From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Mon, 25 Jan 2016 15:53:52 +0000 Subject: [PATCH v2 18/21] arm64: KVM: Introduce hyp_alternate_value helper In-Reply-To: <1453737235-16522-1-git-send-email-marc.zyngier@arm.com> References: <1453737235-16522-1-git-send-email-marc.zyngier@arm.com> Message-ID: <1453737235-16522-19-git-send-email-marc.zyngier@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 --- 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