[patch V2 2/5] x86/kaiser: Simplify disabling of global pages

[Thomas Gleixner <tglx@linutronix.de>]

[-- Attachment #1: x86-kaiser--Make-page-global-disabling-sane.patch --]
[-- Type: text/plain, Size: 3990 bytes --]

The current way of disabling global pages at compile time prevents boot
time disabling of kaiser and creates unnecessary indirections.

Global pages can be supressed by __supported_pte_mask as well. The shadow
mappings set PAGE_GLOBAL for the minimal kernel mappings which are required
for entry/exit. These mappings are setup manually so the filtering does not
take place.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/pgtable_types.h |   16 +---------------
 arch/x86/mm/init.c                   |   13 ++++++++++---
 arch/x86/mm/pageattr.c               |   16 ++++++++--------
 3 files changed, 19 insertions(+), 26 deletions(-)

--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -191,23 +191,9 @@ enum page_cache_mode {
 #define PAGE_READONLY_EXEC	__pgprot(_PAGE_PRESENT | _PAGE_USER |	\
 					 _PAGE_ACCESSED)
 
-/*
- * Disable global pages for anything using the default
- * __PAGE_KERNEL* macros.
- *
- * PGE will still be enabled and _PAGE_GLOBAL may still be used carefully
- * for a few selected kernel mappings which must be visible to userspace,
- * when KAISER is enabled, like the entry/exit code and data.
- */
-#ifdef CONFIG_KAISER
-#define __PAGE_KERNEL_GLOBAL	0
-#else
-#define __PAGE_KERNEL_GLOBAL	_PAGE_GLOBAL
-#endif
-
 #define __PAGE_KERNEL_EXEC						\
 	(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED |	\
-	 __PAGE_KERNEL_GLOBAL)
+	 _PAGE_GLOBAL)
 #define __PAGE_KERNEL		(__PAGE_KERNEL_EXEC | _PAGE_NX)
 
 #define __PAGE_KERNEL_RO		(__PAGE_KERNEL & ~_PAGE_RW)
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -161,6 +161,13 @@ struct map_range {
 
 static int page_size_mask;
 
+static void enable_global_pages(void)
+{
+#ifndef CONFIG_KAISER
+	__supported_pte_mask |= _PAGE_GLOBAL;
+#endif
+}
+
 static void __init probe_page_size_mask(void)
 {
 	/*
@@ -179,11 +186,11 @@ static void __init probe_page_size_mask(
 		cr4_set_bits_and_update_boot(X86_CR4_PSE);
 
 	/* Enable PGE if available */
+	__supported_pte_mask |= _PAGE_GLOBAL;
 	if (boot_cpu_has(X86_FEATURE_PGE)) {
 		cr4_set_bits_and_update_boot(X86_CR4_PGE);
-		__supported_pte_mask |= _PAGE_GLOBAL;
-	} else
-		__supported_pte_mask &= ~_PAGE_GLOBAL;
+		enable_global_pages();
+	}
 
 	/* Enable 1 GB linear kernel mappings if available: */
 	if (direct_gbpages && boot_cpu_has(X86_FEATURE_GBPAGES)) {
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -585,9 +585,9 @@ try_preserve_large_page(pte_t *kpte, uns
 	 * for the ancient hardware that doesn't support it.
 	 */
 	if (pgprot_val(req_prot) & _PAGE_PRESENT)
-		pgprot_val(req_prot) |= _PAGE_PSE | __PAGE_KERNEL_GLOBAL;
+		pgprot_val(req_prot) |= _PAGE_PSE | _PAGE_GLOBAL;
 	else
-		pgprot_val(req_prot) &= ~(_PAGE_PSE | __PAGE_KERNEL_GLOBAL);
+		pgprot_val(req_prot) &= ~(_PAGE_PSE | _PAGE_GLOBAL);
 
 	req_prot = canon_pgprot(req_prot);
 
@@ -705,9 +705,9 @@ static int
 	 * for the ancient hardware that doesn't support it.
 	 */
 	if (pgprot_val(ref_prot) & _PAGE_PRESENT)
-		pgprot_val(ref_prot) |= __PAGE_KERNEL_GLOBAL;
+		pgprot_val(ref_prot) |= _PAGE_GLOBAL;
 	else
-		pgprot_val(ref_prot) &= ~__PAGE_KERNEL_GLOBAL;
+		pgprot_val(ref_prot) &= ~_PAGE_GLOBAL;
 
 	/*
 	 * Get the target pfn from the original entry:
@@ -938,9 +938,9 @@ static void populate_pte(struct cpa_data
 	 * support it.
 	 */
 	if (pgprot_val(pgprot) & _PAGE_PRESENT)
-		pgprot_val(pgprot) |= __PAGE_KERNEL_GLOBAL;
+		pgprot_val(pgprot) |= _PAGE_GLOBAL;
 	else
-		pgprot_val(pgprot) &= ~__PAGE_KERNEL_GLOBAL;
+		pgprot_val(pgprot) &= ~_PAGE_GLOBAL;
 
 	pgprot = canon_pgprot(pgprot);
 
@@ -1242,9 +1242,9 @@ static int __change_page_attr(struct cpa
 		 * support it.
 		 */
 		if (pgprot_val(new_prot) & _PAGE_PRESENT)
-			pgprot_val(new_prot) |= __PAGE_KERNEL_GLOBAL;
+			pgprot_val(new_prot) |= _PAGE_GLOBAL;
 		else
-			pgprot_val(new_prot) &= ~__PAGE_KERNEL_GLOBAL;
+			pgprot_val(new_prot) &= ~_PAGE_GLOBAL;
 
 		/*
 		 * We need to keep the pfn from the existing PTE,