[RFC v4 0/2] memory: Delete assertion in memory_region_unregister_iommu_notifier

[RFC v4 0/2] memory: Delete assertion in memory_region_unregister_iommu_notifier

[Eugenio Pérez]

I am able to hit this assertion when a Red Hat 7 guest virtio_net device
raises an "Invalidation" of all the TLB entries. This happens in the
guest's startup if 'intel_iommu=on' argument is passed to the guest
kernel and right IOMMU/ATS devices are declared in qemu's command line.

Command line:
/home/qemu/x86_64-softmmu/qemu-system-x86_64 -name \
guest=rhel7-test,debug-threads=on -machine \
pc-q35-5.1,accel=kvm,usb=off,dump-guest-core=off,kernel_irqchip=split \
-cpu \
Broadwell,vme=on,ss=on,vmx=on,f16c=on,rdrand=on,hypervisor=on,arat=on,tsc-adjust=on,umip=on,arch-capabilities=on,xsaveopt=on,pdpe1gb=on,abm=on,skip-l1dfl-vmentry=on,rtm=on,hle=on \
-m 8096 -realtime mlock=off -smp 2,sockets=2,cores=1,threads=1 -uuid \
d022ecbf-679e-4755-87ce-eb87fc5bbc5d -display none -no-user-config \
-nodefaults -rtc base=utc,driftfix=slew -global \
kvm-pit.lost_tick_policy=delay -no-hpet -no-shutdown -global \
ICH9-LPC.disable_s3=1 -global ICH9-LPC.disable_s4=1 -boot strict=on \
-device intel-iommu,intremap=on,device-iotlb=on -device \
pcie-root-port,port=0x8,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,addr=0x1 \
-device \
pcie-root-port,port=0x9,chassis=2,id=pci.2,bus=pcie.0,addr=0x1.0x1 \
-device \
pcie-root-port,port=0xa,chassis=3,id=pci.3,bus=pcie.0,addr=0x1.0x2 \
-device \
pcie-root-port,port=0xb,chassis=4,id=pci.4,bus=pcie.0,addr=0x1.0x3 \
-device \
pcie-root-port,port=0xc,chassis=5,id=pci.5,bus=pcie.0,addr=0x1.0x4 \
-device \
pcie-root-port,port=0xd,chassis=6,id=pci.6,bus=pcie.0,addr=0x1.0x5 \
-device \
pcie-root-port,port=0xe,chassis=7,id=pci.7,bus=pcie.0,addr=0x1.0x6 \
-device qemu-xhci,p2=15,p3=15,id=usb,bus=pci.2,addr=0x0 -device \
virtio-serial-pci,id=virtio-serial0,bus=pci.3,addr=0x0 -drive \
file=/home/virtio-test2.qcow2,format=qcow2,if=none,id=drive-virtio-disk0 \
-device \
virtio-blk-pci,scsi=off,bus=pci.4,addr=0x0,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 \
-netdev tap,id=hostnet0,vhost=on,vhostforce=on -device \
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:0d:1d:f2,bus=pci.1,addr=0x0,iommu_platform=on,ats=on \
-device virtio-balloon-pci,id=balloon0,bus=pci.5,addr=0x0 -object \
rng-random,id=objrng0,filename=/dev/urandom -device \
virtio-rng-pci,rng=objrng0,id=rng0,bus=pci.6,addr=0x0 -s -msg \
timestamp=on

