[RFC PATCH 45/56] x86/alternative: Use boot_cpu_has in ITS code

David Kaplan
2025-10-13T14:36:24Z

Replace cpu_feature_enabled with boot_cpu_has because under dynamic
re-patching, this code may be called after features have changed but before
alternatives are patched.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
---
arch/x86/kernel/alternative.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 2d48d750d4d9..5a543ffca10d 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -187,7 +187,7 @@ static void its_fini_core(void)
#ifdef CONFIG_MODULES
void its_init_mod(struct module *mod)
{
- if (!cpu_feature_enabled(X86_FEATURE_INDIRECT_THUNK_ITS))
+ if (!boot_cpu_has(X86_FEATURE_INDIRECT_THUNK_ITS))
return;

mutex_lock(&text_mutex);
@@ -197,7 +197,7 @@ void its_init_mod(struct module *mod)

void its_fini_mod(struct module *mod)
{
- if (!cpu_feature_enabled(X86_FEATURE_INDIRECT_THUNK_ITS))
+ if (!boot_cpu_has(X86_FEATURE_INDIRECT_THUNK_ITS))
return;

WARN_ON_ONCE(its_mod != mod);
@@ -901,7 +901,7 @@ static int emit_its_trampoline(void *addr, struct insn *insn, int reg, u8 *bytes
/* Check if an indirect branch is at ITS-unsafe address */
static bool cpu_wants_indirect_its_thunk_at(unsigned long addr, int reg)
{
- if (!cpu_feature_enabled(X86_FEATURE_INDIRECT_THUNK_ITS))
+ if (!boot_cpu_has(X86_FEATURE_INDIRECT_THUNK_ITS))
return false;

/* Indirect branch opcode is 2 or 3 bytes depending on reg */
@@ -967,9 +967,9 @@ static int patch_retpoline(void *addr, struct insn *insn, u8 *bytes)
/* If anyone ever does: CALL/JMP *%rsp, we're in deep trouble. */
BUG_ON(reg == 4);

- if (cpu_feature_enabled(X86_FEATURE_RETPOLINE) &&
- !cpu_feature_enabled(X86_FEATURE_RETPOLINE_LFENCE)) {
- if (cpu_feature_enabled(X86_FEATURE_CALL_DEPTH))
+ if (boot_cpu_has(X86_FEATURE_RETPOLINE) &&
+ !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE)) {
+ if (boot_cpu_has(X86_FEATURE_CALL_DEPTH))
return emit_call_track_retpoline(addr, insn, reg, bytes);

return -1;
@@ -1004,7 +1004,7 @@ static int patch_retpoline(void *addr, struct insn *insn, u8 *bytes)
/*
* For RETPOLINE_LFENCE: prepend the indirect CALL/JMP with an LFENCE.
*/
- if (cpu_feature_enabled(X86_FEATURE_RETPOLINE_LFENCE)) {
+ if (boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE)) {
bytes[i++] = 0x0f;
bytes[i++] = 0xae;
bytes[i++] = 0xe8; /* LFENCE */
--
2.34.1