From patchwork Sun Mar 17 14:36:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zenghui Yu X-Patchwork-Id: 10856375 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4F73B1669 for ; Sun, 17 Mar 2019 14:42:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 345A929376 for ; Sun, 17 Mar 2019 14:42:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 23BD929379; Sun, 17 Mar 2019 14:42:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BDC1529376 for ; Sun, 17 Mar 2019 14:42:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727043AbfCQOlq (ORCPT ); Sun, 17 Mar 2019 10:41:46 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:4696 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726850AbfCQOlp (ORCPT ); Sun, 17 Mar 2019 10:41:45 -0400 Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 20EB82B4E8D95F57C411; Sun, 17 Mar 2019 22:41:42 +0800 (CST) Received: from HGHY2Y004646261.china.huawei.com (10.184.12.158) by DGGEMS413-HUB.china.huawei.com (10.3.19.213) with Microsoft SMTP Server id 14.3.408.0; Sun, 17 Mar 2019 22:41:34 +0800 From: Zenghui Yu To: , , , CC: , , , , , , , , , , , Zenghui Yu Subject: [RFC PATCH] KVM: arm/arm64: Enable direct irqfd MSI injection Date: Sun, 17 Mar 2019 14:36:13 +0000 Message-ID: <1552833373-19828-1-git-send-email-yuzenghui@huawei.com> X-Mailer: git-send-email 2.6.4.windows.1 MIME-Version: 1.0 X-Originating-IP: [10.184.12.158] X-CFilter-Loop: Reflected Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently, IRQFD on arm still uses the deferred workqueue mechanism to inject interrupts into guest, which will likely lead to a busy context-switching from/to the kworker thread. This overhead is for no purpose (only in my view ...) and will result in an interrupt performance degradation. Implement kvm_arch_set_irq_inatomic() for arm/arm64 to support direct irqfd MSI injection, by which we can get rid of the annoying latency. As a result, irqfd MSI intensive scenarios (e.g., DPDK with high packet processing workloads) will benefit from it. Signed-off-by: Zenghui Yu --- It seems that only MSI will follow the IRQFD path, did I miss something? This patch is still under test and sent out for early feedback. If I have any mis-understanding, please fix me up and let me know. Thanks! --- virt/kvm/arm/vgic/trace.h | 22 ++++++++++++++++++++++ virt/kvm/arm/vgic/vgic-irqfd.c | 21 +++++++++++++++++++++ 2 files changed, 43 insertions(+) diff --git a/virt/kvm/arm/vgic/trace.h b/virt/kvm/arm/vgic/trace.h index 55fed77..bc1f4db 100644 --- a/virt/kvm/arm/vgic/trace.h +++ b/virt/kvm/arm/vgic/trace.h @@ -27,6 +27,28 @@ __entry->vcpu_id, __entry->irq, __entry->level) ); +TRACE_EVENT(kvm_arch_set_irq_inatomic, + TP_PROTO(u32 gsi, u32 type, int level, int irq_source_id), + TP_ARGS(gsi, type, level, irq_source_id), + + TP_STRUCT__entry( + __field( u32, gsi ) + __field( u32, type ) + __field( int, level ) + __field( int, irq_source_id ) + ), + + TP_fast_assign( + __entry->gsi = gsi; + __entry->type = type; + __entry->level = level; + __entry->irq_source_id = irq_source_id; + ), + + TP_printk("gsi %u type %u level %d source %d", __entry->gsi, + __entry->type, __entry->level, __entry->irq_source_id) +); + #endif /* _TRACE_VGIC_H */ #undef TRACE_INCLUDE_PATH diff --git a/virt/kvm/arm/vgic/vgic-irqfd.c b/virt/kvm/arm/vgic/vgic-irqfd.c index 99e026d..4cfc3f4 100644 --- a/virt/kvm/arm/vgic/vgic-irqfd.c +++ b/virt/kvm/arm/vgic/vgic-irqfd.c @@ -19,6 +19,7 @@ #include #include #include "vgic.h" +#include "trace.h" /** * vgic_irqfd_set_irq: inject the IRQ corresponding to the @@ -105,6 +106,26 @@ int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e, return vgic_its_inject_msi(kvm, &msi); } +/** + * kvm_arch_set_irq_inatomic: fast-path for irqfd injection + * + * Currently only direct MSI injecton is supported. + */ +int kvm_arch_set_irq_inatomic(struct kvm_kernel_irq_routing_entry *e, + struct kvm *kvm, int irq_source_id, int level, + bool line_status) +{ + int ret; + + trace_kvm_arch_set_irq_inatomic(e->gsi, e->type, level, irq_source_id); + + if (unlikely(e->type != KVM_IRQ_ROUTING_MSI)) + return -EWOULDBLOCK; + + ret = kvm_set_msi(e, kvm, irq_source_id, level, line_status); + return ret; +} + int kvm_vgic_setup_default_irq_routing(struct kvm *kvm) { struct kvm_irq_routing_entry *entries;