Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy()

So such a synthetic CPUID bit would definitely be useful. Also, knowing whether a memcpy function is recoverable or not, should not be delegated to callers: there should be the regular memcpy APIs, plus new APIs that do everything they can to provide recoverable memory copies. Whether it's achieved via flag checking, a function pointer or code patching is an implementation detail that's not visible to drivers making use of the new facility. I'd go for the simplest, most robust solution initially, also perhaps with boot time messages to make sure users know which variant is used and now.