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Subject[RFC PATCH 10/13] x86/mm: Add NR page bit for KVM XO
Date
Add _PAGE_BIT_NR and _PAGE_NR, the values of which are determined
dynamically at boot. This page type is only valid after checking for for
the KVM XO CPUID bit.

Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
arch/x86/include/asm/pgtable_types.h | 11 +++++++++++
arch/x86/mm/init.c | 3 +++
2 files changed, 14 insertions(+)

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index b5e49e6bac63..d3c92c992089 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -30,6 +30,14 @@
#define _PAGE_BIT_PKEY_BIT3 62 /* Protection Keys, bit 4/4 */
#define _PAGE_BIT_NX 63 /* No execute: only valid after cpuid check */

+#if defined(CONFIG_KVM_XO) && !defined(__ASSEMBLY__)
+extern unsigned int __pgtable_kvmxo_bit;
+/* KVM based not-readable: only valid after cpuid check */
+#define _PAGE_BIT_NR (__pgtable_kvmxo_bit)
+#else /* defined(CONFIG_KVM_XO) && !defined(__ASSEMBLY__) */
+#define _PAGE_BIT_NR 0
+#endif /* defined(CONFIG_KVM_XO) && !defined(__ASSEMBLY__) */
+
#define _PAGE_BIT_SPECIAL _PAGE_BIT_SOFTW1
#define _PAGE_BIT_CPA_TEST _PAGE_BIT_SOFTW1
#define _PAGE_BIT_SOFT_DIRTY _PAGE_BIT_SOFTW3 /* software dirty tracking */
@@ -39,6 +47,9 @@
/* - if the user mapped it with PROT_NONE; pte_present gives true */
#define _PAGE_BIT_PROTNONE _PAGE_BIT_GLOBAL

+#define _PAGE_NR (pgtable_kvmxo_enabled() ? \
+ (_AT(pteval_t, 1) << _PAGE_BIT_NR) : 0)
+
#define _PAGE_PRESENT (_AT(pteval_t, 1) << _PAGE_BIT_PRESENT)
#define _PAGE_RW (_AT(pteval_t, 1) << _PAGE_BIT_RW)
#define _PAGE_USER (_AT(pteval_t, 1) << _PAGE_BIT_USER)
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index fd10d91a6115..7298156a76d5 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -195,6 +195,9 @@ static void __init probe_page_size_mask(void)
__supported_pte_mask |= _PAGE_GLOBAL;
}

+ if (pgtable_kvmxo_enabled())
+ __supported_pte_mask |= _PAGE_NR;
+
/* By the default is everything supported: */
__default_kernel_pte_mask = __supported_pte_mask;
/* Except when with PTI where the kernel is mostly non-Global: */
--
2.17.1
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