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Tue, 20 Oct 2020 17:17:21 +0000 (UTC) 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: MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=6XRVWEq9OP5/+7TDqIxD74K72OTW4DwG6dXwruk5jZI=; b=ED+EJ9pAuuNXMRv4ZNOnrp3DHe X+v2jtzE8zMpMZGywk+QiBFsqozS9syrNdAmk28dtZNleL8cTkE7pT+0mOAOLFGpZS2oM3vijDHNc g724OsazygwjrDaoEg2XZC+Oe26pkFDTGFGh5mO6o0f/AWLTx/Uyb0GYvGXQCNosKz/M=; Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kUvG6-0000K1-Sr; Tue, 20 Oct 2020 17:17:14 +0000 Received: from 54-240-197-236.amazon.com ([54.240.197.236] helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1kUvG6-0007JD-Le; Tue, 20 Oct 2020 17:17:14 +0000 Subject: Re: [PATCH 2/5] iommu / domctl: introduce XEN_DOMCTL_iommu_ctl To: paul@xen.org, xen-devel@lists.xenproject.org Cc: 'Paul Durrant' , 'Daniel De Graaf' , 'Ian Jackson' , 'Wei Liu' , 'Andrew Cooper' , 'George Dunlap' , 'Jan Beulich' , 'Stefano Stabellini' References: <20201005094905.2929-1-paul@xen.org> <20201005094905.2929-3-paul@xen.org> <97648df3-dcce-cd19-9074-6ca63d94b518@xen.org> <002a01d6a5e8$c36bb5a0$4a4320e0$@xen.org> From: Julien Grall Message-ID: Date: Tue, 20 Oct 2020 18:17:12 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.3.3 MIME-Version: 1.0 In-Reply-To: <002a01d6a5e8$c36bb5a0$4a4320e0$@xen.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Hi Paul, On 19/10/2020 08:23, Paul Durrant wrote: >> -----Original Message----- >> From: Julien Grall >> Sent: 16 October 2020 16:47 >> To: Paul Durrant ; xen-devel@lists.xenproject.org >> Cc: Paul Durrant ; Daniel De Graaf ; Ian Jackson >> ; Wei Liu ; Andrew Cooper ; George Dunlap >> ; Jan Beulich ; Stefano Stabellini >> >> Subject: Re: [PATCH 2/5] iommu / domctl: introduce XEN_DOMCTL_iommu_ctl >> >> Hi Paul, >> >> On 05/10/2020 10:49, Paul Durrant wrote: >>> diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h >>> index 791f0a2592..75e855625a 100644 >>> --- a/xen/include/public/domctl.h >>> +++ b/xen/include/public/domctl.h >>> @@ -1130,6 +1130,18 @@ struct xen_domctl_vuart_op { >>> */ >>> }; >>> >>> +/* >>> + * XEN_DOMCTL_iommu_ctl >>> + * >>> + * Control of VM IOMMU settings >>> + */ >>> + >>> +#define XEN_DOMCTL_IOMMU_INVALID 0 >> >> I can't find any user of XEN_DOMCTL_IOMMU_INVALID. What's the purpose >> for it? >> > > It's just a placeholder. I think it's generally safer that a zero opcode value is invalid. Thanks for the explanation. I first thought the goal would to somehow invalidate the IOMMU :). Anyway, it might be worth adding /* Reserved - should never be used */ on top. Cheers, -- Julien Grall