Re: [Xen-devel] [PATCH v2] xen/iommu: fix usage of shared EPT/IOMMU page tables on PVH guests

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Roger Pau Monne [mailto:roger.pau@xxxxxxxxxx]
> Sent: Friday, February 27, 2015 7:34 PM
> 
> iommu_share_p2m_table should not prevent PVH guests from using a shared
> page
> table between the IOMMU and EPT. Clean the code by removing the asserts in
> the vendor specific implementations (amd_iommu_share_p2m,
> iommu_set_pgd),
> and moving the hap_enabled assert to the caller (iommu_share_p2m_table).
> 
> Also fix another incorrect usage of is_hvm_domain usage in
> arch_iommu_populate_page_table. This has not given problems so far
> because
> all the pages in PVH guests are of type PGT_writable_page.
> 
> Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> Cc: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@xxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Yang Zhang <yang.z.zhang@xxxxxxxxx>
> Cc: Kevin Tian <kevin.tian@xxxxxxxxx>

Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>

btw, does this patch fix your earlier iommu faults with PVH Dom0?

Thanks
Kevin

> ---
> Changes since v1:
>  - Reword commit message.
>  - Move the hap_enabled assert from vendor implementation to the generic
>    code.
>  - Remove the has_hvm_container_domain condition from
> iommu_share_p2m_table,
>    hap_enabled is more restrictive.
> ---
>  xen/drivers/passthrough/amd/iommu_map.c | 2 --
>  xen/drivers/passthrough/iommu.c         | 3 ++-
>  xen/drivers/passthrough/vtd/iommu.c     | 2 --
>  xen/drivers/passthrough/x86/iommu.c     | 2 +-
>  4 files changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/amd/iommu_map.c
> b/xen/drivers/passthrough/amd/iommu_map.c
> index a8c60ec..31dc05d 100644
> --- a/xen/drivers/passthrough/amd/iommu_map.c
> +++ b/xen/drivers/passthrough/amd/iommu_map.c
> @@ -785,8 +785,6 @@ void amd_iommu_share_p2m(struct domain *d)
>      struct page_info *p2m_table;
>      mfn_t pgd_mfn;
> 
> -    ASSERT( is_hvm_domain(d) && d->arch.hvm_domain.hap_enabled );
> -
>      if ( !iommu_use_hap_pt(d) )
>          return;
> 
> diff --git a/xen/drivers/passthrough/iommu.c
> b/xen/drivers/passthrough/iommu.c
> index cc12735..7fcbbb1 100644
> --- a/xen/drivers/passthrough/iommu.c
> +++ b/xen/drivers/passthrough/iommu.c
> @@ -332,7 +332,8 @@ void iommu_share_p2m_table(struct domain* d)
>  {
>      const struct iommu_ops *ops = iommu_get_ops();
> 
> -    if ( iommu_enabled && is_hvm_domain(d) )
> +    ASSERT( hap_enabled(d) );
> +    if ( iommu_enabled )
>          ops->share_p2m(d);
>  }
> 
> diff --git a/xen/drivers/passthrough/vtd/iommu.c
> b/xen/drivers/passthrough/vtd/iommu.c
> index 2e113d7..ff542cb 100644
> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -1788,8 +1788,6 @@ static void iommu_set_pgd(struct domain *d)
>      struct hvm_iommu *hd  = domain_hvm_iommu(d);
>      mfn_t pgd_mfn;
> 
> -    ASSERT( is_hvm_domain(d) && d->arch.hvm_domain.hap_enabled );
> -
>      if ( !iommu_use_hap_pt(d) )
>          return;
> 
> diff --git a/xen/drivers/passthrough/x86/iommu.c
> b/xen/drivers/passthrough/x86/iommu.c
> index 52d8948..9eb8d33 100644
> --- a/xen/drivers/passthrough/x86/iommu.c
> +++ b/xen/drivers/passthrough/x86/iommu.c
> @@ -56,7 +56,7 @@ int arch_iommu_populate_page_table(struct domain *d)
> 
>      while ( !rc && (page = page_list_remove_head(&d->page_list)) )
>      {
> -        if ( is_hvm_domain(d) ||
> +        if ( has_hvm_container_domain(d) ||
>              (page->u.inuse.type_info & PGT_type_mask) ==
> PGT_writable_page )
>          {
>              BUG_ON(SHARED_M2P(mfn_to_gmfn(d,
> page_to_mfn(page))));
> --
> 1.9.3 (Apple Git-50)

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