From: Paul Durrant <xadimgnik@gmail.com>
To: "'Jan Beulich'" <jbeulich@suse.com>
Cc: "'Julien Grall'" <julien@xen.org>,
<xen-devel@lists.xenproject.org>,
"'Paul Durrant'" <pdurrant@amazon.com>,
"'Daniel De Graaf'" <dgdegra@tycho.nsa.gov>,
"'Ian Jackson'" <iwj@xenproject.org>, "'Wei Liu'" <wl@xen.org>,
"'Andrew Cooper'" <andrew.cooper3@citrix.com>,
"'George Dunlap'" <george.dunlap@citrix.com>,
"'Stefano Stabellini'" <sstabellini@kernel.org>
Subject: RE: [PATCH 2/5] iommu / domctl: introduce XEN_DOMCTL_iommu_ctl
Date: Mon, 19 Oct 2020 08:32:57 +0100 [thread overview]
Message-ID: <002d01d6a5ea$112d9aa0$3388cfe0$@xen.org> (raw)
In-Reply-To: <7c4a0cda-5fff-c9ae-2fc1-4256aec5f694@suse.com>
> -----Original Message-----
> From: Jan Beulich <jbeulich@suse.com>
> Sent: 19 October 2020 08:30
> To: paul@xen.org
> Cc: 'Julien Grall' <julien@xen.org>; xen-devel@lists.xenproject.org; 'Paul Durrant'
> <pdurrant@amazon.com>; 'Daniel De Graaf' <dgdegra@tycho.nsa.gov>; 'Ian Jackson' <iwj@xenproject.org>;
> 'Wei Liu' <wl@xen.org>; 'Andrew Cooper' <andrew.cooper3@citrix.com>; 'George Dunlap'
> <george.dunlap@citrix.com>; 'Stefano Stabellini' <sstabellini@kernel.org>
> Subject: Re: [PATCH 2/5] iommu / domctl: introduce XEN_DOMCTL_iommu_ctl
>
> On 19.10.2020 09:23, Paul Durrant wrote:
> >> From: Julien Grall <julien@xen.org>
> >> Sent: 16 October 2020 16:47
> >>
> >> 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.
>
> But does this then need a #define? Starting valid command from 1
> ought to be sufficient?
>
Seems harmless enough, and it also seemed the best way since to reserve 0 since this patch doesn't actually introduce any ops. As it has caused so much controversy though, I'll remove it.
Paul
> Jan
next prev parent reply other threads:[~2020-10-19 7:33 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-05 9:49 [PATCH 0/5] iommu page-table memory pool Paul Durrant
2020-10-05 9:49 ` [PATCH 1/5] libxl: remove separate calculation of IOMMU memory overhead Paul Durrant
2020-10-08 13:07 ` Wei Liu
2020-10-05 9:49 ` [PATCH 2/5] iommu / domctl: introduce XEN_DOMCTL_iommu_ctl Paul Durrant
2020-10-16 15:47 ` Julien Grall
2020-10-19 7:23 ` Paul Durrant
2020-10-19 7:29 ` Jan Beulich
2020-10-19 7:32 ` Paul Durrant [this message]
2020-10-20 17:17 ` Julien Grall
2020-10-05 9:49 ` [PATCH 3/5] libxl / iommu / domctl: introduce XEN_DOMCTL_IOMMU_SET_ALLOCATION Paul Durrant
2020-10-08 13:08 ` Wei Liu
2020-10-16 15:54 ` Julien Grall
2020-10-19 7:30 ` Paul Durrant
2020-10-30 16:45 ` Jan Beulich
2020-10-05 9:49 ` [PATCH 4/5] iommu: set 'hap_pt_share' and 'need_sync' flags earlier in iommu_domain_init() Paul Durrant
2020-10-16 16:07 ` Julien Grall
2020-10-30 16:11 ` Jan Beulich
2020-10-05 9:49 ` [PATCH 5/5] x86 / iommu: create a dedicated pool of page-table pages Paul Durrant
2020-10-30 16:43 ` Jan Beulich
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