From: "Xu, Quan" <quan.xu@intel.com>
To: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>, Keir Fraser <keir@xen.org>,
"Nakajima, Jun" <jun.nakajima@intel.com>,
Liu Jinsong <jinsong.liu@alibaba-inc.com>,
Dario Faggioli <dario.faggioli@citrix.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
Jan Beulich <jbeulich@suse.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
"Wu, Feng" <feng.wu@intel.com>
Subject: Re: [PATCH 1/2] IOMMU/MMU: Adjust top level functions for VT-d Device-TLB flush error.
Date: Fri, 18 Mar 2016 03:19:05 +0000 [thread overview]
Message-ID: <945CA011AD5F084CBEA3E851C0AB28894B867105@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <CAFLBxZZ9=vbcKQJS=NvjdNf+1uvOzSDOkAg8FNLDv3CC2ygXfw@mail.gmail.com>
On March 17, 2016 8:34pm, George Dunlap <George.Dunlap@eu.citrix.com> wrote:
> On Thu, Mar 17, 2016 at 12:30 PM, George Dunlap
> <George.Dunlap@eu.citrix.com> wrote:
> > On Thu, Mar 17, 2016 at 6:54 AM, Quan Xu <quan.xu@intel.com> wrote:
> >> diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index
> >> c997b53..526548e 100644
> >> --- a/xen/arch/x86/mm.c
> >> +++ b/xen/arch/x86/mm.c
> >> @@ -2467,7 +2467,7 @@ static int __get_page_type(struct page_info
> *page, unsigned long type,
> >> int preemptible) {
> >> unsigned long nx, x, y = page->u.inuse.type_info;
> >> - int rc = 0;
> >> + int rc = 0, ret = 0;
> >>
> >> ASSERT(!(type & ~(PGT_type_mask | PGT_pae_xen_l2)));
> >>
> >> @@ -2578,11 +2578,11 @@ static int __get_page_type(struct page_info
> *page, unsigned long type,
> >> if ( d && is_pv_domain(d) && unlikely(need_iommu(d)) )
> >> {
> >> if ( (x & PGT_type_mask) == PGT_writable_page )
> >> - iommu_unmap_page(d, mfn_to_gmfn(d,
> page_to_mfn(page)));
> >> + ret = iommu_unmap_page(d, mfn_to_gmfn(d,
> page_to_mfn(page)));
> >> else if ( type == PGT_writable_page )
> >> - iommu_map_page(d, mfn_to_gmfn(d,
> page_to_mfn(page)),
> >> - page_to_mfn(page),
> >> -
> IOMMUF_readable|IOMMUF_writable);
> >> + ret = iommu_map_page(d, mfn_to_gmfn(d,
> page_to_mfn(page)),
> >> + page_to_mfn(page),
> >> +
> IOMMUF_readable|IOMMUF_writable);
> >> }
> >> }
> >>
> >> @@ -2599,6 +2599,9 @@ static int __get_page_type(struct page_info
> *page, unsigned long type,
> >> if ( (x & PGT_partial) && !(nx & PGT_partial) )
> >> put_page(page);
> >>
> >> + if ( !rc )
> >> + rc = ret;
> >> +
> >
> > What's this about? If the iommu_[un]map_page() operation times out,
> > we still go through with calling alloc_page_type(); and if
> > alloc_page_type() fails we return its failure value, but if it
> > succeeds, we return the error from iommu_[un]map_page()?
> >
> >> return rc;
> >> }
> >>
> >> diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
> >> index 3cb6868..f9bcce7 100644
> >> --- a/xen/arch/x86/mm/p2m-ept.c
> >> +++ b/xen/arch/x86/mm/p2m-ept.c
> >> @@ -830,7 +830,15 @@ out:
> >> {
> >> if ( iommu_flags )
> >> for ( i = 0; i < (1 << order); i++ )
> >> - iommu_map_page(d, gfn + i, mfn_x(mfn) + i,
> iommu_flags);
> >> + {
> >> + rc = iommu_map_page(d, gfn + i, mfn_x(mfn) + i,
> iommu_flags);
> >> + if ( rc )
> >> + {
> >> + while ( i-- > 0 )
> >> + iommu_unmap_page(d, gfn + i);
> >
> > This won't unmap gfn+0 (since it will break out when i == 0 without
> > calling unmap).
>
> Oh, no it won't, because the decrement is postfix.
>
> For us mere mortals, I'd appreciate a comment here like this:
>
> /* Postfix operator means we will call unmap with i == 0 */
>
Agreed.
For these 2 points, to summarize:
- adding "unlikely()" to the if() condition, e.g. if ( unlikely(rc) )
- adding a comment:
/* Postfix operator means we will call unmap with i == 0 */
Right?
Quan
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next prev parent reply other threads:[~2016-03-18 3:19 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-17 6:54 [PATCH 0/2] Check VT-d Device-TLB flush error Quan Xu
2016-03-17 6:54 ` [PATCH 1/2] IOMMU/MMU: Adjust top level functions for " Quan Xu
2016-03-17 7:32 ` Tian, Kevin
2016-03-17 7:58 ` Jan Beulich
2016-03-17 8:00 ` Tian, Kevin
2016-03-17 12:30 ` George Dunlap
2016-03-17 12:33 ` George Dunlap
2016-03-18 3:19 ` Xu, Quan [this message]
2016-03-18 8:09 ` Jan Beulich
2016-03-24 6:45 ` Xu, Quan
2016-03-18 7:54 ` Xu, Quan
2016-03-18 8:19 ` Jan Beulich
2016-03-18 9:09 ` Xu, Quan
2016-03-18 9:29 ` Jan Beulich
2016-03-18 9:38 ` Dario Faggioli
2016-03-18 9:48 ` Jan Beulich
2016-03-21 6:18 ` Tian, Kevin
2016-03-21 12:22 ` Jan Beulich
2016-03-24 9:02 ` Xu, Quan
2016-03-24 9:58 ` Jan Beulich
2016-03-24 14:12 ` Xu, Quan
2016-03-24 14:37 ` Jan Beulich
2016-03-17 17:14 ` Jan Beulich
2016-03-28 3:33 ` Xu, Quan
2016-03-29 7:20 ` Jan Beulich
2016-03-30 2:28 ` Xu, Quan
2016-03-30 2:35 ` Xu, Quan
2016-03-30 8:05 ` Jan Beulich
2016-03-17 6:54 ` [PATCH 2/2] IOMMU/MMU: Adjust low " Quan Xu
2016-03-17 7:37 ` Tian, Kevin
2016-03-18 2:30 ` Xu, Quan
2016-03-18 8:06 ` Jan Beulich
2016-03-21 5:01 ` Tian, Kevin
2016-03-17 15:31 ` George Dunlap
2016-03-18 6:57 ` Xu, Quan
2016-03-18 10:20 ` Jan Beulich
2016-03-25 9:27 ` Xu, Quan
2016-03-29 7:36 ` Jan Beulich
2016-04-11 3:09 ` Xu, Quan
2016-04-11 3:27 ` Xu, Quan
2016-04-11 16:34 ` Jan Beulich
2016-04-12 1:09 ` Xu, Quan
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