[Xen-devel] Re: [PATCH 0/6] IOMMU, vtd and iotlb flush rework (v7)

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.11.11 at 18:40, Jean Guyader <jean.guyader@xxxxxxxxxxxxx> wrote:
> In one of my previous email I detailed a bug I was seeing when passing
> through a Intel GPU on a guest that has more that 4G or RAM.
> 
> Allen suggested that I go for the Plan B but after a discussion with Tim
> we agreed that Plan B was way to disruptive in term of code change.
> 
> This patch series implements Plan A.
> 
> http://xen.1045712.n5.nabble.com/VTD-Intel-iommu-IOTLB-flush-really-slow-td4 
> 952866.html
> 
> Changes between v6 and v7:
>         - xenmem_add_to_physmap_once can't take a pointer on xatp because
>           it modifies .idx and .gpfn.

This is not an excuse for passing a structure by value. Despite the
structure not being huge, I still consider this bad style.

Jan

>         - Cancel hypercall continuation in the compat layer if the 
> copy_to_guest
>           failed.
> 
> Changes between v5 and v6:
>        - Rework the patch queue to make it more readable.
>        - Modify xatp in place in xenmem_add_to_physmap
>        - Only check for preemption if we are not at the last iteration
>        - Copy xatp guest handler back to the guest only in case of 
> continuation
>        - Add continuation only when dealing with the new xenmem space
>          (XENMAPSPACE_gmfn_range).
> 
> Changes between v4 and v5:
>        - Fix hypercall continuation for add_to_physmap in compat mode.
> 
> Changes between v3 and v4:
>        - Move the loop for gmfn_range from arch_memory_op to 
> xenmem_add_to_physmap.
>        - Add a comment to comment to explain the purpose of 
> iommu_dont_flush_iotlb.
> 
> Changes between v2 and v3:
>        - Check for the presence iotlb_flush_all callback before calling it.
> 
> Changes between v1 and v2:
>        - Move size in struct xen_add_to_physmap in padding between .domid 
> and .space.
>        - Store iommu_dont_flush per cpu
>        - Change the code in hvmloader to relocate by batch of 64K, .size is 
> now 16 bits.
> 
> Jean Guyader (6):
>   vtd: Refactor iotlb flush code
>   iommu: Introduce iommu_flush and iommu_flush_all.
>   add_to_physmap: Move the code for XENMEM_add_to_physmap
>   mm: New XENMEM space, XENMAPSPACE_gmfn_range
>   hvmloader: Change memory relocation loop when overlap with PCI hole
>   Introduce per cpu flag (iommu_dont_flush_iotlb) to avoid unnecessary
>     iotlb flush
> 
>  tools/firmware/hvmloader/pci.c      |   20 ++-
>  xen/arch/x86/mm.c                   |  231 
> ++++++++++++++++++++++-------------
>  xen/arch/x86/x86_64/compat/mm.c     |   14 ++
>  xen/drivers/passthrough/iommu.c     |   25 ++++
>  xen/drivers/passthrough/vtd/iommu.c |  100 +++++++++-------
>  xen/include/public/memory.h         |    4 +
>  xen/include/xen/iommu.h             |   17 +++
>  7 files changed, 279 insertions(+), 132 deletions(-)




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