Mailing List Archive

commit 83432adeb82122e392a3bfc2a8818d25ca9e69ed
Author: Jan Beulich <jbeulich@suse.com>
AuthorDate: Fri Oct 23 10:06:53 2020 +0200
Commit: Jan Beulich <jbeulich@suse.com>
CommitDate: Fri Oct 23 10:06:53 2020 +0200

IOMMU/EPT: avoid double flushing in shared page table case

While the flush coalescing optimization has been helping the non-shared
case, it has actually lead to double flushes in the shared case (which
ought to be the more common one nowadays at least): Once from
*_set_entry() and a second time up the call tree from wherever the
overriding flag gets played with. In alignment with XSA-346 suppress
flushing in this case.

Similarly avoid excessive setting of IOMMU_FLUSHF_added on the batched
flushes: "idx" hasn't been added a new mapping for.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
---
xen/arch/x86/mm/p2m-ept.c | 2 +-
xen/common/memory.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 12cf38f6eb..476458b1e0 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -842,7 +842,7 @@ out:
if ( rc == 0 && p2m_is_hostp2m(p2m) &&
need_modify_vtd_table )
{
- if ( iommu_use_hap_pt(d) )
+ if ( iommu_use_hap_pt(d) && !this_cpu(iommu_dont_flush_iotlb) )
rc = iommu_iotlb_flush(d, _dfn(gfn), 1ul << order,
(iommu_flags ? IOMMU_FLUSHF_added : 0) |
(vtd_pte_present ? IOMMU_FLUSHF_modified
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 7075e233aa..df85b550a1 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -870,7 +870,7 @@ int xenmem_add_to_physmap(struct domain *d, struct xen_add_to_physmap *xatp,
this_cpu(iommu_dont_flush_iotlb) = 0;

ret = iommu_iotlb_flush(d, _dfn(xatp->idx - done), done,
- IOMMU_FLUSHF_added | IOMMU_FLUSHF_modified);
+ IOMMU_FLUSHF_modified);
if ( unlikely(ret) && rc >= 0 )
rc = ret;

--
generated by git-patchbot for /home/xen/git/xen.git#master