On Tue, Jun 26, 2018 at 05:22:40PM +0300, Kirill A. Shutemov wrote:
> The new helper mktme_disable() allows to disable MKTME even if it's
> enumerated successfully. MKTME initialization may fail and this
> functionality allows system to boot regardless of the failure.
>
> MKTME needs per-KeyID direct mapping. It requires a lot more virtual
> address space which may be a problem in 4-level paging mode. If the
> system has more physical memory than we can handle with MKTME.
.. then what should happen?
> The feature allows to fail MKTME, but boot the system successfully.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
> arch/x86/include/asm/mktme.h | 2 ++
> arch/x86/kernel/cpu/intel.c | 5 +----
> arch/x86/mm/mktme.c | 9 +++++++++
> 3 files changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/include/asm/mktme.h b/arch/x86/include/asm/mktme.h
> index 44409b8bbaca..ebbee6a0c495 100644
> --- a/arch/x86/include/asm/mktme.h
> +++ b/arch/x86/include/asm/mktme.h
> @@ -6,6 +6,8 @@
>
> struct vm_area_struct;
>
> +void mktme_disable(void);
> +
> #ifdef CONFIG_X86_INTEL_MKTME
> extern phys_addr_t mktme_keyid_mask;
> extern int mktme_nr_keyids;
> diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
> index efc9e9fc47d4..75e3b2602b4a 100644
> --- a/arch/x86/kernel/cpu/intel.c
> +++ b/arch/x86/kernel/cpu/intel.c
> @@ -591,10 +591,7 @@ static void detect_tme(struct cpuinfo_x86 *c)
> * Maybe needed if there's inconsistent configuation
> * between CPUs.
> */
> - physical_mask = (1ULL << __PHYSICAL_MASK_SHIFT) - 1;
> - mktme_keyid_mask = 0;
> - mktme_keyid_shift = 0;
> - mktme_nr_keyids = 0;
> + mktme_disable();
> }
> #endif
>
> diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c
> index 1194496633ce..bb6210dbcf0e 100644
> --- a/arch/x86/mm/mktme.c
> +++ b/arch/x86/mm/mktme.c
> @@ -13,6 +13,15 @@ static inline bool mktme_enabled(void)
> return static_branch_unlikely(&mktme_enabled_key);
> }
>
> +void mktme_disable(void)
> +{
> + physical_mask = (1ULL << __PHYSICAL_MASK_SHIFT) - 1;
> + mktme_keyid_mask = 0;
> + mktme_keyid_shift = 0;
> + mktme_nr_keyids = 0;
> + static_branch_disable(&mktme_enabled_key);
> +}
> +
> int page_keyid(const struct page *page)
> {
> if (!mktme_enabled())
> --
> 2.18.0
>
