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Re: [Qemu-devel] [PULL 03/36] hw/pci: delay bus_master_enable_region ini

From: Marcel Apfelbaum
Subject: Re: [Qemu-devel] [PULL 03/36] hw/pci: delay bus_master_enable_region initialization
Date: Sat, 9 Jul 2016 10:07:53 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 
On 07/09/2016 04:34 AM, Mark Cave-Ayland wrote:

On 04/07/16 17:46, Michael S. Tsirkin wrote:


From: Marcel Apfelbaum <address@hidden>

Skip bus_master_enable region creation on PCI device init
in order to be sure the IOMMU device (if present) would
be created in advance. Add this memory region at machine_done time.

Signed-off-by: Marcel Apfelbaum <address@hidden>
Reviewed-by: Michael S. Tsirkin <address@hidden>
Signed-off-by: Michael S. Tsirkin <address@hidden>
---
  include/hw/pci/pci_bus.h |  2 ++
  include/sysemu/sysemu.h  |  1 +
  hw/pci/pci.c             | 41 ++++++++++++++++++++++++++++++++---------
  vl.c                     |  5 +++++
  4 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
index 403fec6..5484a9b 100644
--- a/include/hw/pci/pci_bus.h
+++ b/include/hw/pci/pci_bus.h
@@ -39,6 +39,8 @@ struct PCIBus {
         Keep a count of the number of devices with raised IRQs.  */
      int nirq;
      int *irq_count;
+
+    Notifier machine_done;
  };

  typedef struct PCIBridgeWindows PCIBridgeWindows;
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 7313673..ee7c760 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -75,6 +75,7 @@ void qemu_add_exit_notifier(Notifier *notify);
  void qemu_remove_exit_notifier(Notifier *notify);

  void qemu_add_machine_init_done_notifier(Notifier *notify);
+void qemu_remove_machine_init_done_notifier(Notifier *notify);

  void hmp_savevm(Monitor *mon, const QDict *qdict);
  int load_vmstate(const char *name);
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 4b585f4..ee385eb 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -78,10 +78,37 @@ static const VMStateDescription vmstate_pcibus = {
      }
  };

+static void pci_init_bus_master(PCIDevice *pci_dev)
+{
+    AddressSpace *dma_as = pci_device_iommu_address_space(pci_dev);
+
+    memory_region_init_alias(&pci_dev->bus_master_enable_region,
+                             OBJECT(pci_dev), "bus master",
+                             dma_as->root, 0, 
memory_region_size(dma_as->root));
+    memory_region_set_enabled(&pci_dev->bus_master_enable_region, false);
+    address_space_init(&pci_dev->bus_master_as,
+                       &pci_dev->bus_master_enable_region, pci_dev->name);
+}
+
+static void pcibus_machine_done(Notifier *notifier, void *data)
+{
+    PCIBus *bus = container_of(notifier, PCIBus, machine_done);
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(bus->devices); ++i) {
+        if (bus->devices[i]) {
+            pci_init_bus_master(bus->devices[i]);
+        }
+    }
+}
+
  static void pci_bus_realize(BusState *qbus, Error **errp)
  {
      PCIBus *bus = PCI_BUS(qbus);

+    bus->machine_done.notify = pcibus_machine_done;
+    qemu_add_machine_init_done_notifier(&bus->machine_done);
+
      vmstate_register(NULL, -1, &vmstate_pcibus, bus);
  }

@@ -89,6 +116,8 @@ static void pci_bus_unrealize(BusState *qbus, Error **errp)
  {
      PCIBus *bus = PCI_BUS(qbus);

+    qemu_remove_machine_init_done_notifier(&bus->machine_done);
+
      vmstate_unregister(NULL, &vmstate_pcibus, bus);
  }

@@ -920,7 +949,6 @@ static PCIDevice *do_pci_register_device(PCIDevice 
*pci_dev, PCIBus *bus,
      PCIConfigReadFunc *config_read = pc->config_read;
      PCIConfigWriteFunc *config_write = pc->config_write;
      Error *local_err = NULL;
-    AddressSpace *dma_as;
      DeviceState *dev = DEVICE(pci_dev);

      pci_dev->bus = bus;
@@ -961,15 +989,10 @@ static PCIDevice *do_pci_register_device(PCIDevice 
*pci_dev, PCIBus *bus,

      pci_dev->devfn = devfn;
      pci_dev->requester_id_cache = pci_req_id_cache_get(pci_dev);
-    dma_as = pci_device_iommu_address_space(pci_dev);
-
-    memory_region_init_alias(&pci_dev->bus_master_enable_region,
-                             OBJECT(pci_dev), "bus master",
-                             dma_as->root, 0, 
memory_region_size(dma_as->root));
-    memory_region_set_enabled(&pci_dev->bus_master_enable_region, false);
-    address_space_init(&pci_dev->bus_master_as, 
&pci_dev->bus_master_enable_region,
-                       name);