#0  0x00007ffff521370f in raise () at /lib64/libc.so.6
#1  0x00007ffff51fdb25 in abort () at /lib64/libc.so.6
#2  0x00007ffff51fd9f9 in _nl_load_domain.cold.0 () at /lib64/libc.so.6
#3  0x00007ffff520bcc6 in .annobin_assert.c_end () at /lib64/libc.so.6
#4  0x0000555555888171 in memory_region_notify_one
(notifier=0x7ffde0487fa8, entry=0x7ffde5dfe200) at
/home/qemu/memory.c:1918
#5  0x0000555555888247 in memory_region_notify_iommu
(iommu_mr=0x555556f6c0b0, iommu_idx=0, entry=...) at
/home/qemu/memory.c:1941
#6  0x0000555555951c8d in vtd_process_device_iotlb_desc
(s=0x555557609000, inv_desc=0x7ffde5dfe2d0)
    at /home/qemu/hw/i386/intel_iommu.c:2468
#7  0x0000555555951e6a in vtd_process_inv_desc (s=0x555557609000) at
/home/qemu/hw/i386/intel_iommu.c:2531
#8  0x0000555555951fa5 in vtd_fetch_inv_desc (s=0x555557609000) at
/home/qemu/hw/i386/intel_iommu.c:2563
#9  0x00005555559520e5 in vtd_handle_iqt_write (s=0x555557609000) at
/home/qemu/hw/i386/intel_iommu.c:2590
#10 0x0000555555952b45 in vtd_mem_write (opaque=0x555557609000,
addr=136, val=2688, size=4) at /home/qemu/hw/i386/intel_iommu.c:2837
#11 0x0000555555883e17 in memory_region_write_accessor
    (mr=0x555557609330, addr=136, value=0x7ffde5dfe478, size=4,
shift=0, mask=4294967295, attrs=...) at /home/qemu/memory.c:483
#12 0x000055555588401d in access_with_adjusted_size
    (addr=136, value=0x7ffde5dfe478, size=4, access_size_min=4,
access_size_max=8, access_fn=
    0x555555883d38 <memory_region_write_accessor>, mr=0x555557609330,
attrs=...) at /home/qemu/memory.c:544
#13 0x0000555555886f37 in memory_region_dispatch_write
(mr=0x555557609330, addr=136, data=2688, op=MO_32, attrs=...)
    at /home/qemu/memory.c:1476
#14 0x0000555555827a03 in flatview_write_continue
    (fv=0x7ffdd8503150, addr=4275634312, attrs=...,
ptr=0x7ffff7ff0028, len=4, addr1=136, l=4, mr=0x555557609330) at
/home/qemu/exec.c:3146
#15 0x0000555555827b48 in flatview_write (fv=0x7ffdd8503150,
addr=4275634312, attrs=..., buf=0x7ffff7ff0028, len=4)
    at /home/qemu/exec.c:3186
#16 0x0000555555827e9d in address_space_write
    (as=0x5555567ca640 <address_space_memory>, addr=4275634312,
attrs=..., buf=0x7ffff7ff0028, len=4) at /home/qemu/exec.c:3277
#17 0x0000555555827f0a in address_space_rw
    (as=0x5555567ca640 <address_space_memory>, addr=4275634312,
attrs=..., buf=0x7ffff7ff0028, len=4, is_write=true)
    at /home/qemu/exec.c:3287
#18 0x000055555589b633 in kvm_cpu_exec (cpu=0x555556b65640) at
/home/qemu/accel/kvm/kvm-all.c:2511
#19 0x0000555555876ba8 in qemu_kvm_cpu_thread_fn (arg=0x555556b65640)
at /home/qemu/cpus.c:1284
#20 0x0000555555dafff1 in qemu_thread_start (args=0x555556b8c3b0) at
util/qemu-thread-posix.c:521
#21 0x00007ffff55a62de in start_thread () at /lib64/libpthread.so.0
#22 0x00007ffff52d7e83 in clone () at /lib64/libc.so.6

(gdb) frame 4
#4  0x0000555555888171 in memory_region_notify_one
(notifier=0x7ffde0487fa8, entry=0x7ffde5dfe200) at
/home/qemu/memory.c:1918
1918        assert(entry->iova >= notifier->start && entry_end <=
notifier->end);
(gdb) p *entry
$1 = {target_as = 0x555556f6c050, iova = 0, translated_addr = 0,
addr_mask = 18446744073709551615, perm = IOMMU_NONE}
--

Tested with vhost-net, with a linux bridge to forward packets.
Forwarding with vhostuser interfaces + dpdk-testpmd io forwarding mode seems
broken also in v5.1.0-rc3.

v4: Rename IOMMU_NOTIFIER_IOTLB -> IOMMU_NOTIFIER_DEVIOTLB.
    Make vhost-net notifier just IOMMU_NOTIFIER_DEVIOTLB, not
    IOMMU_NOTIFIER_UNMAP

v3: Skip the assertion in case notifier is a IOTLB one, since they can manage
    arbitrary ranges. Using a flag in the notifier for now, as Peter suggested.

