Patch "x86/paravirt: Remove 'noreplace-paravirt' cmdline option" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

x86/paravirt: Remove 'noreplace-paravirt' cmdline option

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86paravirt_Remove_noreplace-paravirt_cmdline_option.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Subject: x86/paravirt: Remove 'noreplace-paravirt' cmdline option
From: Josh Poimboeuf [email protected]
Date: Tue Jan 30 22:13:33 2018 -0600

From: Josh Poimboeuf [email protected]

commit 12c69f1e94c89d40696e83804dd2f0965b5250cd

The 'noreplace-paravirt' option disables paravirt patching, leaving the original pv indirect calls in place.

That's highly incompatible with retpolines, unless we want to uglify paravirt even further and convert the paravirt calls to retpolines.

As far as I can tell, the option doesn't seem to be useful for much other than introducing surprising corner cases and making the kernel vulnerable to Spectre v2. It was probably a debug option from the early paravirt days. So just remove it.

---
 Documentation/admin-guide/kernel-parameters.txt |    2 --
 arch/x86/kernel/alternative.c                   |   14 --------------
 2 files changed, 16 deletions(-)

@@ -2742,8 +2742,6 @@
 	norandmaps	Don't use address space randomization.  Equivalent to
 			echo 0 > /proc/sys/kernel/randomize_va_space
 
-	noreplace-paravirt	[X86,IA-64,PV_OPS] Don't patch paravirt_ops
-
 	noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
 			with UP alternatives
 

@@ -46,17 +46,6 @@ static int __init setup_noreplace_smp(ch
 }
 __setup("noreplace-smp", setup_noreplace_smp);
 
-#ifdef CONFIG_PARAVIRT
-static int __initdata_or_module noreplace_paravirt = 0;
-
-static int __init setup_noreplace_paravirt(char *str)
-{
-	noreplace_paravirt = 1;
-	return 1;
-}
-__setup("noreplace-paravirt", setup_noreplace_paravirt);
-#endif
-
 #define DPRINTK(fmt, args...)						\
 do {									\
 	if (debug_alternative)						\

@@ -599,9 +588,6 @@ void __init_or_module apply_paravirt(str
 	struct paravirt_patch_site *p;
 	char insnbuf[MAX_PATCH_LEN];
 
-	if (noreplace_paravirt)
-		return;
-
 	for (p = start; p < end; p++) {
 		unsigned int used;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/objtool_Add_support_for_alternatives_at_the_end_of_a_section.patch queue-4.15/x86paravirt_Remove_noreplace-paravirt_cmdline_option.patch queue-4.15/KVM_VMX_Make_indirect_call_speculation_safe.patch queue-4.15/x86alternative_Print_unadorned_pointers.patch queue-4.15/x86bugs_Drop_one_mitigation_from_dmesg.patch queue-4.15/x86nospec_Fix_header_guards_names.patch queue-4.15/KVM_x86_Make_indirect_calls_in_emulator_speculation_safe.patch queue-4.15/objtool_Warn_on_stripped_section_symbol.patch queue-4.15/objtool_Improve_retpoline_alternative_handling.patch