On 11/21/2022 11:38 PM, Borislav Petkov wrote: > On Mon, Nov 21, 2022 at 10:46:21PM +0800, Jiaxi Chen wrote: >> Features which has been enabled in kernel usually should be added to >> /proc/cpuinfo. > > No, pls read this first: Documentation/x86/cpuinfo.rst > > If something's not clear, we will extend it so that it is. > > /proc/cpuinfo - a user ABI - is not a dumping ground for CPUID bits. > Thanks. Sorry for the miss understanding. For those feature bits who have truly kernel usage, their flags should appear in /proc/cpuinfo. For others, they are not generally show up here, it depends. As for features in this patch series: The first-way defined bits are on an expected-dense cpuid leaf[1] and some of their siblings have kernel usages[2]. Given that, define them like X86_FEATURE_* in arch/x86/include/asm/cpufeatures.h. But due to their complicated and unreadable feature name[3], prefer to hide them in /proc/cpuinfo. The second-way defined bits are on a new and sparse cpuid leaf. Besides, these bits have no turly kernel use case. Therefore, move these new bits to kvm-only leaves to achieve the purpose for advertising these bits to kvm userspace[4]. Then of course they will not show up in /proc/cpuinfo. [1] https://lore.kernel.org/all/Y3O7UYWfOLfJkwM%2F@xxxxxxx/ [2] https://lore.kernel.org/all/f8607d23-afaa-2670-dd03-2ae8ec1e79a0@xxxxxxxxx/ [3] https://lore.kernel.org/all/6d7fae50-ef3c-dc1e-336c-691095007117@xxxxxxxxx/ [4] https://lore.kernel.org/all/Y1ATKF2xjERFbspn@xxxxxxxxxx/ -- Regards, Jiaxi
