[PATCH v2 18/21] arm64: KVM: Introduce hyp_alternate_value helper
From: Marc Zyngier <hidden>
Date: 2016-01-25 15:58:22
Also in:
kvm, kvmarm, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
We already have hyp_alternate_select() to define a function pointer that gets changed by a kernel feature or workaround. It would be useful to have a similar feature that resolves in a direct value, without requiring a function call. For this purpose, introduce hyp_alternate_value(), which returns one of two values depending on the state of the alternative. Signed-off-by: Marc Zyngier <redacted> --- arch/arm64/kvm/hyp/hyp.h | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/arch/arm64/kvm/hyp/hyp.h b/arch/arm64/kvm/hyp/hyp.h
index 44eaff7..dc75fdb 100644
--- a/arch/arm64/kvm/hyp/hyp.h
+++ b/arch/arm64/kvm/hyp/hyp.h@@ -144,6 +144,17 @@ typeof(orig) * __hyp_text fname(void) \ return val; \ } +#define hyp_alternate_value(fname, orig, alt, cond) \ +typeof(orig) __hyp_text fname(void) \ +{ \ + typeof(alt) val = orig; \ + asm volatile(ALTERNATIVE("nop \n", \ + "mov %0, %1 \n", \ + cond) \ + : "+r" (val) : "r" ((typeof(orig))alt)); \ + return val; \ +} + void __vgic_v2_save_state(struct kvm_vcpu *vcpu); void __vgic_v2_restore_state(struct kvm_vcpu *vcpu);
--
2.1.4