+    if (qdev_hotplug) {
+        pci_init_bus_master(pci_dev);
+    }
      pstrcpy(pci_dev->name, sizeof(pci_dev->name), name);
      pci_dev->irq_state = 0;
      pci_config_alloc(pci_dev);
diff --git a/vl.c b/vl.c
index 9bb7f4c..5cd0f2a 100644
--- a/vl.c
+++ b/vl.c
@@ -2675,6 +2675,11 @@ void qemu_add_machine_init_done_notifier(Notifier 
*notify)
      }
  }

+void qemu_remove_machine_init_done_notifier(Notifier *notify)
+{
+    notifier_remove(notify);
+}
+
  static void qemu_run_machine_init_done_notifiers(void)
  {
      notifier_list_notify(&machine_init_done_notifiers, NULL);



Unfortunately this patch causes a regression booting my Debian 7.8.0 and
NetBSD 7.0 test images under qemu-system-sparc64 when accessing the
CDROM device, and rather unusually causes the qemu-system-sparc64
executable itself to segfault:



Hi Mark,
Thank you for finding it, can you please provide a command line and maybe one 
of your test images?
I'll be sure to address it.

Thanks,
Marcel



Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffe8453700 (LWP 21454)]
0x000000000041494a in address_space_lookup_region (d=0x0,
addr=3221225472, resolve_subpage=true) at
/home/build/src/qemu/git/qemu/exec.c:359
359         MemoryRegionSection *section = atomic_read(&d->mru_section);
(gdb) bt
#0  0x000000000041494a in address_space_lookup_region (d=0x0,
addr=3221225472, resolve_subpage=true) at
/home/build/src/qemu/git/qemu/exec.c:359
#1  0x0000000000414aa7 in address_space_translate_internal (d=0x0,
addr=3221225472, xlat=0x7fffe8451c40, plen=0x7fffe8451d10,
resolve_subpage=true) at /home/build/src/qemu/git/qemu/exec.c:390
#2  0x0000000000414c8f in address_space_translate (as=0x1961600,
addr=3221225472, xlat=0x7fffe8451d18, plen=0x7fffe8451d10,
is_write=false) at /home/build/src/qemu/git/qemu/exec.c:428
#3  0x000000000041a4be in address_space_read_full (as=0x1961600,
addr=3221225472, attrs=..., buf=0x7fffe8451f10 "\030(\226\001", len=8)
at /home/build/src/qemu/git/qemu/exec.c:2724
#4  0x000000000041a5b3 in address_space_read (len=8, buf=0x7fffe8451f10
"\030(\226\001", attrs=..., addr=3221225472, as=0x1961600) at
/home/build/src/qemu/git/qemu/include/exec/memory.h:1460
#5  address_space_rw (as=0x1961600, addr=3221225472, attrs=...,
buf=0x7fffe8451f10 "\030(\226\001", len=8, is_write=false) at
/home/build/src/qemu/git/qemu/exec.c:2739
#6  0x00000000005c71e0 in dma_memory_rw_relaxed (as=0x1961600,
addr=3221225472, buf=0x7fffe8451f10, len=8, dir=DMA_DIRECTION_TO_DEVICE)
at /home/build/src/qemu/git/qemu/include/sysemu/dma.h:87
#7  0x00000000005c7258 in dma_memory_rw (as=0x1961600, addr=3221225472,
buf=0x7fffe8451f10, len=8, dir=DMA_DIRECTION_TO_DEVICE) at
/home/build/src/qemu/git/qemu/include/sysemu/dma.h:110
#8  0x00000000005c72fa in pci_dma_rw (dev=0x19613f0, addr=3221225472,
buf=0x7fffe8451f10, len=8, dir=DMA_DIRECTION_TO_DEVICE) at
/home/build/src/qemu/git/qemu/include/hw/pci/pci.h:731
#9  0x00000000005c735a in pci_dma_read (dev=0x19613f0, addr=3221225472,
buf=0x7fffe8451f10, len=8) at
