Re: [PATCH] KVM: PCIPT: VT-d support

["Yang, Sheng" <sheng.yang@intel.com>]

On Thursday 10 July 2008 17:14:42 Ben-Ami Yassour wrote:
> From: Kay, Allen M <allen.m.kay@intel.com>
>
> This patch includes the functions to support VT-d for passthrough
> devices.
>
> [Ben: fixed memory pinning]
>
> Signed-off-by: Kay, Allen M <allen.m.kay@intel.com>
> Signed-off-by: Weidong Han <weidong.han@intel.com>
> Signed-off-by: Ben-Ami Yassour <benami@il.ibm.com>
> ---
>  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...

--
Thanks
Yang, Sheng