[Xen-changelog] [xen stable-4.6] PVH Dom0 RMRR IOMMU mapping regression fix

[patchbot@xxxxxxx]

commit db9375dbde236c1e3c4a63724b3460b41e5a5037
Author:     Elena Ufimtseva <elena.ufimtseva@xxxxxxxxxx>
AuthorDate: Tue Sep 29 15:15:14 2015 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Sep 29 15:15:14 2015 +0200

    PVH Dom0 RMRR IOMMU mapping regression fix
    
    This patch addresses a regression introduced by commit
    5ae03990c120a7b3067a52d9784c9aa72c0705a6 in new set_identity_p2m_entry.
    RMRRs are not being mapped in IOMMU for PVH Dom0. This causes pages faults 
and
    some long 'hang-like' delays during Dom0 PVH boot and device assignments.
    
    During construct_dom0, in PVH path p2m is being constructed and identity 
mapped
    in IOMMU. The p2m type is p2m_mmio_direct and p2m access p2m_rwx.
    New code used to map RMRRs invoked from rmrr_identity_mapping
    checks if p2m entry exists with same type and access and if yes, skips iommu
    mapping. Since there are p2m entries for pvh dom0 iomem, RMRRs are not being
    mapped in IOMMU.
    
    As was mentioned in the earlier discussion, the PVH Dom0 construction code
    should be modified to properly map RMRR regions in IOMMU. Since change will 
be
    too invasive, this solution is a temporary fix at this time before better
    solution is in. Also as Jan mentioned, there is no need in having 'x' 
permissions
    for p2m entry of a mmio region, thus changed here.
    
    Signed-off-by: Elena Ufimtseva <elena.ufimtseva@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Release-acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    master commit: 0e9e09880d5f65ccb178d6c5785305ecf5715bba
    master date: 2015-09-29 13:53:31 +0200
---
 xen/arch/x86/domain_build.c |    4 ++--
 xen/arch/x86/mm/p2m.c       |    9 +++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index 18cf6aa..bca6fe7 100644
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -432,9 +432,9 @@ static __init void pvh_add_mem_mapping(struct domain *d, 
unsigned long gfn,
         }
 
         if ( rangeset_contains_singleton(mmio_ro_ranges, mfn + i) )
-            a = p2m_access_rx;
+            a = p2m_access_r;
         else
-            a = p2m_access_rwx;
+            a = p2m_access_rw;
 
         if ( (rc = set_mmio_p2m_entry(d, gfn + i, _mfn(mfn + i), a)) )
             panic("pvh_add_mem_mapping: gfn:%lx mfn:%lx i:%ld rc:%d\n",
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 6b4a35b..c6b883d 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -971,7 +971,16 @@ int set_identity_p2m_entry(struct domain *d, unsigned long 
gfn,
         ret = p2m_set_entry(p2m, gfn, _mfn(gfn), PAGE_ORDER_4K,
                             p2m_mmio_direct, p2ma);
     else if ( mfn_x(mfn) == gfn && p2mt == p2m_mmio_direct && a == p2ma )
+    {
         ret = 0;
+        /*
+         * PVH fixme: during Dom0 PVH construction, p2m entries are being set
+         * but iomem regions are not mapped with IOMMU. This makes sure that
+         * RMRRs are correctly mapped with IOMMU.
+         */
+        if ( is_hardware_domain(d) && !iommu_use_hap_pt(d) )
+            ret = iommu_map_page(d, gfn, gfn, IOMMUF_readable|IOMMUF_writable);
+    }
     else
     {
         if ( flag & XEN_DOMCTL_DEV_RDM_RELAXED )
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.6

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