Merge tag 'v5.8-rc4' into for-5.9/drivers

Merge in 5.8-rc4 for-5.9/block to setup for-5.9/drivers, to provide
a clean base and making the life for the NVMe changes easier.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

* tag 'v5.8-rc4': (732 commits)
  Linux 5.8-rc4
  x86/ldt: use "pr_info_once()" instead of open-coding it badly
  MIPS: Do not use smp_processor_id() in preemptible code
  MIPS: Add missing EHB in mtc0 -> mfc0 sequence for DSPen
  .gitignore: Do not track `defconfig` from `make savedefconfig`
  io_uring: fix regression with always ignoring signals in io_cqring_wait()
  x86/ldt: Disable 16-bit segments on Xen PV
  x86/entry/32: Fix #MC and #DB wiring on x86_32
  x86/entry/xen: Route #DB correctly on Xen PV
  x86/entry, selftests: Further improve user entry sanity checks
  x86/entry/compat: Clear RAX high bits on Xen PV SYSENTER
  i2c: mlxcpld: check correct size of maximum RECV_LEN packet
  i2c: add Kconfig help text for slave mode
  i2c: slave-eeprom: update documentation
  i2c: eg20t: Load module automatically if ID matches
  i2c: designware: platdrv: Set class based on DMI
  i2c: algo-pca: Add 0x78 as SCL stuck low status for PCA9665
  mm/page_alloc: fix documentation error
  vmalloc: fix the owner argument for the new __vmalloc_node_range callers
  mm/cma.c: use exact_nid true to fix possible per-numa cma leak
  ...

1 files changed, 12 insertions, 12 deletions

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 043d93cdcaad..95c090a45b4b 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -347,6 +347,9 @@ out:
 	cr4_clear_bits(X86_CR4_UMIP);
 }
 
+/* These bits should not change their value after CPU init is finished. */
+static const unsigned long cr4_pinned_mask =
+	X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_UMIP | X86_CR4_FSGSBASE;
 static DEFINE_STATIC_KEY_FALSE_RO(cr_pinning);
 static unsigned long cr4_pinned_bits __ro_after_init;
 
@@ -371,20 +374,20 @@ EXPORT_SYMBOL(native_write_cr0);
 
 void native_write_cr4(unsigned long val)
 {
-	unsigned long bits_missing = 0;
+	unsigned long bits_changed = 0;
 
 set_register:
 	asm volatile("mov %0,%%cr4": "+r" (val), "+m" (cr4_pinned_bits));
 
 	if (static_branch_likely(&cr_pinning)) {
-		if (unlikely((val & cr4_pinned_bits) != cr4_pinned_bits)) {
-			bits_missing = ~val & cr4_pinned_bits;
-			val |= bits_missing;
+		if (unlikely((val & cr4_pinned_mask) != cr4_pinned_bits)) {
+			bits_changed = (val & cr4_pinned_mask) ^ cr4_pinned_bits;
+			val = (val & ~cr4_pinned_mask) | cr4_pinned_bits;
 			goto set_register;
 		}
-		/* Warn after we've set the missing bits. */
-		WARN_ONCE(bits_missing, "CR4 bits went missing: %lx!?\n",
-			  bits_missing);
+		/* Warn after we've corrected the changed bits. */
+		WARN_ONCE(bits_changed, "pinned CR4 bits changed: 0x%lx!?\n",
+			  bits_changed);
 	}
 }
 #if IS_MODULE(CONFIG_LKDTM)
@@ -419,7 +422,7 @@ void cr4_init(void)
 	if (boot_cpu_has(X86_FEATURE_PCID))
 		cr4 |= X86_CR4_PCIDE;
 	if (static_branch_likely(&cr_pinning))
-		cr4 |= cr4_pinned_bits;
+		cr4 = (cr4 & ~cr4_pinned_mask) | cr4_pinned_bits;
 
 	__write_cr4(cr4);
 
@@ -434,10 +437,7 @@ void cr4_init(void)
  */
 static void __init setup_cr_pinning(void)
 {
-	unsigned long mask;
-
-	mask = (X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_UMIP);
-	cr4_pinned_bits = this_cpu_read(cpu_tlbstate.cr4) & mask;
+	cr4_pinned_bits = this_cpu_read(cpu_tlbstate.cr4) & cr4_pinned_mask;
 	static_key_enable(&cr_pinning.key);
 }