[PATCH 17/19] mm/x86: Support large pfn mappings

Peter Xu
2024-08-09T16:09:55Z

Helpers to install and detect special pmd/pud entries. In short, bit 9 on
x86 is not used for pmd/pud, so we can directly define them the same as the
pte level. One note is that it's also used in _PAGE_BIT_CPA_TEST but that
is only used in the debug test, and shouldn't conflict in this case.

One note is that pxx_set|clear_flags() for pmd/pud will need to be moved
upper so that they can be referenced by the new special bit helpers.
There's no change in the code that was moved.

Cc: x86@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/pgtable.h | 80 ++++++++++++++++++++++------------
2 files changed, 53 insertions(+), 28 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index acd9745bf2ae..7a3fb2ff3e72 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -28,6 +28,7 @@ config X86_64
select ARCH_HAS_GIGANTIC_PAGE
select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
select ARCH_SUPPORTS_PER_VMA_LOCK
+ select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
select HAVE_ARCH_SOFT_DIRTY
select MODULES_USE_ELF_RELA
select NEED_DMA_MAP_STATE
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index a7c1e9cfea41..1e463c9a650f 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -120,6 +120,34 @@ extern pmdval_t early_pmd_flags;
#define arch_end_context_switch(prev) do {} while(0)
#endif /* CONFIG_PARAVIRT_XXL */

+static inline pmd_t pmd_set_flags(pmd_t pmd, pmdval_t set)
+{
+ pmdval_t v = native_pmd_val(pmd);
+
+ return native_make_pmd(v | set);
+}
+
+static inline pmd_t pmd_clear_flags(pmd_t pmd, pmdval_t clear)
+{
+ pmdval_t v = native_pmd_val(pmd);
+
+ return native_make_pmd(v & ~clear);
+}
+
+static inline pud_t pud_set_flags(pud_t pud, pudval_t set)
+{
+ pudval_t v = native_pud_val(pud);
+
+ return native_make_pud(v | set);
+}
+
+static inline pud_t pud_clear_flags(pud_t pud, pudval_t clear)
+{
+ pudval_t v = native_pud_val(pud);
+
+ return native_make_pud(v & ~clear);
+}
+
/*
* The following only work if pte_present() is true.
* Undefined behaviour if not..
@@ -317,6 +345,30 @@ static inline int pud_devmap(pud_t pud)
}
#endif

+#ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
+static inline bool pmd_special(pmd_t pmd)
+{
+ return pmd_flags(pmd) & _PAGE_SPECIAL;
+}
+
+static inline pmd_t pmd_mkspecial(pmd_t pmd)
+{
+ return pmd_set_flags(pmd, _PAGE_SPECIAL);
+}
+#endif /* CONFIG_ARCH_SUPPORTS_PMD_PFNMAP */
+
+#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
+static inline bool pud_special(pud_t pud)
+{
+ return pud_flags(pud) & _PAGE_SPECIAL;
+}
+
+static inline pud_t pud_mkspecial(pud_t pud)
+{
+ return pud_set_flags(pud, _PAGE_SPECIAL);
+}
+#endif /* CONFIG_ARCH_SUPPORTS_PUD_PFNMAP */
+
static inline int pgd_devmap(pgd_t pgd)
{
return 0;
@@ -487,20 +539,6 @@ static inline pte_t pte_mkdevmap(pte_t pte)
return pte_set_flags(pte, _PAGE_SPECIAL|_PAGE_DEVMAP);
}

-static inline pmd_t pmd_set_flags(pmd_t pmd, pmdval_t set)
-{
- pmdval_t v = native_pmd_val(pmd);
-
- return native_make_pmd(v | set);
-}
-
-static inline pmd_t pmd_clear_flags(pmd_t pmd, pmdval_t clear)
-{
- pmdval_t v = native_pmd_val(pmd);
-
- return native_make_pmd(v & ~clear);
-}
-
/* See comments above mksaveddirty_shift() */
static inline pmd_t pmd_mksaveddirty(pmd_t pmd)
{
@@ -595,20 +633,6 @@ static inline pmd_t pmd_mkwrite_novma(pmd_t pmd)
pmd_t pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma);
#define pmd_mkwrite pmd_mkwrite

-static inline pud_t pud_set_flags(pud_t pud, pudval_t set)
-{
- pudval_t v = native_pud_val(pud);
-
- return native_make_pud(v | set);
-}
-
-static inline pud_t pud_clear_flags(pud_t pud, pudval_t clear)
-{
- pudval_t v = native_pud_val(pud);
-
- return native_make_pud(v & ~clear);
-}
-
/* See comments above mksaveddirty_shift() */
static inline pud_t pud_mksaveddirty(pud_t pud)
{
--
2.45.0