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Re: [Qemu-devel] [PATCH v4 2/2] enable multi-function hot-add

From: Cao jin
Subject: Re: [Qemu-devel] [PATCH v4 2/2] enable multi-function hot-add
Date: Fri, 23 Oct 2015 22:12:15 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 


On 10/23/2015 09:41 PM, Michael S. Tsirkin wrote:

On Fri, Oct 23, 2015 at 04:14:07PM +0800, Cao jin wrote:



On 10/23/2015 02:50 PM, Michael S. Tsirkin wrote:

On Fri, Oct 23, 2015 at 12:13:53PM +0800, Cao jin wrote:

Hi Michael

On 10/22/2015 10:37 PM, Michael S. Tsirkin wrote:

On Thu, Oct 22, 2015 at 07:57:52PM +0800, Cao jin wrote:

Enable pcie device multifunction hot, just ensure the function 0
added last, then driver will got the notification to scan all the
function in the slot.

Signed-off-by: Cao jin <address@hidden>
---
  hw/pci/pci.c         | 29 +++++++++++++++++++++++++++++
  hw/pci/pci_host.c    | 11 +++++++++--
  hw/pci/pcie.c        | 18 +++++++++---------
  include/hw/pci/pci.h |  1 +
  4 files changed, 48 insertions(+), 11 deletions(-)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index b0bf540..c068248 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -847,6 +847,7 @@ static PCIDevice *do_pci_register_device(PCIDevice 
*pci_dev, PCIBus *bus,
      PCIConfigWriteFunc *config_write = pc->config_write;
      Error *local_err = NULL;
      AddressSpace *dma_as;
+    DeviceState *dev = DEVICE(pci_dev);

      if (devfn < 0) {
          for(devfn = bus->devfn_min ; devfn < ARRAY_SIZE(bus->devices);
@@ -864,6 +865,16 @@ static PCIDevice *do_pci_register_device(PCIDevice 
*pci_dev, PCIBus *bus,
                     PCI_SLOT(devfn), PCI_FUNC(devfn), name,
                     bus->devices[devfn]->name);
          return NULL;
+    } else if (dev->hotplugged &&
+               ((!pc->is_express && bus->devices[PCI_DEVFN(PCI_SLOT(devfn), 
0)]) ||
+                (pc->is_express && bus->devices[0]))) {


So let's change pci_is_function_0 to pci_get_function_0 and reuse here?


ok, will modify it and all the following comment.




+        error_setg(errp, "PCI: slot %d function 0 already ocuppied by %s,"
+                   " new func %s cannot be exposed to guest.",
+                   PCI_SLOT(devfn),
+                   bus->devices[PCI_DEVFN(PCI_SLOT(devfn), 0)]->name,
+                   name);
+
+       return NULL;
      }

      pci_dev->bus = bus;
@@ -2454,6 +2465,24 @@ void pci_bus_get_w64_range(PCIBus *bus, Range *range)
      pci_for_each_device_under_bus(bus, pci_dev_get_w64, range);
  }

+/* ARI device function number range is 0-255, means has only 1 function0;
+ * while PCI device has 1 function0 in each slot(up to 32 slot) */
+bool pci_is_function_0(PCIDevice *pci_dev)
+{
+    PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(pci_dev);
+    bool is_func0 = false;
+
+    if (pc->is_express) {



This is not what the spec says. It says:
devices connected to an upstream port.


Yes, I am wrong here. I got confused about the ARI device definition in
spec:"a device associated with an Upstream Port". Because as I understand,
ARI device is a EP immediately below a ARI downstream port, just as Figure
6-13(Example System Topology with ARI Devices) shows in the spec, but where
is upstream port in the definition come from, what the relationship between
upstream port and a ARI device?


See Terms and Acronyms:
        The Port on a
        component that contains only Endpoint or Bridge Functions is an Upstream
        Port.


Thanks michael. if I understand right, ARI device has a upstream port on the
device, while on-ARI device doesn`t have?


That's what it says, isn't it?
Yup, seems it does is. it redefined the concept of device in my mind, because never seen a figure shows that there is a port on a ARI device, like the figure of "ARI Device X" I draw below 
-------------------------------
|       _______________       |
|      |_upstream port_|      |
|                             |
|                             |
|                             |
| F0  F1  F2 ... ..     F255  |
------------------------------|
Thanks for your time for this question, I will go on dealing with the other comments. 


