[patch V2 1/5] x86/kaiser: Respect disabled CPU features

[Thomas Gleixner <tglx@linutronix.de>]

[-- Attachment #1: x86-kaiser--Respect-disabled-features.patch --]
[-- Type: text/plain, Size: 2185 bytes --]

PAGE_NX and PAGE_GLOBAL might be not supported or disabled on the command
line, but KAISER sets them unconditionally.

Add proper protection against that.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/pgtable_64.h |    3 ++-
 arch/x86/mm/kaiser.c              |   12 +++++++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -222,7 +222,8 @@ static inline pgd_t kaiser_set_shadow_pg
 			 * wrong CR3 value, userspace will crash
 			 * instead of running.
 			 */
-			pgd.pgd |= _PAGE_NX;
+			if (__supported_pte_mask & _PAGE_NX)
+				pgd.pgd |= _PAGE_NX;
 		}
 	} else if (pgd_userspace_access(*pgdp)) {
 		/*
--- a/arch/x86/mm/kaiser.c
+++ b/arch/x86/mm/kaiser.c
@@ -42,6 +42,8 @@
 
 #define KAISER_WALK_ATOMIC  0x1
 
+static pteval_t kaiser_pte_mask __ro_after_init = ~(_PAGE_NX | _PAGE_GLOBAL);
+
 /*
  * At runtime, the only things we map are some things for CPU
  * hotplug, and stacks for new processes.  No two CPUs will ever
@@ -244,11 +246,14 @@ static pte_t *kaiser_shadow_pagetable_wa
 int kaiser_add_user_map(const void *__start_addr, unsigned long size,
 			unsigned long flags)
 {
-	pte_t *pte;
 	unsigned long start_addr = (unsigned long)__start_addr;
 	unsigned long address = start_addr & PAGE_MASK;
 	unsigned long end_addr = PAGE_ALIGN(start_addr + size);
 	unsigned long target_address;
+	pte_t *pte;
+
+	/* Clear not supported bits */
+	flags &= kaiser_pte_mask;
 
 	for (; address < end_addr; address += PAGE_SIZE) {
 		target_address = get_pa_from_kernel_map(address);
@@ -308,6 +313,11 @@ static void __init kaiser_init_all_pgds(
 	pgd_t *pgd;
 	int i;
 
+	if (__supported_pte_mask & _PAGE_NX)
+		kaiser_pte_mask |= _PAGE_NX;
+	if (boot_cpu_has(X86_FEATURE_PGE))
+		kaiser_pte_mask |= _PAGE_GLOBAL;
+
 	pgd = kernel_to_shadow_pgdp(pgd_offset_k(0UL));
 	for (i = PTRS_PER_PGD / 2; i < PTRS_PER_PGD; i++) {
 		/*


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