Re: [PATCH 06/11] kvm: Change kvm_iommu_map_pages to map large pages

Marcelo Tosatti
2010-01-28T22:24:55Z

On Thu, Jan 28, 2010 at 12:37:57PM +0100, Joerg Roedel wrote:
> This patch changes the implementation of of
> kvm_iommu_map_pages to map the pages with the host page size
> into the io virtual address space.
>
> Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
> ---
> virt/kvm/iommu.c | 106 ++++++++++++++++++++++++++++++++++++++++++-----------
> 1 files changed, 84 insertions(+), 22 deletions(-)
>
> diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
> index 65a5143..92a434d 100644
> --- a/virt/kvm/iommu.c
> +++ b/virt/kvm/iommu.c
> @@ -32,12 +32,27 @@ static int kvm_iommu_unmap_memslots(struct kvm *kvm);
> static void kvm_iommu_put_pages(struct kvm *kvm,
> gfn_t base_gfn, unsigned long npages);
>
> +static pfn_t kvm_pin_pages(struct kvm *kvm, struct kvm_memory_slot *slot,
> + gfn_t gfn, unsigned long size)
> +{
> + gfn_t end_gfn;
> + pfn_t pfn;
> +
> + pfn = gfn_to_pfn_memslot(kvm, slot, gfn);

If gfn_to_pfn_memslot returns pfn of bad_page, you might create a
large iommu translation for it?

> + /* Map into IO address space */
> + r = iommu_map(domain, gfn_to_gpa(gfn), pfn_to_hpa(pfn),
> + get_order(page_size), flags);
> +
> + gfn += page_size >> PAGE_SHIFT;

Should increase gfn after checking for failure, otherwise wrong
npages is passed to kvm_iommu_put_pages.

>
> - pfn = gfn_to_pfn_memslot(kvm, slot, gfn);
> - r = iommu_map_range(domain,
> - gfn_to_gpa(gfn),
> - pfn_to_hpa(pfn),
> - PAGE_SIZE, flags);
> if (r) {
> printk(KERN_ERR "kvm_iommu_map_address:"
> "iommu failed to map pfn=%lx\n", pfn);
> goto unmap_pages;
> }
> - gfn++;
> +
> }
> +
> return 0;
>
> unmap_pages:
> - kvm_iommu_put_pages(kvm, slot->base_gfn, i);
> + kvm_iommu_put_pages(kvm, slot->base_gfn, gfn);
> return r;
> }