From: Sean Christopherson <seanjc@xxxxxxxxxx>
Install the system vector IRQ handlers for FRED even if FRED isn't fully
enabled in hardware. This will allow KVM to use the FRED IRQ path even
on non-FRED hardware, which in turn will eliminate a non-CFI indirect CALL
(KVM currently invokes the IRQ handler via an IDT lookup on the vector).
[sean: extract from diff, drop stub, write changelog]
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/x86/include/asm/idtentry.h | 9 ++-------
arch/x86/kernel/irqinit.c | 6 ++++--
2 files changed, 6 insertions(+), 9 deletions(-)
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -460,17 +460,12 @@ __visible noinstr void func(struct pt_re
#endif
void idt_install_sysvec(unsigned int n, const void *function);
-
-#ifdef CONFIG_X86_FRED
void fred_install_sysvec(unsigned int vector, const idtentry_t function);
-#else
-static inline void fred_install_sysvec(unsigned int vector, const idtentry_t function) { }
-#endif
#define sysvec_install(vector, function) { \
- if (cpu_feature_enabled(X86_FEATURE_FRED)) \
+ if (IS_ENABLED(CONFIG_X86_FRED)) \
fred_install_sysvec(vector, function); \
- else \
+ if (!cpu_feature_enabled(X86_FEATURE_FRED)) \
idt_install_sysvec(vector, asm_##function); \
}
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -97,9 +97,11 @@ void __init native_init_IRQ(void)
/* Execute any quirks before the call gates are initialised: */
x86_init.irqs.pre_vector_init();
- if (cpu_feature_enabled(X86_FEATURE_FRED))
+ /* FRED's IRQ path may be used even if FRED isn't fully enabled. */
+ if (IS_ENABLED(CONFIG_X86_FRED))
fred_complete_exception_setup();
- else
+
+ if (!cpu_feature_enabled(X86_FEATURE_FRED))
idt_setup_apic_and_irq_gates();
lapic_assign_system_vectors();
