From patchwork Thu Nov 7 16:04:12 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 11233265 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4200D1575 for ; Thu, 7 Nov 2019 16:04:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 21AA221D7E for ; Thu, 7 Nov 2019 16:04:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573142666; bh=suC2OQUgMmr5U4RxMs3eaOS5/M8Api1Y3jH3tP/IubQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=x5uEIx1NIG6Cl3qMOjT8dQg3JoSL6zC24UDhGaMYF8caBxPoONt2mQEIVSozqieWk VPpJIHPY7iiGbogF5F/D4+gaot7TYisRiot3dhX0VX3sHzpABtdMQyS2kjbvCM5LTV RMt7AHS3LtyeJ89J6nQ64gIlR0reH6+x8C4DsDUY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388659AbfKGQEZ (ORCPT ); Thu, 7 Nov 2019 11:04:25 -0500 Received: from inca-roads.misterjones.org ([213.251.177.50]:35362 "EHLO inca-roads.misterjones.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387470AbfKGQEY (ORCPT ); Thu, 7 Nov 2019 11:04:24 -0500 Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by cheepnis.misterjones.org with esmtpsa (TLSv1.2:DHE-RSA-AES128-GCM-SHA256:128) (Exim 4.80) (envelope-from ) id 1iSkGk-0008Bm-Vh; Thu, 07 Nov 2019 17:04:23 +0100 From: Marc Zyngier To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Cc: James Morse , Julien Thierry , Suzuki K Poulose Subject: [PATCH 2/2] KVM: arm64: Opportunistically turn off WFI trapping when using direct LPI injection Date: Thu, 7 Nov 2019 16:04:12 +0000 Message-Id: <20191107160412.30301-3-maz@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191107160412.30301-1-maz@kernel.org> References: <20191107160412.30301-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on cheepnis.misterjones.org); SAEximRunCond expanded to false Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Just like we do for WFE trapping, it can be useful to turn off WFI trapping when the physical CPU is not oversubscribed (that is, the vcpu is the only runnable process on this CPU) *and* that we're using direct injection of interrupts. The conditions are reevaluated on each vcpu_load(), ensuring that we don't switch to this mode on a busy system. On a GICv4 system, this has the effect of reducing the generation of doorbell interrupts to zero when the right conditions are met, which is a huge improvement over the current situation (where the doorbells are screaming if the CPU ever hits a blocking WFI). Signed-off-by: Marc Zyngier Reviewed-by: Zenghui Yu --- arch/arm/include/asm/kvm_emulate.h | 4 ++-- arch/arm64/include/asm/kvm_emulate.h | 9 +++++++-- virt/kvm/arm/arm.c | 4 ++-- 3 files changed, 11 insertions(+), 6 deletions(-) diff --git a/arch/arm/include/asm/kvm_emulate.h b/arch/arm/include/asm/kvm_emulate.h index e8ef349c04b4..9b118516d2db 100644 --- a/arch/arm/include/asm/kvm_emulate.h +++ b/arch/arm/include/asm/kvm_emulate.h @@ -95,12 +95,12 @@ static inline unsigned long *vcpu_hcr(const struct kvm_vcpu *vcpu) return (unsigned long *)&vcpu->arch.hcr; } -static inline void vcpu_clear_wfe_traps(struct kvm_vcpu *vcpu) +static inline void vcpu_clear_wfx_traps(struct kvm_vcpu *vcpu) { vcpu->arch.hcr &= ~HCR_TWE; } -static inline void vcpu_set_wfe_traps(struct kvm_vcpu *vcpu) +static inline void vcpu_set_wfx_traps(struct kvm_vcpu *vcpu) { vcpu->arch.hcr |= HCR_TWE; } diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index 7b835337f78b..5efe5ca8fecf 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -87,14 +87,19 @@ static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu) return (unsigned long *)&vcpu->arch.hcr_el2; } -static inline void vcpu_clear_wfe_traps(struct kvm_vcpu *vcpu) +static inline void vcpu_clear_wfx_traps(struct kvm_vcpu *vcpu) { vcpu->arch.hcr_el2 &= ~HCR_TWE; + if (atomic_read(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vlpi_count)) + vcpu->arch.hcr_el2 &= ~HCR_TWI; + else + vcpu->arch.hcr_el2 |= HCR_TWI; } -static inline void vcpu_set_wfe_traps(struct kvm_vcpu *vcpu) +static inline void vcpu_set_wfx_traps(struct kvm_vcpu *vcpu) { vcpu->arch.hcr_el2 |= HCR_TWE; + vcpu->arch.hcr_el2 |= HCR_TWI; } static inline void vcpu_ptrauth_enable(struct kvm_vcpu *vcpu) diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 4d07c968467a..12e0280291ce 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -416,9 +416,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) kvm_make_request(KVM_REQ_RECORD_STEAL, vcpu); if (single_task_running()) - vcpu_clear_wfe_traps(vcpu); + vcpu_clear_wfx_traps(vcpu); else - vcpu_set_wfe_traps(vcpu); + vcpu_set_wfx_traps(vcpu); vcpu_ptrauth_setup_lazy(vcpu); }