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

[Roger Pau Monne]

iommu_share_p2m_table should not prevent PVH guests from using a shared page
table. Change the condition to has_hvm_container_domain instead of
is_hvm_domain. This allows both PVH and HVM guests to use it. Remove the
asserts in iommu_set_pgd and amd_iommu_share_p2m, iommu_share_p2m_table
and p2m_alloc_table already do them.

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 Monné 
Cc: Suravee Suthikulpanit 
Cc: Aravind Gopalakrishnan 
Cc: Jan Beulich 
Cc: Yang Zhang 
Cc: Kevin Tian 
---
 xen/drivers/passthrough/amd/iommu_map.c | 2 --
 xen/drivers/passthrough/iommu.c | 2 +-
 xen/drivers/passthrough/vtd/iommu.c | 2 --
 xen/drivers/passthrough/x86/iommu.c | 2 +-
 4 files changed, 2 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..3e11d6b 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -332,7 +332,7 @@ void iommu_share_p2m_table(struct domain* d)
 {
 const struct iommu_ops *ops = iommu_get_ops();
 
-if ( iommu_enabled && is_hvm_domain(d) )
+if ( iommu_enabled && has_hvm_container_domain(d) )
 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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Re: [Xen-devel] [PATCH] xen/iommu: fix usage of shared EPT/IOMMU page tables on PVH guests

[Jan Beulich]

>>> On 27.02.15 at 11:10,  wrote:
> iommu_share_p2m_table should not prevent PVH guests from using a shared page
> table. Change the condition to has_hvm_container_domain instead of
> is_hvm_domain. This allows both PVH and HVM guests to use it. Remove the
> asserts in iommu_set_pgd and amd_iommu_share_p2m, iommu_share_p2m_table
> and p2m_alloc_table already do them.

This wording is confusing - it took me to got into p2m_alloc_table()
to see that one half of the assertion is being satisfied there an
the other in iommu_share_p2m_table(). While not asserting what
IOMMU code does is quite fine in IOMMU code (especially as closely
related as is the case here), the assertion regarding what P2M
code does (and what a future second caller of
iommu_share_p2m_table() might violate) should be kept, but
perhaps be moved into iommu_share_p2m_table() instead of
keeping it in vendor specific code.

Jan


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