x86/mm: Fix up comments around PMD preallocation
The "paravirt environment" is no longer in the tree. Axe that part of the
comment. Also add a blurb to remind readers that "USER_PMDS" refer to
the PTI user *copy* of the page tables, not the user *porttion*.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 8e5e696..941709b 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -160,16 +160,17 @@ static void pgd_dtor(pgd_t *pgd)
* processor notices the update. Since this is expensive, and
* all 4 top-level entries are used almost immediately in a
* new process's life, we just pre-populate them here.
- *
- * Also, if we're in a paravirt environment where the kernel pmd is
- * not shared between pagetables (!SHARED_KERNEL_PMDS), we allocate
- * and initialize the kernel pmds here.
*/
#define PREALLOCATED_PMDS (static_cpu_has(X86_FEATURE_PTI) ? \
PTRS_PER_PGD : KERNEL_PGD_BOUNDARY)
#define MAX_PREALLOCATED_PMDS PTRS_PER_PGD
/*
+ * "USER_PMDS" are the PMDs for the user copy of the page tables when
+ * PTI is enabled. They do not exist when PTI is disabled. Note that
+ * this is distinct from the user _portion_ of the kernel page tables
+ * which always exists.
+ *
* We allocate separate PMDs for the kernel part of the user page-table
* when PTI is enabled. We need them to map the per-process LDT into the
* user-space page-table.
