[PATCH v8 21/23] Workaround for ERRATA_772415_SPR17

[Zhenzhong Duan <zhenzhong.duan@intel.com>]

On a system influenced by ERRATA_772415, IOMMU_HW_INFO_VTD_ERRATA_772415_SPR17
is repored by IOMMU_DEVICE_GET_HW_INFO. Due to this errata, even the readonly
range mapped on second stage page table could still be written.

Reference from 4th Gen Intel Xeon Processor Scalable Family Specification
Update, Errata Details, SPR17.
https://edc.intel.com/content/www/us/en/design/products-and-solutions/processors-and-chipsets/eagle-stream/sapphire-rapids-specification-update/

Also copied the SPR17 details from above link:
"Problem: When remapping hardware is configured by system software in
scalable mode as Nested (PGTT=011b) and with PWSNP field Set in the
PASID-table-entry, it may Set Accessed bit and Dirty bit (and Extended
Access bit if enabled) in first-stage page-table entries even when
second-stage mappings indicate that corresponding first-stage page-table
is Read-Only.

Implication: Due to this erratum, pages mapped as Read-only in second-stage
page-tables may be modified by remapping hardware Access/Dirty bit updates.

Workaround: None identified. System software enabling nested translations
for a VM should ensure that there are no read-only pages in the
corresponding second-stage mappings."

Introduce a helper vfio_device_get_host_iommu_quirk_bypass_ro to check if
readonly mappings should be bypassed.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
---
 include/hw/vfio/vfio-container.h |  1 +
 include/hw/vfio/vfio-device.h    |  3 +++
 hw/vfio/device.c                 | 14 ++++++++++++++
 hw/vfio/iommufd.c                |  9 ++++++++-
 hw/vfio/listener.c               |  6 ++++--
 5 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/include/hw/vfio/vfio-container.h b/include/hw/vfio/vfio-container.h
index 9f6e8cedfc..a7d5c5ed67 100644
--- a/include/hw/vfio/vfio-container.h
+++ b/include/hw/vfio/vfio-container.h
@@ -52,6 +52,7 @@ struct VFIOContainer {
     QLIST_HEAD(, VFIODevice) device_list;
     GList *iova_ranges;
     NotifierWithReturn cpr_reboot_notifier;
+    bool bypass_ro;
 };
 
 #define TYPE_VFIO_IOMMU "vfio-iommu"
diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
index 48d00c7bc4..f6f3d0e378 100644
--- a/include/hw/vfio/vfio-device.h
+++ b/include/hw/vfio/vfio-device.h
@@ -268,6 +268,9 @@ void vfio_device_prepare(VFIODevice *vbasedev, VFIOContainer *bcontainer,
 void vfio_device_unprepare(VFIODevice *vbasedev);
 
 bool vfio_device_get_viommu_flags_want_nesting(VFIODevice *vbasedev);
+bool vfio_device_get_host_iommu_quirk_bypass_ro(VFIODevice *vbasedev,
+                                                uint32_t type, void *caps,
+                                                uint32_t size);
 
 int vfio_device_get_region_info(VFIODevice *vbasedev, int index,
                                 struct vfio_region_info **info);
diff --git a/hw/vfio/device.c b/hw/vfio/device.c
index 71eb069eb6..290011e154 100644
--- a/hw/vfio/device.c
+++ b/hw/vfio/device.c
@@ -533,6 +533,20 @@ bool vfio_device_get_viommu_flags_want_nesting(VFIODevice *vbasedev)
     return false;
 }
 
+bool vfio_device_get_host_iommu_quirk_bypass_ro(VFIODevice *vbasedev,
+                                                uint32_t type, void *caps,
+                                                uint32_t size)
+{
+    VFIOPCIDevice *vdev = vfio_pci_from_vfio_device(vbasedev);
+
+    if (vdev) {
+        return !!(pci_device_get_host_iommu_quirks(PCI_DEVICE(vdev), type,
+                                                   caps, size) &
+                  HOST_IOMMU_QUIRK_NESTING_PARENT_BYPASS_RO);
+    }
+    return false;
+}
+
 /*
  * Traditional ioctl() based io
  */
diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index 63f8442865..2a7b0d0c07 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -351,6 +351,7 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
     VFIOContainer *bcontainer = VFIO_IOMMU(container);
     uint32_t type, flags = 0;
     uint64_t hw_caps;
+    VendorCaps caps;
     VFIOIOASHwpt *hwpt;
     uint32_t hwpt_id;
     int ret;
@@ -396,7 +397,8 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
      * instead.
      */
     if (!iommufd_backend_get_device_info(vbasedev->iommufd, vbasedev->devid,
-                                         &type, NULL, 0, &hw_caps, errp)) {
+                                         &type, &caps, sizeof(caps), &hw_caps,
+                                         errp)) {
         return false;
     }
 
@@ -411,6 +413,11 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
      */
     if (vfio_device_get_viommu_flags_want_nesting(vbasedev)) {
         flags |= IOMMU_HWPT_ALLOC_NEST_PARENT;
+
+        if (vfio_device_get_host_iommu_quirk_bypass_ro(vbasedev, type,
+                                                       &caps, sizeof(caps))) {
+            bcontainer->bypass_ro = true;
+        }
     }
 
     if (cpr_is_incoming()) {
diff --git a/hw/vfio/listener.c b/hw/vfio/listener.c
index ca2377d860..090f935d30 100644
--- a/hw/vfio/listener.c
+++ b/hw/vfio/listener.c
@@ -502,7 +502,8 @@ void vfio_container_region_add(VFIOContainer *bcontainer,
     int ret;
     Error *err = NULL;
 
-    if (!vfio_listener_valid_section(section, false, "region_add")) {
+    if (!vfio_listener_valid_section(section, bcontainer->bypass_ro,
+                                     "region_add")) {
         return;
     }
 
@@ -668,7 +669,8 @@ static void vfio_listener_region_del(MemoryListener *listener,
     int ret;
     bool try_unmap = true;
 
-    if (!vfio_listener_valid_section(section, false, "region_del")) {
+    if (!vfio_listener_valid_section(section, bcontainer->bypass_ro,
+                                     "region_del")) {
         return;
     }
 
-- 
2.47.1