/home/build/src/qemu/git/qemu/include/hw/pci/pci.h:738
#10 0x00000000005c7980 in bmdma_rw_buf (dma=0x1962fa8, is_write=1) at
hw/ide/pci.c:139
#11 0x00000000005c4372 in ide_atapi_cmd_read_dma_cb (opaque=0x1962550,
ret=0) at hw/ide/atapi.c:413
#12 0x00000000005c7dfe in bmdma_cmd_writeb (bm=0x1962fa8, val=9) at
hw/ide/pci.c:245
#13 0x00000000005c91a9 in bmdma_write (opaque=0x1962fa8, addr=0, val=9,
size=1) at hw/ide/cmd646.c:219
#14 0x0000000000469fb8 in memory_region_write_accessor (mr=0x1963100,
addr=0, value=0x7fffe8452148, size=1, shift=0, mask=255, attrs=...) at
/home/build/src/qemu/git/qemu/memory.c:525
#15 0x000000000046a1e4 in access_with_adjusted_size (addr=0,
value=0x7fffe8452148, size=1, access_size_min=1, access_size_max=4,
access=0x469ec1 <memory_region_write_accessor>, mr=0x1963100, attrs=...)
     at /home/build/src/qemu/git/qemu/memory.c:586
#16 0x000000000046d42b in memory_region_dispatch_write (mr=0x1963100,
addr=0, data=9, size=1, attrs=...) at
/home/build/src/qemu/git/qemu/memory.c:1262
#17 0x000000000041a051 in address_space_write_continue (as=0x12bb4b0,
addr=2190466908936, attrs=..., buf=0x7fffe8452323 "\t\376\001", len=1,
addr1=0, l=1, mr=0x1963100) at /home/build/src/qemu/git/qemu/exec.c:2590
#18 0x000000000041a1c3 in address_space_write (as=0x12bb4b0,
addr=2190466908936, attrs=..., buf=0x7fffe8452323 "\t\376\001", len=1)
at /home/build/src/qemu/git/qemu/exec.c:2635
#19 0x000000000041a569 in address_space_rw (as=0x12bb4b0,
addr=2190466908936, attrs=..., buf=0x7fffe8452323 "\t\376\001", len=1,
is_write=true) at /home/build/src/qemu/git/qemu/exec.c:2737
#20 0x000000000041c27d in address_space_stb (as=0x12bb4b0,
addr=2190466908936, val=9, attrs=..., result=0x0) at
/home/build/src/qemu/git/qemu/exec.c:3477
#21 0x000000000041c2f5 in stb_phys (as=0x12bb4b0, addr=2190466908936,
val=9) at /home/build/src/qemu/git/qemu/exec.c:3485
#22 0x0000000000504759 in helper_st_asi (env=0x12d57e8,
addr=2190466908936, val=9, asi=29, size=1) at
/home/build/src/qemu/git/qemu/target-sparc/ldst_helper.c:1801
#23 0x00000000405bf4b0 in code_gen_buffer ()
#24 0x0000000000420c97 in cpu_tb_exec (cpu=0x12cd570,
itb=0x7fffe8fc10c0) at /home/build/src/qemu/git/qemu/cpu-exec.c:166
#25 0x0000000000421882 in cpu_loop_exec_tb (cpu=0x12cd570,
tb=0x7fffe8fc10c0, last_tb=0x7fffe8452988, tb_exit=0x7fffe8452984,
sc=0x7fffe84529a0) at /home/build/src/qemu/git/qemu/cpu-exec.c:530
#26 0x0000000000421b40 in cpu_exec (cpu=0x12cd570) at
/home/build/src/qemu/git/qemu/cpu-exec.c:626
#27 0x0000000000451e6b in tcg_cpu_exec (cpu=0x12cd570) at
/home/build/src/qemu/git/qemu/cpus.c:1541
#28 0x0000000000451f6d in tcg_exec_all () at
/home/build/src/qemu/git/qemu/cpus.c:1574
#29 0x00000000004510b4 in qemu_tcg_cpu_thread_fn (arg=0x12cd570) at
/home/build/src/qemu/git/qemu/cpus.c:1171
#30 0x00007ffff264bb50 in start_thread (arg=<optimized out>) at
pthread_create.c:304
#31 0x00007ffff2395fbd in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#32 0x0000000000000000 in ?? ()
(gdb)



ATB,

Mark.
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