From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933190AbcAYP6W (ORCPT ); Mon, 25 Jan 2016 10:58:22 -0500 Received: from foss.arm.com ([217.140.101.70]:38565 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933211AbcAYPym (ORCPT ); Mon, 25 Jan 2016 10:54:42 -0500 From: Marc Zyngier To: Catalin Marinas , Will Deacon , Christoffer Dall Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Subject: [PATCH v2 18/21] arm64: KVM: Introduce hyp_alternate_value helper Date: Mon, 25 Jan 2016 15:53:52 +0000 Message-Id: <1453737235-16522-19-git-send-email-marc.zyngier@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1453737235-16522-1-git-send-email-marc.zyngier@arm.com> References: <1453737235-16522-1-git-send-email-marc.zyngier@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.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