[PATCH v2 5/7] x86, mm: Support huge KVA mappings on x86

[Toshi Kani <toshi.kani@hp.com>]

Implement huge KVA mapping interfaces on x86.  Select
HAVE_ARCH_HUGE_VMAP when X86_64 or X86_32 with X86_PAE is set.
Without X86_PAE set, the X86_32 kernel has the 2-level page
tables and cannot provide the huge KVA mappings.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
---
 arch/x86/Kconfig      |    1 +
 arch/x86/mm/pgtable.c |   34 ++++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0dc9d01..a79e286 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -97,6 +97,7 @@ config X86
 	select IRQ_FORCED_THREADING
 	select HAVE_BPF_JIT if X86_64
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
+	select HAVE_ARCH_HUGE_VMAP if X86_64 || (X86_32 && X86_PAE)
 	select ARCH_HAS_SG_CHAIN
 	select CLKEVT_I8253
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 6fb6927..e495432 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -481,3 +481,37 @@ void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys,
 {
 	__native_set_fixmap(idx, pfn_pte(phys >> PAGE_SHIFT, flags));
 }
+
+#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
+void pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
+{
+	set_pte((pte_t *)pud, pfn_pte(
+		(u64)addr >> PAGE_SHIFT,
+		__pgprot(pgprot_val(prot) | _PAGE_PSE)));
+}
+
+void pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
+{
+	set_pte((pte_t *)pmd, pfn_pte(
+		(u64)addr >> PAGE_SHIFT,
+		__pgprot(pgprot_val(prot) | _PAGE_PSE)));
+}
+
+int pud_clear_huge(pud_t *pud)
+{
+	if (pud_large(*pud)) {
+		pud_clear(pud);
+		return 1;
+	}
+	return 0;
+}
+
+int pmd_clear_huge(pmd_t *pmd)
+{
+	if (pmd_large(*pmd)) {
+		pmd_clear(pmd);
+		return 1;
+	}
+	return 0;
+}
+#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */