x86/vtd: introduce a PVH implementation of iommu_inclusive_mapping

On certain Intel systems, as far as I can tell almost all pre-Haswell ones,
trying to boot a PVH Dom0 will freeze the box completely, up to the point that
not even the watchdog works. The freeze happens exactly when enabling the DMA
remapping in the IOMMU, the last line seen is:

(XEN) [VT-D]iommu_enable_translation: iommu->reg = ffff82c00021b000

In order to workaround this (which seems to be a lack of proper RMRR entries,
plus the IOMMU being unable to generate faults and freezing the entire system)
add a PVH specific implementation of iommu_inclusive_mapping, that maps
non-RAM, non-unusable regions into Dom0 p2m. Note that care is taken to not map
device MMIO regions that Xen is emulating, like the local APIC or the IO APIC.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Cc: Kevin Tian <kevin.tian@intel.com>

diff --git a/xen/drivers/passthrough/vtd/extern.h b/xen/drivers/passthrough/vtd/extern.h
index fb7edfaef9d6503ce96819e659384562845febee..0eaf8956fffc8df4bed843126c381401b1520822 100644 (file)
--- a/xen/drivers/passthrough/vtd/extern.h
+++ b/xen/drivers/passthrough/vtd/extern.h
@@ -100,5 +100,6 @@ bool_t platform_supports_intremap(void);
 bool_t platform_supports_x2apic(void);
 
 void vtd_set_hwdom_mapping(struct domain *d);
+void vtd_set_pvh_hwdom_mapping(struct domain *d);
 
 #endif // _VTD_EXTERN_H_

diff --git a/xen/drivers/passthrough/vtd/iommu.c b/xen/drivers/passthrough/vtd/iommu.c
index daaed0abbdd06b6ba3d948ea103aadf02651e83c..8ed28defe213003a73a99e441608459536a9f787 100644 (file)
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1303,6 +1303,8 @@ static void __hwdom_init intel_iommu_hwdom_init(struct domain *d)
         /* Set up 1:1 page table for hardware domain. */
         vtd_set_hwdom_mapping(d);
     }
+    else if ( is_hvm_domain(d) )
+        vtd_set_pvh_hwdom_mapping(d);
 
     setup_hwdom_pci_devices(d, setup_hwdom_device);
     setup_hwdom_rmrr(d);

diff --git a/xen/drivers/passthrough/vtd/x86/vtd.c b/xen/drivers/passthrough/vtd/x86/vtd.c
index 88a60b330752591dcd2a7084086d7a76995d8478..79c9b0526f56674a8168708ca6c361d4732c75f7 100644 (file)
--- a/xen/drivers/passthrough/vtd/x86/vtd.c
+++ b/xen/drivers/passthrough/vtd/x86/vtd.c
@@ -21,10 +21,12 @@
 #include <xen/softirq.h>
 #include <xen/domain_page.h>
 #include <asm/paging.h>
+#include <xen/iocap.h>
 #include <xen/iommu.h>
 #include <xen/irq.h>
 #include <xen/numa.h>
 #include <asm/fixmap.h>
+#include <asm/p2m.h>
 #include <asm/setup.h>
 #include "../iommu.h"
 #include "../dmar.h"
@@ -159,3 +161,40 @@ void __hwdom_init vtd_set_hwdom_mapping(struct domain *d)
     }
 }
 
+void __hwdom_init vtd_set_pvh_hwdom_mapping(struct domain *d)
+{
+    unsigned long pfn;
+
+    BUG_ON(!is_hardware_domain(d));
+
+    if ( !iommu_inclusive_mapping )
+        return;
+
+    /* NB: the low 1MB is already mapped in pvh_setup_p2m. */
+    for ( pfn = PFN_DOWN(MB(1)); pfn < PFN_DOWN(GB(4)); pfn++ )
+    {
+        p2m_access_t a;
+        int rc;
+
+        if ( !(pfn & 0xfff) )
+            process_pending_softirqs();
+
+        /* Skip RAM, ACPI and unusable regions. */
+        if ( page_is_ram_type(pfn, RAM_TYPE_CONVENTIONAL) ||
+             page_is_ram_type(pfn, RAM_TYPE_UNUSABLE) ||
+             page_is_ram_type(pfn, RAM_TYPE_ACPI) ||
+             !iomem_access_permitted(d, pfn, pfn) )
+            continue;
+
+        ASSERT(!xen_in_range(pfn));
+
+        a = rangeset_contains_range(mmio_ro_ranges, pfn, pfn) ? p2m_access_r
+                                                              : p2m_access_rw;
+        rc = set_identity_p2m_entry(d, pfn, a, 0);
+        if ( rc )
+           printk(XENLOG_WARNING VTDPREFIX
+                  " d%d: IOMMU mapping failed pfn %#lx: %d\n",
+                  d->domain_id, pfn, rc);
+    }
+}
+