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 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0D7E1EB64DA for ; Fri, 7 Jul 2023 11:17:20 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.560419.876338 (Exim 4.92) (envelope-from ) id 1qHjSF-0003pN-BS; Fri, 07 Jul 2023 11:16:51 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 560419.876338; Fri, 07 Jul 2023 11:16:51 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qHjSF-0003pG-8l; Fri, 07 Jul 2023 11:16:51 +0000 Received: by outflank-mailman (input) for mailman id 560419; Fri, 07 Jul 2023 11:16:50 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qHjSE-0003pA-Rv for xen-devel@lists.xenproject.org; Fri, 07 Jul 2023 11:16:50 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qHjSC-00085b-Kf; Fri, 07 Jul 2023 11:16:48 +0000 Received: from 54-240-197-233.amazon.com ([54.240.197.233] helo=[192.168.10.48]) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1qHjSC-0002C2-ET; Fri, 07 Jul 2023 11:16:48 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID; bh=Vcgc35YhzH8xHKYXv2MOXHhuIFNryBkOC3PAhajBxwU=; b=hFeIprxoen0asxzReE5bzs9TQV 0m5U6ilb+MbiCuEn1yWBqk/L2FAYfBfCghjWUI2OMOJmmI8D2LyzKHz5i39Yh7nna4cymDuOPNR+3 Tio/a1aRQ4hsuyt25dA5MPHskSqYnHqMRnYggln8BIK6jjbkSh9H+/qB/iw94X20TW2k=; Message-ID: <7f89a925-6c4e-7840-041b-2e0816ed7b71@xen.org> Date: Fri, 7 Jul 2023 12:16:46 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v2 3/3] [FUTURE] xen/arm: enable vPCI for domUs Content-Language: en-US To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Cc: Stewart Hildebrand , xen-devel@lists.xenproject.org, Stefano Stabellini , Bertrand Marquis , Volodymyr Babchuk , Oleksandr Tyshchenko , Artem Mygaiev References: <20230707014754.51333-1-stewart.hildebrand@amd.com> <20230707014754.51333-4-stewart.hildebrand@amd.com> <04c05db8-1e15-f2c1-ebc1-0563d442a808@xen.org> From: Julien Grall In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 07/07/2023 11:47, Roger Pau Monné wrote: > On Fri, Jul 07, 2023 at 11:33:14AM +0100, Julien Grall wrote: >> Hi, >> >> On 07/07/2023 11:06, Roger Pau Monné wrote: >>> On Fri, Jul 07, 2023 at 10:00:51AM +0100, Julien Grall wrote: >>>> On 07/07/2023 02:47, Stewart Hildebrand wrote: >>>>> Note that CONFIG_HAS_VPCI_GUEST_SUPPORT is not currently used in the upstream >>>>> code base. It will be used by the vPCI series [1]. This patch is intended to be >>>>> merged as part of the vPCI series. >>>>> >>>>> v1->v2: >>>>> * new patch >>>>> --- >>>>> xen/arch/arm/Kconfig | 1 + >>>>> xen/arch/arm/include/asm/domain.h | 2 +- >>>>> 2 files changed, 2 insertions(+), 1 deletion(-) >>>>> >>>>> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig >>>>> index 4e0cc421ad48..75dfa2f5a82d 100644 >>>>> --- a/xen/arch/arm/Kconfig >>>>> +++ b/xen/arch/arm/Kconfig >>>>> @@ -195,6 +195,7 @@ config PCI_PASSTHROUGH >>>>> depends on ARM_64 >>>>> select HAS_PCI >>>>> select HAS_VPCI >>>>> + select HAS_VPCI_GUEST_SUPPORT >>>>> default n >>>>> help >>>>> This option enables PCI device passthrough >>>>> diff --git a/xen/arch/arm/include/asm/domain.h b/xen/arch/arm/include/asm/domain.h >>>>> index 1a13965a26b8..6e016b00bae1 100644 >>>>> --- a/xen/arch/arm/include/asm/domain.h >>>>> +++ b/xen/arch/arm/include/asm/domain.h >>>>> @@ -298,7 +298,7 @@ static inline void arch_vcpu_block(struct vcpu *v) {} >>>>> #define arch_vm_assist_valid_mask(d) (1UL << VMASST_TYPE_runstate_update_flag) >>>>> -#define has_vpci(d) ({ IS_ENABLED(CONFIG_HAS_VPCI) && is_hardware_domain(d); }) >>>>> +#define has_vpci(d) ({ (void)(d); IS_ENABLED(CONFIG_HAS_VPCI); }) >>>> >>>> As I mentioned in the previous patch, wouldn't this enable vPCI >>>> unconditionally for all the domain? Shouldn't this be instead an optional >>>> feature which would be selected by the toolstack? >>> >>> I do think so, at least on x86 we signal whether vPCI should be >>> enabled for a domain using xen_arch_domainconfig at domain creation. >>> >>> Ideally we would like to do this on a per-device basis for domUs, so >>> we should consider adding a new flag to xen_domctl_assign_device in >>> order to signal whether the assigned device should use vPCI. >> >> I am a bit confused with this paragraph. If the device is not using vPCI, >> how will it be exposed to the domain? Are you planning to support both vPCI >> and PV PCI passthrough for a same domain? > > You could have an external device model handling it using the ioreq > interface, like we currently do passthrough for HVM guests. IMHO, if one decide to use QEMU for emulating the host bridge, then there is limited point to also ask Xen to emulate the hostbridge for some other device. So what would be the use case where you would want to be a per-device basis decision? Cheers, -- Julien Grall