On Thu, 2008-07-10 at 17:30 +0800, Yang, Sheng wrote:
> On Thursday 10 July 2008 17:14:42 Ben-Ami Yassour wrote:
> > From: Kay, Allen M <[EMAIL PROTECTED]>
> >
> > This patch includes the functions to support VT-d for passthrough
> > devices.
> >
> > [Ben: fixed memory pinning]
> >
> > Signed-off-by: Kay, Allen M <[EMAIL PROTECTED]>
> > Signed-off-by: Weidong Han <[EMAIL PROTECTED]>
> > Signed-off-by: Ben-Ami Yassour <[EMAIL PROTECTED]>
> > ---
> >  arch/x86/kvm/Makefile      |    2 +-
> >  arch/x86/kvm/vtd.c         |  176
> > ++++++++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/x86.c    
> >     |   10 +++
> >  include/asm-x86/kvm_host.h |    1 +
> >  include/linux/kvm_host.h   |    6 ++
> >  virt/kvm/kvm_main.c        |    6 ++
> >  6 files changed, 200 insertions(+), 1 deletions(-)
> >  create mode 100644 arch/x86/kvm/vtd.c
> >
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index 531d635..dc67d90 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -41,6 +41,7 @@
> >  #include <linux/pagemap.h>
> >  #include <linux/mman.h>
> >  #include <linux/swap.h>
> > +#include <linux/intel-iommu.h>
> >
> >  #include <asm/processor.h>
> >  #include <asm/io.h>
> > @@ -422,6 +423,11 @@ int __kvm_set_memory_region(struct kvm *kvm,
> >     }
> >
> >     kvm_free_physmem_slot(&old, &new);
> > +
> > +   /* map the pages in iommu page table */
> > +   if (intel_iommu_found())
> > +           kvm_iommu_map_pages(kvm, base_gfn, npages);
> > +
> 
> I don't understand why we need this along with  
> kvm_iommu_map_memslots(). This works during the memory setup, and in 
> kvm_iommu_map_guest() we do it again with the overlapped memory 
> region?
> 
> I think even if we need pin all pages, we still just need do it 
> once...

We map the entire guest memory on initialization by going over all the
existing memory slots.
If a new slot is created later then we need to map it as well, this is
the call that you see here.

Regards,
Ben


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