From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave.Martin@arm.com (Dave Martin) Date: Tue, 8 May 2018 17:44:59 +0100 Subject: [PATCH v6 14/15] KVM: arm64: Fold redundant exit code checks out of fixup_guest_exit() In-Reply-To: <1525797900-5548-1-git-send-email-Dave.Martin@arm.com> References: <1525797900-5548-1-git-send-email-Dave.Martin@arm.com> Message-ID: <1525797900-5548-15-git-send-email-Dave.Martin@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The entire tail of fixup_guest_exit() is contained in if statements of the form if (x && *exit_code == ARM_EXCEPTION_TRAP). As a result, we can check just once and bail out of the function early, allowing the remaining if conditions to be simplified. The only awkward case is where *exit_code is changed to ARM_EXCEPTION_EL1_SERROR in the case of an illegal GICv2 CPU interface access: in that case, the GICv3 trap handling code is skipped using a goto. This avoids pointlessly evaluating the static branch check for the GICv3 case, even though we can't have vgic_v2_cpuif_trap and vgic_v3_cpuif_trap true simultaneously unless we have a GICv3 and GICv2 on the host: that sounds stupid, but I haven't satisfied myself that it can't happen. No functional change. Signed-off-by: Dave Martin --- Changes since v5: Requested by Marc Zyngier: * Move "goto exit" to the end of the data abort handling code under gicv2 cpuif trap handling, since the gicv3-specific handling is only for sysreg traps. --- arch/arm64/kvm/hyp/switch.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c index 21e5543..5be472d 100644 --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -386,11 +386,13 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) * same PC once the SError has been injected, and replay the * trapping instruction. */ - if (*exit_code == ARM_EXCEPTION_TRAP && !__populate_fault_info(vcpu)) + if (*exit_code != ARM_EXCEPTION_TRAP) + goto exit; + + if (!__populate_fault_info(vcpu)) return true; - if (static_branch_unlikely(&vgic_v2_cpuif_trap) && - *exit_code == ARM_EXCEPTION_TRAP) { + if (static_branch_unlikely(&vgic_v2_cpuif_trap)) { bool valid; valid = kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_DABT_LOW && @@ -416,11 +418,12 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; *exit_code = ARM_EXCEPTION_EL1_SERROR; } + + goto exit; } } if (static_branch_unlikely(&vgic_v3_cpuif_trap) && - *exit_code == ARM_EXCEPTION_TRAP && (kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_SYS64 || kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_CP15_32)) { int ret = __vgic_v3_perform_cpuif_access(vcpu); @@ -429,6 +432,7 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) return true; } +exit: /* Return to the host kernel and handle the exit */ return false; } -- 2.1.4