[PATCH 1/2] x86/fred: Always install system interrupt handler into IDT

[Hou Wenlong]

In sysvec_install(), the system interrupt handler is not installed into
the IDT when the FRED feature is present, but FRED can be disabled
in trap_init(). However, sysvec_install() can be used
before trap_init(), e.g., the HYPERVISOR_CALLBACK_VECTOR handler is
registered in kvm_guest_init(), which is called by setup_arch() before
trap_init(). If FRED is disabled later, then the spurious_interrupt()
handler will be used due to the handler not being installed into the
IDT. Therefore, always install system interrupt handler into IDT.

Fixes: 3810da12710a ("x86/fred: Add a fred= cmdline param")
Signed-off-by: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx>
---
 arch/x86/include/asm/idtentry.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index d4f24499b256..daee9f7765bc 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -470,8 +470,7 @@ static inline void fred_install_sysvec(unsigned int vector, const idtentry_t fun
 #define sysvec_install(vector, function) {				\
 	if (cpu_feature_enabled(X86_FEATURE_FRED))			\
 		fred_install_sysvec(vector, function);			\
-	else								\
-		idt_install_sysvec(vector, asm_##function);		\
+	idt_install_sysvec(vector, asm_##function);			\
 }
 
 #else /* !__ASSEMBLY__ */
-- 
2.31.1