Re: [PATCH 3/3] vdpa: Check for iova range at mappings changes

On Tue, Oct 05, 2021 at 11:58:12AM +0200, Eugenio Perez Martin wrote:

On Tue, Oct 5, 2021 at 10:14 AM Michael S. Tsirkin [off-list ref] wrote:

quoted

On Tue, Oct 05, 2021 at 10:01:31AM +0200, Eugenio Pérez wrote:

quoted

Check vdpa device range before updating memory regions so we don't add
any outside of it, and report the invalid change if any.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 include/hw/virtio/vhost-vdpa.h |  2 +
 hw/virtio/vhost-vdpa.c         | 68 ++++++++++++++++++++++++++--------
 hw/virtio/trace-events         |  1 +
 3 files changed, 55 insertions(+), 16 deletions(-)

diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
index a8963da2d9..c288cf7ecb 100644
--- a/include/hw/virtio/vhost-vdpa.h
+++ b/include/hw/virtio/vhost-vdpa.h

@@ -13,6 +13,7 @@
 #define HW_VIRTIO_VHOST_VDPA_H

 #include "hw/virtio/virtio.h"
+#include "standard-headers/linux/vhost_types.h"

 typedef struct VhostVDPAHostNotifier {
     MemoryRegion mr;

@@ -24,6 +25,7 @@ typedef struct vhost_vdpa {
     uint32_t msg_type;
     bool iotlb_batch_begin_sent;
     MemoryListener listener;
+    struct vhost_vdpa_iova_range iova_range;
     struct vhost_dev *dev;
     VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX];
 } VhostVDPA;

diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index a1de6c7c9c..26d0258723 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c

@@ -33,20 +33,34 @@ static Int128 vhost_vdpa_section_end(const MemoryRegionSection *section)
     return llend;
 }

-static bool vhost_vdpa_listener_skipped_section(MemoryRegionSection *section)
-{
-    return (!memory_region_is_ram(section->mr) &&
-            !memory_region_is_iommu(section->mr)) ||
-            memory_region_is_protected(section->mr) ||
-           /* vhost-vDPA doesn't allow MMIO to be mapped  */
-            memory_region_is_ram_device(section->mr) ||
-           /*
-            * Sizing an enabled 64-bit BAR can cause spurious mappings to
-            * addresses in the upper part of the 64-bit address space.  These
-            * are never accessed by the CPU and beyond the address width of
-            * some IOMMU hardware.  TODO: VDPA should tell us the IOMMU width.
-            */
-           section->offset_within_address_space & (1ULL << 63);
+static bool vhost_vdpa_listener_skipped_section(MemoryRegionSection *section,
+                                                uint64_t iova_min,
+                                                uint64_t iova_max)
+{
+    Int128 llend;
+    bool r = (!memory_region_is_ram(section->mr) &&
+              !memory_region_is_iommu(section->mr)) ||
+              memory_region_is_protected(section->mr) ||
+              /* vhost-vDPA doesn't allow MMIO to be mapped  */
+              memory_region_is_ram_device(section->mr);
+    if (r) {
+        return true;
+    }
+
+    if (section->offset_within_address_space < iova_min) {
+        error_report("RAM section out of device range (min=%lu, addr=%lu)",
+                     iova_min, section->offset_within_address_space);
+        return true;
+    }
+
+    llend = vhost_vdpa_section_end(section);
+    if (int128_make64(llend) > iova_max) {

I am puzzled by this.
You are taking a Int128, converting to u64, converting
back to Int128, and comparing to u64.
Head spins. What is all this back and forth trying to achieve?

You are totally right, this series was extracted from a longer one
where I didn't use vhost_vdpa_section_end, but raw addresses. Then I
applied int128_make64 to the wrong variable, too fast.

To be sure we are on the same page, to do:

if (int128_ge(int128_make64(iova), llend)) {
    // error message
    return;
}

The same way as vhost_vdpa_listener_region_{add,del} would be ok?

Thanks!

should be ok, yea

quoted

quoted

+        error_report("RAM section out of device range (max=%lu, end addr=%lu)",
+                     iova_max, (uint64_t)int128_make64(llend));
+        return true;
+    }
+
+    return false;
 }

 static int vhost_vdpa_dma_map(struct vhost_vdpa *v, hwaddr iova, hwaddr size,

@@ -158,7 +172,8 @@ static void vhost_vdpa_listener_region_add(MemoryListener *listener,
     void *vaddr;
     int ret;

-    if (vhost_vdpa_listener_skipped_section(section)) {
+    if (vhost_vdpa_listener_skipped_section(section, v->iova_range.first,
+                                            v->iova_range.last)) {
         return;
     }

@@ -216,7 +231,8 @@ static void vhost_vdpa_listener_region_del(MemoryListener *listener,
     Int128 llend, llsize;
     int ret;

-    if (vhost_vdpa_listener_skipped_section(section)) {
+    if (vhost_vdpa_listener_skipped_section(section, v->iova_range.first,
+                                            v->iova_range.last)) {
         return;
     }

@@ -284,9 +300,24 @@ static void vhost_vdpa_add_status(struct vhost_dev *dev, uint8_t status)
     vhost_vdpa_call(dev, VHOST_VDPA_SET_STATUS, &s);
 }

+static int vhost_vdpa_get_iova_range(struct vhost_vdpa *v)
+{
+    int ret;
+
+    ret = vhost_vdpa_call(v->dev, VHOST_VDPA_GET_IOVA_RANGE, &v->iova_range);
+    if (ret != 0) {
+        return ret;
+    }
+
+    trace_vhost_vdpa_get_iova_range(v->dev, v->iova_range.first,
+                                    v->iova_range.last);
+    return ret;
+}
+
 static int vhost_vdpa_init(struct vhost_dev *dev, void *opaque, Error **errp)
 {
     struct vhost_vdpa *v;
+    int r;
     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_VDPA);
     trace_vhost_vdpa_init(dev, opaque);

@@ -296,6 +327,11 @@ static int vhost_vdpa_init(struct vhost_dev *dev, void *opaque, Error **errp)
     v->listener = vhost_vdpa_memory_listener;
     v->msg_type = VHOST_IOTLB_MSG_V2;

+    r = vhost_vdpa_get_iova_range(v);
+    if (unlikely(!r)) {
+        return r;
+    }
+
     vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE |
                                VIRTIO_CONFIG_S_DRIVER);

diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
index 8ed19e9d0c..650e521e35 100644
--- a/hw/virtio/trace-events
+++ b/hw/virtio/trace-events

@@ -52,6 +52,7 @@ vhost_vdpa_set_vring_call(void *dev, unsigned int index, int fd) "dev: %p index:
 vhost_vdpa_get_features(void *dev, uint64_t features) "dev: %p features: 0x%"PRIx64
 vhost_vdpa_set_owner(void *dev) "dev: %p"
 vhost_vdpa_vq_get_addr(void *dev, void *vq, uint64_t desc_user_addr, uint64_t avail_user_addr, uint64_t used_user_addr) "dev: %p vq: %p desc_user_addr: 0x%"PRIx64" avail_user_addr: 0x%"PRIx64" used_user_addr: 0x%"PRIx64
+vhost_vdpa_get_iova_range(void *dev, uint64_t first, uint64_t last) "dev: %p first: 0x%"PRIx64" last: 0x%"PRIx64

 # virtio.c
 virtqueue_alloc_element(void *elem, size_t sz, unsigned in_num, unsigned out_num) "elem %p size %zd in_num %u out_num %u"
--

2.27.0

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