v2: Actually delete assertion instead of just commenting out using C99

Eugenio Pérez (2):
  memory: Rename memory_region_notify_one to
    memory_region_notify_one_iommu
  memory: Skip bad range assertion if notifier is DEVIOTLB type

 hw/arm/smmu-common.c  |  2 +-
 hw/arm/smmuv3.c       |  2 +-
 hw/i386/intel_iommu.c |  4 ++--
 hw/virtio/vhost.c     |  2 +-
 include/exec/memory.h |  8 +++++---
 softmmu/memory.c      | 21 ++++++++++++++++-----
 6 files changed, 26 insertions(+), 13 deletions(-)

-- 
2.18.1

[RFC v4 1/2] memory: Rename memory_region_notify_one to memory_region_notify_one_iommu

[Eugenio Pérez]

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/arm/smmu-common.c  | 2 +-
 hw/arm/smmuv3.c       | 2 +-
 hw/i386/intel_iommu.c | 4 ++--
 include/exec/memory.h | 6 +++---
 softmmu/memory.c      | 6 +++---
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/hw/arm/smmu-common.c b/hw/arm/smmu-common.c
index e13a5f4a7c..3d7fc87ff8 100644
--- a/hw/arm/smmu-common.c
+++ b/hw/arm/smmu-common.c
@@ -396,7 +396,7 @@ static void smmu_unmap_notifier_range(IOMMUNotifier *n)
     entry.perm = IOMMU_NONE;
     entry.addr_mask = n->end - n->start;
 
-    memory_region_notify_one(n, &entry);
+    memory_region_notify_one_iommu(n, &entry);
 }
 
 /* Unmap all notifiers attached to @mr */
diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
index 57a79df55b..cc3d4de319 100644
--- a/hw/arm/smmuv3.c
+++ b/hw/arm/smmuv3.c
@@ -838,7 +838,7 @@ static void smmuv3_notify_iova(IOMMUMemoryRegion *mr,
     entry.addr_mask = (1 << tt->granule_sz) - 1;
     entry.perm = IOMMU_NONE;
 
-    memory_region_notify_one(n, &entry);
+    memory_region_notify_one_iommu(n, &entry);
 }
 
 /* invalidate an asid/iova tuple in all mr's */
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 5284bb68b6..d68e91c729 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -3498,7 +3498,7 @@ static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n)
         /* This field is meaningless for unmap */
         entry.translated_addr = 0;
 
-        memory_region_notify_one(n, &entry);
+        memory_region_notify_one_iommu(n, &entry);
 
         start += mask;
         remain -= mask;
@@ -3536,7 +3536,7 @@ static void vtd_address_space_refresh_all(IntelIOMMUState *s)
 
 static int vtd_replay_hook(IOMMUTLBEntry *entry, void *private)
 {
-    memory_region_notify_one((IOMMUNotifier *)private, entry);
+    memory_region_notify_one_iommu((IOMMUNotifier *)private, entry);
     return 0;
 }
 
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 307e527835..ed99a80f17 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -226,7 +226,7 @@ enum IOMMUMemoryRegionAttr {
  * The IOMMU implementation must use the IOMMU notifier infrastructure
  * to report whenever mappings are changed, by calling
  * memory_region_notify_iommu() (or, if necessary, by calling
- * memory_region_notify_one() for each registered notifier).
+ * memory_region_notify_one_iommu() for each registered notifier).
  *
  * Conceptually an IOMMU provides a mapping from input address
  * to an output TLB entry. If the IOMMU is aware of memory transaction
@@ -1274,7 +1274,7 @@ void memory_region_notify_iommu(IOMMUMemoryRegion *iommu_mr,
                                 IOMMUTLBEntry entry);
 
 /**
- * memory_region_notify_one: notify a change in an IOMMU translation
+ * memory_region_notify_one_iommu: notify a change in an IOMMU translation
  *                           entry to a single notifier
  *
  * This works just like memory_region_notify_iommu(), but it only
@@ -1285,7 +1285,7 @@ void memory_region_notify_iommu(IOMMUMemoryRegion *iommu_mr,
  *         replaces all old entries for the same virtual I/O address range.
  *         Deleted entries have .@perm == 0.
  */
-void memory_region_notify_one(IOMMUNotifier *notifier,
+void memory_region_notify_one_iommu(IOMMUNotifier *notifier,
                               IOMMUTLBEntry *entry);
 
