From: "Jan Beulich" <JBeulich@suse.com>
To: Quan Xu <quan.xu@intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>, Keir Fraser <keir@xen.org>,
AndrewCooper <andrew.cooper3@citrix.com>,
"dario.faggioli@citrix.com" <dario.faggioli@citrix.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
Feng Wu <feng.wu@intel.com>
Subject: Re: [PATCH v4 01/10] vt-d: fix the IOMMU flush issue
Date: Thu, 12 May 2016 02:53:02 -0600 [thread overview]
Message-ID: <5734608E02000078000EAD2B@prv-mh.provo.novell.com> (raw)
In-Reply-To: <945CA011AD5F084CBEA3E851C0AB28894B8AD4D2@SHSMSX101.ccr.corp.intel.com>
>>> On 12.05.16 at 09:50, <quan.xu@intel.com> wrote:
> On May 10, 2016 12:10 AM, Jan Beulich <JBeulich@suse.com> wrote:
>> >>> On 06.05.16 at 10:54, <quan.xu@intel.com> wrote:
>> > -static void intel_iommu_iotlb_flush(struct domain *d, unsigned long
>> > gfn, unsigned int page_count)
>> > +static void iommu_flush_iotlb_page(struct domain *d, unsigned long gfn,
>> > + unsigned int page_count)
>>
>> The new name suggests just one page. Please use e.g.
>> iommu_flush_iotlb_pages() instead.
>>
>
> Make sense.
>
>> > {
>> > - __intel_iommu_iotlb_flush(d, gfn, 1, page_count);
>> > + iommu_flush_iotlb(d, gfn, 1, page_count);
>> > }
>>
>> But of course the question is whether having this wrapper is useful in the first
>> place,
>
>
> This wrapper assumes the 'dma_old_pte_present' is '1', but in another caller
> intel_iommu_map_page(), i.e.
>
>
> intel_iommu_map_page()
> {
> ...
> if ( !this_cpu(iommu_dont_flush_iotlb) )
> iommu_flush_iotlb(d, gfn, dma_pte_present(old), 1);
> ...
> }
>
>
> the 'dma_old_pte_present' is not sure.
I'm sorry, but you're looking at this backwards: I suggested to
remove the wrapper, not to move any check into iommu_flush_iotlb().
Removing the wrapper simply means to move the passing of the
hard coded 1 into the current callers of that wrapper.
>> > @@ -1391,13 +1399,19 @@ int domain_context_mapping_one(
>> > spin_unlock(&iommu->lock);
>> >
>> > /* Context entry was previously non-present (with domid 0). */
>> > - if ( iommu_flush_context_device(iommu, 0, (((u16)bus) << 8) | devfn,
>> > - DMA_CCMD_MASK_NOBIT, 1) )
>> > - iommu_flush_write_buffer(iommu);
>> > - else
>> > + rc = iommu_flush_context_device(iommu, 0, (((u16)bus) << 8) | devfn,
>> > + DMA_CCMD_MASK_NOBIT, 1);
>> > +
>> > + if ( !rc )
>> > {
>> > int flush_dev_iotlb = find_ats_dev_drhd(iommu) ? 1 : 0;
>> > - iommu_flush_iotlb_dsi(iommu, 0, 1, flush_dev_iotlb);
>> > + rc = iommu_flush_iotlb_dsi(iommu, 0, 1, flush_dev_iotlb);
>>
>> Please take the opportunity and add the missing blank line (between
>> declaration(s) and statement(s) in cases like this.
>>
>> > + }
>> > +
>> > + if ( rc > 0 )
>>
>> Can iommu_flush_context_device() return a positive value? If so, the logic is
>> now likely wrong. If not (which is what I assume) I'd like to suggest adding a
>> respective ASSERT() (even if only to document the fact). Or alternatively this
>> if() could move into the immediately preceding one.
>
> Check it again. iommu_flush_context_device() can return a positive value.
> [...]
> Could you tell me why the logic is now likely wrong? I will fix it first.
With
rc = iommu_flush_context_device(iommu, 0, (((u16)bus) << 8) | devfn,
DMA_CCMD_MASK_NOBIT, 1);
if ( !rc )
{
int flush_dev_iotlb = find_ats_dev_drhd(iommu) ? 1 : 0;
rc = iommu_flush_iotlb_dsi(iommu, 0, 1, flush_dev_iotlb);
}
if ( rc > 0 )
{
iommu_flush_write_buffer(iommu);
rc = 0;
}
it seems pretty clear that you won't call iommu_flush_iotlb_dsi() if
iommu_flush_context_device() returned 1, which doesn't look like
what is wanted at the first glance. But I may be wrong, hence the
"likely" in my earlier reply.
