From: Pierre Gondois <pierre.gondois@xxxxxxx>
[ Upstream commit 7a306e3eabf2b2fd8cffa69b87b32dbf814d79ce ]
If there is no ACPI/DT information, it is assumed that L1 caches
are private and L2 (and higher) caches are shared. A cache is
'shared' between two CPUs if it is accessible from these two
CPUs.
Each CPU owns a representation (i.e. has a dedicated cacheinfo struct)
of the caches it has access to. cache_leaves_are_shared() tries to
identify whether two representations are designating the same actual
cache.
In cache_leaves_are_shared(), if 'this_leaf' is a L2 cache (or higher)
and 'sib_leaf' is a L1 cache, the caches are detected as shared as
only this_leaf's cache level is checked.
This is leads to setting sib_leaf as being shared with another CPU,
which is incorrect as this is a L1 cache.
Check 'sib_leaf->level'. Also update the comment as the function is
called when populating 'shared_cpu_map'.
Fixes: f16d1becf96f ("cacheinfo: Use cache identifiers to check if the caches are shared if available")
Signed-off-by: Pierre Gondois <pierre.gondois@xxxxxxx>
Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230414081453.244787-2-pierre.gondois@xxxxxxx
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/base/cacheinfo.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index f05acf3c16c6b..88205a240fb2e 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -38,11 +38,10 @@ static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf,
{
/*
* For non DT/ACPI systems, assume unique level 1 caches,
- * system-wide shared caches for all other levels. This will be used
- * only if arch specific code has not populated shared_cpu_map
+ * system-wide shared caches for all other levels.
*/
if (!(IS_ENABLED(CONFIG_OF) || IS_ENABLED(CONFIG_ACPI)))
- return !(this_leaf->level == 1);
+ return (this_leaf->level != 1) && (sib_leaf->level != 1);
if ((sib_leaf->attributes & CACHE_ID) &&
(this_leaf->attributes & CACHE_ID))
--
2.39.2