 /**
diff --git a/softmmu/memory.c b/softmmu/memory.c
index af25987518..0043791361 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -1890,8 +1890,8 @@ void memory_region_unregister_iommu_notifier(MemoryRegion *mr,
     memory_region_update_iommu_notify_flags(iommu_mr, NULL);
 }
 
-void memory_region_notify_one(IOMMUNotifier *notifier,
-                              IOMMUTLBEntry *entry)
+void memory_region_notify_one_iommu(IOMMUNotifier *notifier,
+                                    IOMMUTLBEntry *entry)
 {
     IOMMUNotifierFlag request_flags;
     hwaddr entry_end = entry->iova + entry->addr_mask;
@@ -1927,7 +1927,7 @@ void memory_region_notify_iommu(IOMMUMemoryRegion *iommu_mr,
 
     IOMMU_NOTIFIER_FOREACH(iommu_notifier, iommu_mr) {
         if (iommu_notifier->iommu_idx == iommu_idx) {
-            memory_region_notify_one(iommu_notifier, &entry);
+            memory_region_notify_one_iommu(iommu_notifier, &entry);
         }
     }
 }
-- 
2.18.1

[RFC v4 2/2] memory: Skip bad range assertion if notifier is DEVIOTLB type

[Eugenio Pérez]

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/virtio/vhost.c     |  2 +-
 include/exec/memory.h |  2 ++
 softmmu/memory.c      | 15 +++++++++++++--
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 1a1384e7a6..6ca168b47e 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -729,7 +729,7 @@ static void vhost_iommu_region_add(MemoryListener *listener,
     iommu_idx = memory_region_iommu_attrs_to_index(iommu_mr,
                                                    MEMTXATTRS_UNSPECIFIED);
     iommu_notifier_init(&iommu->n, vhost_iommu_unmap_notify,
-                        IOMMU_NOTIFIER_UNMAP,
+                        IOMMU_NOTIFIER_DEVIOTLB,
                         section->offset_within_region,
                         int128_get64(end),
                         iommu_idx);
diff --git a/include/exec/memory.h b/include/exec/memory.h
index ed99a80f17..74ab71543a 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -87,6 +87,8 @@ typedef enum {
     IOMMU_NOTIFIER_UNMAP = 0x1,
     /* Notify entry changes (newly created entries) */
     IOMMU_NOTIFIER_MAP = 0x2,
+    /* Notify changes on device IOTLB entries */
+    IOMMU_NOTIFIER_DEVIOTLB = 0x04,
 } IOMMUNotifierFlag;
 
 #define IOMMU_NOTIFIER_ALL (IOMMU_NOTIFIER_MAP | IOMMU_NOTIFIER_UNMAP)
diff --git a/softmmu/memory.c b/softmmu/memory.c
index 0043791361..bbc910b129 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -1895,6 +1895,7 @@ void memory_region_notify_one_iommu(IOMMUNotifier *notifier,
 {
     IOMMUNotifierFlag request_flags;
     hwaddr entry_end = entry->iova + entry->addr_mask;
+    IOMMUTLBEntry tmp = *entry;
 
     /*
      * Skip the notification if the notification does not overlap
@@ -1904,16 +1905,26 @@ void memory_region_notify_one_iommu(IOMMUNotifier *notifier,
         return;
     }
 
-    assert(entry->iova >= notifier->start && entry_end <= notifier->end);
+    if (notifier->notifier_flags & IOMMU_NOTIFIER_DEVIOTLB) {
+        /* Crop (iova, addr_mask) to range */
+        tmp.iova = MAX(tmp.iova, notifier->start);
+        tmp.addr_mask = MIN(entry_end, notifier->end) - tmp.iova;
+        /* Confirm no underflow */
+        assert(MIN(entry_end, notifier->end) >= tmp.iova);
+    } else {
+        assert(entry->iova >= notifier->start && entry_end <= notifier->end);
+    }
 
     if (entry->perm & IOMMU_RW) {
         request_flags = IOMMU_NOTIFIER_MAP;
+    } else if (notifier->notifier_flags == IOMMU_NOTIFIER_DEVIOTLB) {
+        request_flags = IOMMU_NOTIFIER_DEVIOTLB;
     } else {
         request_flags = IOMMU_NOTIFIER_UNMAP;
     }
 
     if (notifier->notifier_flags & request_flags) {
-        notifier->notify(notifier, entry);
+        notifier->notify(notifier, &tmp);
     }
 }
 
