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Subject[PATCHv5 14/19] x86/mm: Allow to disable MKTME after enumeration
Date
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 the
feature allows to fail MKTME, but boot the system successfully.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
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
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