From: "Xu, Quan" <quan.xu@intel.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
Stefano Stabellini <sstabellini@kernel.org>,
"Wu, Feng" <feng.wu@intel.com>,
"dario.faggioli@citrix.com" <dario.faggioli@citrix.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
Julien Grall <julien.grall@arm.com>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Subject: Re: [Patch v6 04/11] IOMMU: propagate IOMMU Device-TLB flush error up to IOMMU mapping (top level ones)
Date: Tue, 7 Jun 2016 08:40:27 +0000 [thread overview]
Message-ID: <945CA011AD5F084CBEA3E851C0AB28894B8C6F1C@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <57569F9702000078000F2767@prv-mh.provo.novell.com>
On June 07, 2016 4:19 PM, Jan Beulich <JBeulich@suse.com> wrote:
> >>> On 07.06.16 at 09:51, <quan.xu@intel.com> wrote:
> > I still have one question. If I add __must_check annotation to
> > iommu_unmap_page().
> > How to fix this -- unmapping the previous IOMMU maps when IOMMU
> > mapping is failed..
> > e.g.,
> >
> > ept_set_entry()
> > {
> > ...
> > for ( i = 0; i < (1 << order); i++ )
> > {
> > rc = iommu_map_page(d, gfn + i, mfn_x(mfn) + i, iommu_flags);
> > if ( unlikely(rc) )
> > {
> > while ( i-- )
> > iommu_unmap_page(p2m->domain, gfn + i);
> >
> > break;
> > }
> > }
> > ...
> > }
> >
> >
> > If we leave it as is, it leads to compilation errors as __must_check
> > annotation. Also we return the first error, so we are no need to
> > cumulate the error of iommu_unmap_page().
> > That's also why I hesitated to add __must_check annotation to
> > iommu_unmap_page().
>
> Well, with there already being a message logged down the call tree in case of
> error, I think the return value should simply be latched into a local variable,
> and nothing really be done with it (which should satisfy the compiler afaict,
> but it may be that Coverity would grumble about such). We really don't want
> to omit the __must_check just because there are a few cases where the error
> is of no further relevance; the annotation gets put there to make sure we
> catch all (current and future) cases where errors must not be ignored.
>
Agreed. We really need to add __must_check annotation to iommu_map_page() / iommu_unmap_page().
Along with discussion of a local variable for _for()_ loop, I need to define this local variable into _while()_ loop:
e.g., as above case:
+while ( i-- )
+{
+ int iommu_ret = iommu_unmap_page(p2m->domain, gfn + i);
+
+ break;
+}
, right?
But I really like this way:
+ int iommu_ret;
+
+while ( i-- )
+{
+ iommu_ret = iommu_unmap_page(p2m->domain, gfn + i);
+
+ break;
+}
Quan
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next prev parent reply other threads:[~2016-06-07 8:40 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-31 13:57 [Patch v6 00/11] Check VT-d Device-TLB flush error Xu, Quan
2016-05-31 13:57 ` [Patch v6 01/11] IOMMU: handle IOMMU mapping and unmapping failures Xu, Quan
2016-06-01 9:52 ` Jan Beulich
2016-05-31 13:57 ` [Patch v6 02/11] IOMMU/MMU: enhance the call trees of IOMMU unmapping and mapping Xu, Quan
2016-06-01 10:05 ` Jan Beulich
2016-06-02 6:00 ` Xu, Quan
2016-06-02 9:13 ` Jan Beulich
2016-05-31 13:57 ` [Patch v6 03/11] IOMMU: propagate IOMMU Device-TLB flush error up to IOMMU unmapping (top level ones) Xu, Quan
2016-05-31 13:57 ` [Patch v6 04/11] IOMMU: propagate IOMMU Device-TLB flush error up to IOMMU mapping " Xu, Quan
2016-06-01 10:24 ` Jan Beulich
2016-06-02 7:25 ` Xu, Quan
2016-06-02 9:21 ` Jan Beulich
2016-06-02 12:43 ` Xu, Quan
2016-06-07 7:51 ` Xu, Quan
2016-06-07 8:19 ` Jan Beulich
2016-06-07 8:40 ` Xu, Quan [this message]
2016-06-07 10:11 ` Jan Beulich
2016-05-31 13:57 ` [Patch v6 05/11] IOMMU/MMU: propagate IOMMU Device-TLB flush error up to iommu_iotlb_flush{, _all} " Xu, Quan
2016-05-31 13:57 ` [Patch v6 06/11] propagate IOMMU Device-TLB flush error up to EPT update " Xu, Quan
2016-05-31 13:57 ` [Patch v6 07/11] IOMMU: propagate IOMMU Device-TLB flush error up to IOMMU suspending " Xu, Quan
2016-06-01 10:39 ` Jan Beulich
2016-06-02 2:58 ` Xu, Quan
2016-06-02 9:22 ` Jan Beulich
2016-05-31 13:57 ` [Patch v6 08/11] IOMMU: propagate IOMMU Device-TLB flush error (leaf ones) Xu, Quan
2016-05-31 13:57 ` [Patch v6 09/11] vt-d: fix the IOMMU flush issue Xu, Quan
2016-06-01 15:36 ` Jan Beulich
2016-06-02 2:50 ` Xu, Quan
2016-05-31 13:57 ` [Patch v6 10/11] vt-d: propagate the IOMMU Device-TLB flush error up to ME phantom functions Xu, Quan
2016-05-31 13:57 ` [Patch v6 11/11] vt-d: add __must_check annotation to IOMMU flush pointers and handlers Xu, Quan
2016-06-02 10:06 ` Jan Beulich
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