-- 
2.18.1

Re: [RFC v4 1/2] memory: Rename memory_region_notify_one to memory_region_notify_one_iommu

[Peter Xu]

On Tue, Aug 18, 2020 at 03:01:50PM +0200, Eugenio Pérez wrote:
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

It would be good if there's some commit message, though..

Also, I'd slightly prefer memory_region_notify_iommu_one rather than one_iommu,
but I'm fine with either.

-- 
Peter Xu

Re: [RFC v4 2/2] memory: Skip bad range assertion if notifier is DEVIOTLB type

[Peter Xu]

On Tue, Aug 18, 2020 at 03:01:51PM +0200, Eugenio Pérez wrote:
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>

The changes on the callers of memory_region_notify_one_iommu() seems to be
still missing (and, to embed the type into the notification process)..

-- 
Peter Xu

Re: [RFC v4 2/2] memory: Skip bad range assertion if notifier is DEVIOTLB type

[Eugenio Perez Martin]

On Wed, Aug 19, 2020 at 6:40 PM Peter Xu <peterx@redhat.com> wrote:
>
> On Tue, Aug 18, 2020 at 03:01:51PM +0200, Eugenio Pérez wrote:
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
>
> The changes on the callers of memory_region_notify_one_iommu() seems to be
> still missing (and, to embed the type into the notification process)..
>

Hi Peter.

I thought that these were left for a future patch series (the main
motivation was to avoid for guest code to hit the assertion).

Do you want me to put them in this series?

Thanks!

> --
> Peter Xu
>

Re: [RFC v4 2/2] memory: Skip bad range assertion if notifier is DEVIOTLB type

[Eugenio Perez Martin]

On Wed, Aug 19, 2020 at 7:47 PM Eugenio Perez Martin
<eperezma@redhat.com> wrote:
>
> On Wed, Aug 19, 2020 at 6:40 PM Peter Xu <peterx@redhat.com> wrote:
> >
> > On Tue, Aug 18, 2020 at 03:01:51PM +0200, Eugenio Pérez wrote:
> > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> >
> > The changes on the callers of memory_region_notify_one_iommu() seems to be
> > still missing (and, to embed the type into the notification process)..
> >
>
> Hi Peter.
>
> I thought that these were left for a future patch series (the main

s/that these were left/that we were going to left them/

> motivation was to avoid for guest code to hit the assertion).
>
> Do you want me to put them in this series?
>
> Thanks!
>
> > --
> > Peter Xu
> >

Re: [RFC v4 2/2] memory: Skip bad range assertion if notifier is DEVIOTLB type

[Peter Xu]

On Wed, Aug 19, 2020 at 07:47:32PM +0200, Eugenio Perez Martin wrote:
> On Wed, Aug 19, 2020 at 6:40 PM Peter Xu <peterx@redhat.com> wrote:
> >
> > On Tue, Aug 18, 2020 at 03:01:51PM +0200, Eugenio Pérez wrote:
> > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> >
> > The changes on the callers of memory_region_notify_one_iommu() seems to be
> > still missing (and, to embed the type into the notification process)..
> >
> 
> Hi Peter.
> 
> I thought that these were left for a future patch series (the main
> motivation was to avoid for guest code to hit the assertion).
> 
> Do you want me to put them in this series?

Imho it would be good to do that altogether.

For example, you have defined:

   /* Notify changes on device IOTLB entries */
   IOMMU_NOTIFIER_DEVIOTLB = 0x04,

The comment says we'll only notify on device iotlbs, however with the code
change we'll still notify even with normal iotlb invalidations (but always with
the type IOMMU_NOTIFIER_DEVIOTLB ).  IOW vhost with ats=on will still receive
two invalidations for the same range just like before.

-- 
Peter Xu