Jan
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next prev parent reply other threads:[~2016-05-12 8:53 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-06 8:54 [PATCH v4 00/10] Check VT-d Device-TLB flush error Quan Xu
2016-05-06 8:54 ` [PATCH v4 01/10] vt-d: fix the IOMMU flush issue Quan Xu
2016-05-09 16:09 ` Jan Beulich
2016-05-12 7:50 ` Xu, Quan
2016-05-12 8:53 ` Jan Beulich [this message]
2016-05-12 13:29 ` Xu, Quan
2016-05-12 13:37 ` Jan Beulich
2016-05-12 13:43 ` Xu, Quan
2016-05-06 8:54 ` [PATCH v4 02/10] IOMMU: handle IOMMU mapping and unmapping failures Quan Xu
2016-05-09 16:13 ` Jan Beulich
2016-05-10 3:41 ` Xu, Quan
2016-05-10 6:53 ` Jan Beulich
2016-05-10 7:53 ` Xu, Quan
2016-05-10 8:02 ` Jan Beulich
2016-05-10 8:20 ` Xu, Quan
2016-05-10 8:26 ` Jan Beulich
2016-05-12 14:28 ` Xu, Quan
2016-05-12 15:06 ` Jan Beulich
2016-05-13 8:04 ` Xu, Quan
2016-05-13 9:08 ` Jan Beulich
2016-05-13 9:20 ` Xu, Quan
2016-05-06 8:54 ` [PATCH v4 03/10] IOMMU/MMU: enhance the call trees of IOMMU unmapping and mapping Quan Xu
2016-05-10 8:44 ` Jan Beulich
2016-05-10 14:45 ` George Dunlap
2016-05-10 14:59 ` George Dunlap
2016-05-11 2:26 ` Xu, Quan
2016-05-11 8:45 ` George Dunlap
2016-05-11 8:58 ` Xu, Quan
2016-05-10 15:02 ` Jan Beulich
2016-05-11 2:29 ` Xu, Quan
2016-05-11 3:39 ` Xu, Quan
2016-05-11 7:02 ` Jan Beulich
2016-05-06 8:54 ` [PATCH v4 04/10] vt-d: propagate IOMMU Device-TLB flush error up to IOMMU unmapping Quan Xu
2016-05-10 8:50 ` Jan Beulich
2016-05-11 3:49 ` Xu, Quan
2016-05-06 8:54 ` [PATCH v4 05/10] vt-d: propagate IOMMU Device-TLB flush error up to IOMMU mapping Quan Xu
2016-05-06 8:54 ` [PATCH v4 06/10] IOMMU/MMU: propagate IOMMU Device-TLB flush error up to iommu_iotlb_flush{, _all} (top level ones) Quan Xu
2016-05-10 9:04 ` Jan Beulich
2016-05-11 5:52 ` Xu, Quan
2016-05-06 8:54 ` [PATCH v4 07/10] IOMMU: propagate IOMMU Device-TLB flush error up to iommu_iotlb_flush{, _all} (leaf ones) Quan Xu
2016-05-10 9:06 ` Jan Beulich
2016-05-11 6:47 ` Xu, Quan
2016-05-11 7:06 ` Jan Beulich
2016-05-11 7:12 ` Xu, Quan
2016-05-11 7:16 ` Jan Beulich
2016-05-11 7:20 ` Xu, Quan
2016-05-11 7:37 ` Jan Beulich
2016-05-06 8:54 ` [PATCH v4 08/10] vt-d/ept: propagate IOMMU Device-TLB flush error up to EPT update Quan Xu
2016-05-10 9:09 ` Jan Beulich
2016-05-10 14:58 ` George Dunlap
2016-05-10 15:04 ` Jan Beulich
2016-05-11 7:25 ` Xu, Quan
2016-05-06 8:54 ` [PATCH v4 09/10] IOMMU: propagate IOMMU Device-TLB flush error up to IOMMU suspending Quan Xu
2016-05-10 9:24 ` Jan Beulich
2016-05-13 3:39 ` Xu, Quan
2016-05-13 6:16 ` Jan Beulich
2016-05-13 6:27 ` Xu, Quan
2016-05-06 8:54 ` [PATCH v4 10/10] vt-d: propagate error up to ME phantom function mapping and unmapping Quan Xu
2016-05-10 9:29 ` Jan Beulich
2016-05-11 8:35 ` Xu, Quan
2016-05-11 9:07 ` Jan Beulich
2016-05-12 5:16 ` Xu, Quan
2016-05-12 8:44 ` Jan Beulich
2016-05-12 9:02 ` Xu, Quan
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