Commit 2d1435b7 authored by Sean Christopherson's avatar Sean Christopherson Committed by Peter Zijlstra
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x86/fred: Install system vector handlers even if FRED isn't fully enabled 



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: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250714103441.121251108@infradead.org
parent c8ed0812

arch/x86/include/asm/idtentry.h

+2 −7
Original line number Diff line number Diff line
@@ -460,17 +460,12 @@ __visible noinstr void func(struct pt_regs *regs, \ 
#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);		\

}

arch/x86/kernel/irqinit.c

+4 −2
Original line number Diff line number Diff line
@@ -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();