs[i].blob.patch <= fw_blobs[i - 1].blob.patch)
+        /* Patch versions must be in order and unique: */
+        if (fw_blobs[i].blob.patch < fw_blobs[i - 1].blob.patch)
              continue;
    bad:







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