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authorJeremy Compostella <jeremy.compostella@intel.com>2024-08-16 13:20:26 -0700
committerJérémy Compostella <jeremy.compostella@intel.com>2024-08-21 15:54:58 +0000
commit58dc892bbeb28a9cb14796f3bf6af779ae4fbe89 (patch)
treebc9921a327710e0b4b1fa362aaf9046918370f70 /util/ectool/description.md
parent1dd8991fef5e4c5174cdcdd1e1e44c5d1fa9ed0e (diff)
soc/intel/common/block/cpu: Fix ways count computation regression
Commit 16ab9bdcd578612bb3822373547f939eb90afd82 ("soc/intel/common: Calculate and configure SF Mask 2") breaks the computation of the number of ways and as result, all the derived masks. It results in MSR such as `IA32_L3_MASK_1' to be improperly programmed yielding unpredictable NEM issues such as hangs. Indeed, this commit has introduced a backup of 0x1 into %edx before comparing the requested cache-as-RAM size against the way size. When the requested cache-as-RAM is larger, it reaches the second part of the algorithm which computes the necessary number of ways to fit the requested cache-as-RAM. This algorithm uses the `div' instruction. Per specification, the div instruction divides the 64 bits combination of %edx and %eax register. Since 0x1 got backed up in %edx and assuming a `CONFIG_DCACHE_RAM_SIZE' of 0x200000, we end up dividing 0x100200000 by the way size instead of 0x200000 which result in a necessary number of ways of 4098 for a way size of 0x100000. This commit clears the %edx register before calling the `div' instruction. BUG=b:360332771 TEST=Verified on PTL Intel reference platform Change-Id: I5cb66da0aa977eecb64a0021268a6827747c521d Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/83948 Reviewed-by: Wonkyu Kim <wonkyu.kim@intel.com> Reviewed-by: Subrata Banik <subratabanik@google.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
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