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From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Paul Durrant <paul@xen.org>, Wei Liu <wl@xen.org>
Subject: Re: [PATCH v4 13/21] IOMMU/x86: prefill newly allocate page tables
Date: Fri, 20 May 2022 14:22:19 +0200	[thread overview]
Message-ID: <YoeH+9eMU0ui68Mn@Air-de-Roger> (raw)
In-Reply-To: <7163fdba-c128-1226-e1cc-d210c5db06ad@suse.com>

On Fri, May 20, 2022 at 01:13:28PM +0200, Jan Beulich wrote:
> On 20.05.2022 13:11, Jan Beulich wrote:
> > On 20.05.2022 12:47, Roger Pau Monné wrote:
> >> On Thu, May 19, 2022 at 02:12:04PM +0200, Jan Beulich wrote:
> >>> On 06.05.2022 13:16, Roger Pau Monné wrote:
> >>>> On Mon, Apr 25, 2022 at 10:40:55AM +0200, Jan Beulich wrote:
> >>>>> --- a/xen/drivers/passthrough/amd/iommu_map.c
> >>>>> +++ b/xen/drivers/passthrough/amd/iommu_map.c
> >>>>> @@ -115,7 +115,19 @@ static void set_iommu_ptes_present(unsig
> >>>>>  
> >>>>>      while ( nr_ptes-- )
> >>>>>      {
> >>>>> -        set_iommu_pde_present(pde, next_mfn, 0, iw, ir);
> >>>>> +        ASSERT(!pde->next_level);
> >>>>> +        ASSERT(!pde->u);
> >>>>> +
> >>>>> +        if ( pde > table )
> >>>>> +            ASSERT(pde->ign0 == find_first_set_bit(pde - table));
> >>>>> +        else
> >>>>> +            ASSERT(pde->ign0 == PAGE_SHIFT - 3);
> >>>>
> >>>> I think PAGETABLE_ORDER would be clearer here.
> >>>
> >>> I disagree - PAGETABLE_ORDER is a CPU-side concept. It's not used anywhere
> >>> in IOMMU code afaics.
> >>
> >> Isn't PAGE_SHIFT also a CPU-side concept in the same way?  I'm not
> >> sure what's the rule for declaring that PAGE_SHIFT is fine to use in
> >> IOMMU code  but not PAGETABLE_ORDER.
> > 
> > Hmm, yes and no. But for consistency with other IOMMU code I may want
> > to switch to PAGE_SHIFT_4K.
> 
> Except that, with the plan to re-use pt_update_contig_markers() for CPU-
> side re-coalescing, there I'd prefer to stick to PAGE_SHIFT.

Then can PAGETABLE_ORDER be used instead of PAGE_SHIFT - 3?

IMO it makes the code quite easier to understand.

Thanks, Roger.


  reply	other threads:[~2022-05-20 12:22 UTC|newest]

