From patchwork Mon Sep 9 13:47:58 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 11137975 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 649FF14E5 for ; Mon, 9 Sep 2019 13:49:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 43DF321920 for ; Mon, 9 Sep 2019 13:49:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568036953; bh=JHeiPDRhKs+cohjC2m4uKlvj7IQf2DYpLNr0bwcNG8A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rlkKHAutp1AqRNF9+5M01WG8pVyVpc6SkR0N4l1tMLi7PEbEIWXsMF1ndrwWulEqU We4+s2IJv0iCgRKIIr+hpalxWwI6EHE9c8haHIhB5CdMHL3HMwUEArUzY5ZMub1+yC E7/FLs7rJYGJp0z1yBKLE6hfv0fU7y6+sjcxsQog= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404908AbfIINtM (ORCPT ); Mon, 9 Sep 2019 09:49:12 -0400 Received: from foss.arm.com ([217.140.110.172]:50646 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404887AbfIINtM (ORCPT ); Mon, 9 Sep 2019 09:49:12 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 705771713; Mon, 9 Sep 2019 06:49:11 -0700 (PDT) Received: from localhost.localdomain (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 37F293F59C; Mon, 9 Sep 2019 06:49:09 -0700 (PDT) From: Marc Zyngier To: Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= Cc: Alexandru Elisei , Andre Przywara , Eric Auger , James Morse , Mark Rutland , Zenghui Yu , kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: [PATCH 08/17] KVM: arm/arm64: vgic-its: Cache successful MSI->LPI translation Date: Mon, 9 Sep 2019 14:47:58 +0100 Message-Id: <20190909134807.27978-9-maz@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190909134807.27978-1-maz@kernel.org> References: <20190909134807.27978-1-maz@kernel.org> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On a successful translation, preserve the parameters in the LPI translation cache. Each translation is reusing the last slot in the list, naturally evicting the least recently used entry. Tested-by: Andre Przywara Reviewed-by: Eric Auger Signed-off-by: Marc Zyngier --- virt/kvm/arm/vgic/vgic-its.c | 86 ++++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c index d3e90a9d0a7a..e61d3ea0ab40 100644 --- a/virt/kvm/arm/vgic/vgic-its.c +++ b/virt/kvm/arm/vgic/vgic-its.c @@ -535,6 +535,90 @@ static unsigned long vgic_mmio_read_its_idregs(struct kvm *kvm, return 0; } +static struct vgic_irq *__vgic_its_check_cache(struct vgic_dist *dist, + phys_addr_t db, + u32 devid, u32 eventid) +{ + struct vgic_translation_cache_entry *cte; + + list_for_each_entry(cte, &dist->lpi_translation_cache, entry) { + /* + * If we hit a NULL entry, there is nothing after this + * point. + */ + if (!cte->irq) + break; + + if (cte->db != db || cte->devid != devid || + cte->eventid != eventid) + continue; + + /* + * Move this entry to the head, as it is the most + * recently used. + */ + if (!list_is_first(&cte->entry, &dist->lpi_translation_cache)) + list_move(&cte->entry, &dist->lpi_translation_cache); + + return cte->irq; + } + + return NULL; +} + +static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its, + u32 devid, u32 eventid, + struct vgic_irq *irq) +{ + struct vgic_dist *dist = &kvm->arch.vgic; + struct vgic_translation_cache_entry *cte; + unsigned long flags; + phys_addr_t db; + + /* Do not cache a directly injected interrupt */ + if (irq->hw) + return; + + raw_spin_lock_irqsave(&dist->lpi_list_lock, flags); + + if (unlikely(list_empty(&dist->lpi_translation_cache))) + goto out; + + /* + * We could have raced with another CPU caching the same + * translation behind our back, so let's check it is not in + * already + */ + db = its->vgic_its_base + GITS_TRANSLATER; + if (__vgic_its_check_cache(dist, db, devid, eventid)) + goto out; + + /* Always reuse the last entry (LRU policy) */ + cte = list_last_entry(&dist->lpi_translation_cache, + typeof(*cte), entry); + + /* + * Caching the translation implies having an extra reference + * to the interrupt, so drop the potential reference on what + * was in the cache, and increment it on the new interrupt. + */ + if (cte->irq) + __vgic_put_lpi_locked(kvm, cte->irq); + + vgic_get_irq_kref(irq); + + cte->db = db; + cte->devid = devid; + cte->eventid = eventid; + cte->irq = irq; + + /* Move the new translation to the head of the list */ + list_move(&cte->entry, &dist->lpi_translation_cache); + +out: + raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags); +} + void vgic_its_invalidate_cache(struct kvm *kvm) { struct vgic_dist *dist = &kvm->arch.vgic; @@ -578,6 +662,8 @@ int vgic_its_resolve_lpi(struct kvm *kvm, struct vgic_its *its, if (!vcpu->arch.vgic_cpu.lpis_enabled) return -EBUSY; + vgic_its_cache_translation(kvm, its, devid, eventid, ite->irq); + *irq = ite->irq; return 0; }