From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20A86C433E0 for ; Thu, 14 Jan 2021 10:18:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C5E2323A3B for ; Thu, 14 Jan 2021 10:18:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728549AbhANKSF (ORCPT ); Thu, 14 Jan 2021 05:18:05 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:45842 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726283AbhANKSD (ORCPT ); Thu, 14 Jan 2021 05:18:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610619397; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IaIUvaMv2k9j6w56+5o78W95fqxpiStrTQ2Nmkvuj38=; b=FMtLrxd3/18QRvfQO4SCsw46Eozxo51kzL3KmCDCzx9/v9emhPOBQhFBcS1zVZSZc+mssD T/uMjgTlqAm0bV7I0TeY8RiRlpGvLQ6W8c7hojjmNkPlDSpaHzx6IDaaZ2zy6qukYMvH/t VfnrzLdjg1H/oOwkxMXUC9vJ1tc2cMA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-156-5iw1vXHqMKWXyi8cUWxbLg-1; Thu, 14 Jan 2021 05:16:33 -0500 X-MC-Unique: 5iw1vXHqMKWXyi8cUWxbLg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EB979107ACFB; Thu, 14 Jan 2021 10:16:31 +0000 (UTC) Received: from [10.36.114.165] (ovpn-114-165.ams2.redhat.com [10.36.114.165]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 05D4019C47; Thu, 14 Jan 2021 10:16:28 +0000 (UTC) Subject: Re: [PATCH 8/9] KVM: arm64: vgic-v3: Expose GICR_TYPER.Last for userspace To: Alexandru Elisei , eric.auger.pro@gmail.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, maz@kernel.org, drjones@redhat.com Cc: james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, shuah@kernel.org, pbonzini@redhat.com References: <20201212185010.26579-1-eric.auger@redhat.com> <20201212185010.26579-9-eric.auger@redhat.com> <45a364ec-eac6-a04b-9654-e97970186839@arm.com> From: Auger Eric Message-ID: <7078b0a5-fb18-5e65-953a-8a55009aa2be@redhat.com> Date: Thu, 14 Jan 2021 11:16:27 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <45a364ec-eac6-a04b-9654-e97970186839@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Alexandru, On 1/12/21 6:02 PM, Alexandru Elisei wrote: > Hi Eric, > > On 12/12/20 6:50 PM, Eric Auger wrote: >> Commit 23bde34771f1 ("KVM: arm64: vgic-v3: Drop the >> reporting of GICR_TYPER.Last for userspace") temporarily fixed >> a bug identified when attempting to access the GICR_TYPER >> register before the redistributor region setting but dropped >> the support of the LAST bit. This patch restores its >> support (if the redistributor region was set) while keeping the >> code safe. > > I suppose the reason for emulating GICR_TYPER.Last is for architecture compliance, > right? I think that should be in the commit message. OK added this in the commit msg. > >> >> Signed-off-by: Eric Auger >> --- >> arch/arm64/kvm/vgic/vgic-mmio-v3.c | 7 ++++++- >> include/kvm/arm_vgic.h | 1 + >> 2 files changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c >> index 581f0f490000..2f9ef6058f6e 100644 >> --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c >> +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c >> @@ -277,6 +277,8 @@ static unsigned long vgic_uaccess_read_v3r_typer(struct kvm_vcpu *vcpu, >> gpa_t addr, unsigned int len) >> { >> unsigned long mpidr = kvm_vcpu_get_mpidr_aff(vcpu); >> + struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu; >> + struct vgic_redist_region *rdreg = vgic_cpu->rdreg; >> int target_vcpu_id = vcpu->vcpu_id; >> u64 value; >> >> @@ -286,7 +288,9 @@ static unsigned long vgic_uaccess_read_v3r_typer(struct kvm_vcpu *vcpu, >> if (vgic_has_its(vcpu->kvm)) >> value |= GICR_TYPER_PLPIS; >> >> - /* reporting of the Last bit is not supported for userspace */ >> + if (rdreg && (vgic_cpu->rdreg_index == (rdreg->free_index - 1))) >> + value |= GICR_TYPER_LAST; >> + >> return extract_bytes(value, addr & 7, len); >> } >> >> @@ -714,6 +718,7 @@ int vgic_register_redist_iodev(struct kvm_vcpu *vcpu) >> return -EINVAL; >> >> vgic_cpu->rdreg = rdreg; >> + vgic_cpu->rdreg_index = rdreg->free_index; > > What happens if the next redistributor region we register has the base address > adjacent to this one? > > I'm really not familiar with the code, but is it not possible to create two > Redistributor regions (via > KVM_DEV_ARM_VGIC_GRP_ADDR(KVM_VGIC_V3_ADDR_TYPE_REDIST)) where the second > Redistributor region start address is immediately after the last Redistributor in > the preceding region? KVM_VGIC_V3_ADDR_TYPE_REDIST only allows to create a single rdist region. Only KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION allows to register several of them. with KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION, it is possible to register adjacent rdist regions. vgic_v3_rdist_free_slot() previously returned the 1st rdist region where enough space remains for inserting the new reg. We put the rdist at the free index there. But maybe I misunderstood your question? Thanks Eric > > Thanks, > Alex >> >> rd_base = rdreg->base + rdreg->free_index * KVM_VGIC_V3_REDIST_SIZE; >> >> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h >> index a8d8fdcd3723..596c069263a7 100644 >> --- a/include/kvm/arm_vgic.h >> +++ b/include/kvm/arm_vgic.h >> @@ -322,6 +322,7 @@ struct vgic_cpu { >> */ >> struct vgic_io_device rd_iodev; >> struct vgic_redist_region *rdreg; >> + u32 rdreg_index; >> >> /* Contains the attributes and gpa of the LPI pending tables. */ >> u64 pendbaser; >