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-25  8:29 [PATCH v4 00/21] IOMMU: superpage support when not sharing pagetables Jan Beulich
2022-04-25  8:30 ` [PATCH v4 01/21] AMD/IOMMU: correct potentially-UB shifts Jan Beulich
2022-04-27 13:08   ` Andrew Cooper
2022-04-27 13:57     ` Jan Beulich
2022-05-03 10:10   ` Roger Pau Monné
2022-05-03 14:34     ` Jan Beulich
2022-04-25  8:32 ` [PATCH v4 02/21] IOMMU: simplify unmap-on-error in iommu_map() Jan Beulich
2022-04-27 13:16   ` Andrew Cooper
2022-04-27 14:05     ` Jan Beulich
2022-05-03 10:25   ` Roger Pau Monné
2022-05-03 14:37     ` Jan Beulich
2022-05-03 16:22       ` Roger Pau Monné
2022-04-25  8:32 ` [PATCH v4 03/21] IOMMU: add order parameter to ->{,un}map_page() hooks Jan Beulich
2022-04-25  8:33 ` [PATCH v4 04/21] IOMMU: have iommu_{,un}map() split requests into largest possible chunks Jan Beulich
2022-05-03 12:37   ` Roger Pau Monné
2022-05-03 14:44     ` Jan Beulich
2022-05-04 10:20       ` Roger Pau Monné
2022-04-25  8:34 ` [PATCH v4 05/21] IOMMU/x86: restrict IO-APIC mappings for PV Dom0 Jan Beulich
2022-05-03 13:00   ` Roger Pau Monné
2022-05-03 14:50     ` Jan Beulich
2022-05-04  9:32       ` Jan Beulich
2022-05-04 10:30         ` Roger Pau Monné
2022-05-04 10:51           ` Jan Beulich
2022-05-04 12:01             ` Roger Pau Monné
2022-05-04 12:12               ` Jan Beulich
2022-05-04 13:00                 ` Roger Pau Monné
2022-05-04 13:19                   ` Jan Beulich
2022-05-04 13:46                     ` Roger Pau Monné
2022-05-04 13:55                       ` Jan Beulich
2022-05-04 15:22                         ` Roger Pau Monné
2022-04-25  8:34 ` [PATCH v4 06/21] IOMMU/x86: perform PV Dom0 mappings in batches Jan Beulich
2022-05-03 14:49   ` Roger Pau Monné
2022-05-04  9:46     ` Jan Beulich
2022-05-04 11:20       ` Roger Pau Monné
2022-05-04 12:27         ` Jan Beulich
2022-05-04 13:55           ` Roger Pau Monné
2022-05-04 14:26             ` Jan Beulich
2022-04-25  8:35 ` [PATCH v4 07/21] IOMMU/x86: support freeing of pagetables Jan Beulich
2022-05-03 16:20   ` Roger Pau Monné
2022-05-04 13:07     ` Jan Beulich
2022-05-04 15:06       ` Roger Pau Monné
2022-05-05  8:20         ` Jan Beulich
2022-05-05  9:57           ` Roger Pau Monné
2022-04-25  8:36 ` [PATCH v4 08/21] AMD/IOMMU: walk trees upon page fault Jan Beulich
2022-05-04 15:57   ` Roger Pau Monné
2022-04-25  8:37 ` [PATCH v4 09/21] AMD/IOMMU: return old PTE from {set,clear}_iommu_pte_present() Jan Beulich
2022-04-25  8:38 ` [PATCH v4 10/21] AMD/IOMMU: allow use of superpage mappings Jan Beulich
2022-05-05 13:19   ` Roger Pau Monné
2022-05-05 14:34     ` Jan Beulich
2022-05-05 15:26       ` Roger Pau Monné
2022-04-25  8:38 ` [PATCH v4 11/21] VT-d: " Jan Beulich
2022-05-05 16:20   ` Roger Pau Monné
2022-05-06  6:13     ` Jan Beulich
2022-04-25  8:40 ` [PATCH v4 12/21] IOMMU: fold flush-all hook into "flush one" Jan Beulich
2022-05-06  8:38   ` Roger Pau Monné
2022-05-06  9:59     ` Jan Beulich
2022-04-25  8:40 ` [PATCH v4 13/21] IOMMU/x86: prefill newly allocate page tables Jan Beulich
2022-05-06 11:16   ` Roger Pau Monné
2022-05-19 12:12     ` Jan Beulich
2022-05-20 10:47       ` Roger Pau Monné
2022-05-20 11:11         ` Jan Beulich
2022-05-20 11:13           ` Jan Beulich
2022-05-20 12:22             ` Roger Pau Monné [this message]
2022-05-20 12:36               ` Jan Beulich
2022-05-20 14:28                 ` Roger Pau Monné
2022-05-20 14:38                   ` Roger Pau Monné
2022-05-23  6:49                     ` Jan Beulich
2022-05-23  9:10                       ` Roger Pau Monné
2022-05-23 10:52                         ` Jan Beulich
2022-04-25  8:41 ` [PATCH v4 14/21] x86: introduce helper for recording degree of contiguity in " Jan Beulich
2022-05-06 13:25   ` Roger Pau Monné
2022-05-18 10:06     ` Jan Beulich
2022-05-20 10:22       ` Roger Pau Monné
2022-05-20 10:59         ` Jan Beulich
2022-05-20 11:27           ` Roger Pau Monné
2022-04-25  8:42 ` [PATCH v4 15/21] AMD/IOMMU: free all-empty " Jan Beulich
2022-05-10 13:30   ` Roger Pau Monné
2022-05-18 10:18     ` Jan Beulich
2022-04-25  8:42 ` [PATCH v4 16/21] VT-d: " Jan Beulich
2022-04-27  4:09   ` Tian, Kevin
2022-05-10 14:30   ` Roger Pau Monné
2022-05-18 10:26     ` Jan Beulich
2022-05-20  0:38       ` Tian, Kevin
2022-05-20 11:13       ` Roger Pau Monné
2022-05-27  7:40         ` Jan Beulich
2022-05-27  7:53           ` Jan Beulich
2022-05-27  9:21             ` Roger Pau Monné
2022-04-25  8:43 ` [PATCH v4 17/21] AMD/IOMMU: replace all-contiguous page tables by superpage mappings Jan Beulich
2022-05-10 15:31   ` Roger Pau Monné
2022-05-18 10:40     ` Jan Beulich
2022-05-20 10:35       ` Roger Pau Monné
2022-04-25  8:43 ` [PATCH v4 18/21] VT-d: " Jan Beulich
2022-05-11 11:08   ` Roger Pau Monné
2022-05-18 10:44     ` Jan Beulich
2022-05-20 10:38       ` Roger Pau Monné
2022-04-25  8:44 ` [PATCH v4 19/21] IOMMU/x86: add perf counters for page table splitting / coalescing Jan Beulich
2022-05-11 13:48   ` Roger Pau Monné
2022-05-18 11:39     ` Jan Beulich
2022-05-20 10:41       ` Roger Pau Monné
2022-04-25  8:44 ` [PATCH v4 20/21] VT-d: fold iommu_flush_iotlb{,_pages}() Jan Beulich
2022-04-27  4:12   ` Tian, Kevin
2022-05-11 13:50   ` Roger Pau Monné
2022-04-25  8:45 ` [PATCH v4 21/21] VT-d: fold dma_pte_clear_one() into its only caller Jan Beulich
2022-04-27  4:13   ` Tian, Kevin
2022-05-11 13:57   ` Roger Pau Monné
2022-05-18 12:50 ` [PATCH v4 00/21] IOMMU: superpage support when not sharing pagetables Jan Beulich

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