[Xen-devel] [PATCH v4 1/4] xen: make logdirty and iommu mutually exclusive

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Prevent the usage of global logdirty if the domain is using the IOMMU,
and also prevent passthrough of devices if logdirty is enabled.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
---
Changes since v2:
 - Check for global logdirty enable in paging_log_dirty_enable instead
   of doing it in shadow/ept code.
 - Use the newly introduced global_logdirty flag to check if the
   domain has global logdirty enabled.
---
 xen/arch/x86/mm/paging.c      |    9 +++++++++
 xen/drivers/passthrough/pci.c |    3 ++-
 2 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/xen/arch/x86/mm/paging.c b/xen/arch/x86/mm/paging.c
index 9e9a11b..32764ba 100644
--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -168,6 +168,15 @@ int paging_log_dirty_enable(struct domain *d, bool_t 
log_global)
 {
     int ret;
 
+    if ( need_iommu(d) && log_global )
+    {
+        /*
+         * Refuse to turn on global log-dirty mode
+         * if the domain is using the IOMMU.
+         */
+        return -EINVAL;
+    }
+
     if ( paging_mode_log_dirty(d) )
         return -EINVAL;
 
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index b7f6e8a..43c1a81 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -1233,7 +1233,8 @@ static int assign_device(struct domain *d, u16 seg, u8 
bus, u8 devfn)
      * enabled for this domain */
     if ( unlikely(!need_iommu(d) &&
             (d->arch.hvm_domain.mem_sharing_enabled ||
-             d->mem_event->paging.ring_page)) )
+             d->mem_event->paging.ring_page ||
+             p2m_get_hostp2m(d)->global_logdirty)) )
         return -EXDEV;
 
     if ( !spin_trylock(&pcidevs_lock) )
-- 
1.7.7.5 (Apple Git-26)


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