But in Figure 6-13(Example System Topology with ARI Devices) in the PCIe
spec, don`t see any notation of upstream port on ARI Device X & Y, so maybe
figure 6-13 is incomplete?


You can see that they are connected to downstream or root ports.






+        if (!pci_dev->devfn)
+            is_func0 = true;


Just do return !pci_dev->devfn here.


+    } else {
+        if(!PCI_FUNC(pci_dev->devfn))
+            is_func0 = true;
+    }
+
+    return is_func0;
+}
+
  static const TypeInfo pci_device_type_info = {
      .name = TYPE_PCI_DEVICE,
      .parent = TYPE_DEVICE,
diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
index 3e26f92..40087c9 100644
--- a/hw/pci/pci_host.c
+++ b/hw/pci/pci_host.c
@@ -20,6 +20,7 @@

  #include "hw/pci/pci.h"
  #include "hw/pci/pci_host.h"
+#include "hw/pci/pci_bus.h"
  #include "trace.h"

  /* debug PCI */
@@ -75,7 +76,10 @@ void pci_data_write(PCIBus *s, uint32_t addr, uint32_t val, 
int len)
      PCIDevice *pci_dev = pci_dev_find_by_addr(s, addr);
      uint32_t config_addr = addr & (PCI_CONFIG_SPACE_SIZE - 1);

-    if (!pci_dev) {
+    /* non-zero functions are only exposed when function 0 is present,
+     * allowing direct removal of unexposed functions.
+     */
+    if (!pci_dev || !s->devices[PCI_DEVFN(PCI_SLOT(pci_dev->devfn), 0)]) {


Reuse pci_get_function_0 here too?


          return;
      }

@@ -91,7 +95,10 @@ uint32_t pci_data_read(PCIBus *s, uint32_t addr, int len)
      uint32_t config_addr = addr & (PCI_CONFIG_SPACE_SIZE - 1);
      uint32_t val;

-    if (!pci_dev) {
+    /* non-zero functions are only exposed when function 0 is present,
+     * allowing direct removal of unexposed functions.
+     */
+    if (!pci_dev || !s->devices[PCI_DEVFN(PCI_SLOT(pci_dev->devfn), 0)]) {


And here?


          return ~0x0;
      }

diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index b1adeaf..d0a8006 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -249,16 +249,16 @@ void pcie_cap_slot_hotplug_cb(HotplugHandler 
*hotplug_dev, DeviceState *dev,
          return;
      }

-    /* TODO: multifunction hot-plug.
-     * Right now, only a device of function = 0 is allowed to be
-     * hot plugged/unplugged.
+    /* To enable multifunction hot-plug, we just ensure the function
+     * 0 added last. Until function 0 added, we set the sltsta and
+     * inform OS via event notification.


Should be "when function 0 is added".


       */
-    assert(PCI_FUNC(pci_dev->devfn) == 0);
-
-    pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTSTA,
-                               PCI_EXP_SLTSTA_PDS);
-    pcie_cap_slot_event(PCI_DEVICE(hotplug_dev),
-                        PCI_EXP_HP_EV_PDC | PCI_EXP_HP_EV_ABP);
+    if (pci_is_function_0(pci_dev)) {
+        pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTSTA,
+                                   PCI_EXP_SLTSTA_PDS);
+        pcie_cap_slot_event(PCI_DEVICE(hotplug_dev),
+                            PCI_EXP_HP_EV_PDC | PCI_EXP_HP_EV_ABP);
+    }
  }

  static void pcie_unplug_device(PCIBus *bus, PCIDevice *dev, void *opaque)
diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index f5e7fd8..2820cfd 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -397,6 +397,7 @@ void pci_for_each_bus_depth_first(PCIBus *bus,
                                    void *(*begin)(PCIBus *bus, void 
*parent_state),
                                    void (*end)(PCIBus *bus, void *state),
                                    void *parent_state);
+bool pci_is_function_0(PCIDevice *pci_dev);

  /* Use this wrapper when specific scan order is not required. */
  static inline
--
2.1.0

.



--
Yours Sincerely,

Cao Jin

.



--
Yours Sincerely,

Cao Jin

.



--
Yours Sincerely,

Cao Jin
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