Re: [Qemu-devel] [PATCH v3 2/2] remove function during multi-function hot-add

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Oct 13, 2015 at 05:54:34PM +0800, Cao jin wrote:
> Hi Michael
> 
> On 10/13/2015 04:51 PM, Michael S. Tsirkin wrote:
> >On Tue, Oct 13, 2015 at 04:41:35PM +0800, Cao jin wrote:
> >>In case user regret when hot-adding multi-function, should roll back,
> >>device_del the function added but not exposed to the guest.
> >>
> >>Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
> >
> >I think this patch should come first, before we enable the
> >functionality that depends on it.
> >
> Do you mean, the function should be removed individually in any condition?

I just mean the patches in the series should be reordered.

> Because as you know, device_del pci_dev will remove all the functions in the
> slot that are fulled exposed to the guest, Alex also mentioned this
> limitation before.
> >
> >>---
> >>  hw/pci/pci_host.c |  6 +++++-
> >>  hw/pci/pcie.c     | 22 +++++++++++++++++-----
> >>  2 files changed, 22 insertions(+), 6 deletions(-)
> >>
> >>diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
> >>index 3e26f92..35e5cf3 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 */
> >>@@ -88,10 +89,13 @@ void pci_data_write(PCIBus *s, uint32_t addr, uint32_t val, int len)
> >>  uint32_t pci_data_read(PCIBus *s, uint32_t addr, int len)
> >>  {
> >>      PCIDevice *pci_dev = pci_dev_find_by_addr(s, addr);
> >>+    PCIDevice *f0 = NULL;
> >>      uint32_t config_addr = addr & (PCI_CONFIG_SPACE_SIZE - 1);
> >>      uint32_t val;
> >>+    uint8_t slot = (addr >> 11) & 0x1F;
> >>
> >>-    if (!pci_dev) {
> >>+    f0 = s->devices[PCI_DEVFN(slot, 0)];
> >>+    if (!pci_dev || (!f0 && pci_dev)) {
> >>          return ~0x0;
> >>      }
> >>
> >>diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> >>index 89bf61b..58d2153 100644
> >>--- a/hw/pci/pcie.c
> >>+++ b/hw/pci/pcie.c
> >>@@ -261,13 +261,30 @@ void pcie_cap_slot_hotplug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
> >>      }
> >>  }
> >>
> >>+static void pcie_unplug_device(PCIBus *bus, PCIDevice *dev, void *opaque)
> >>+{
> >>+    object_unparent(OBJECT(dev));
> >>+}
> >>+
> >>  void pcie_cap_slot_hot_unplug_request_cb(HotplugHandler *hotplug_dev,
> >>                                           DeviceState *dev, Error **errp)
> >>  {
> >>      uint8_t *exp_cap;
> >>+    PCIDevice *pci_dev = PCI_DEVICE(dev);
> >>+    PCIBus *bus = pci_dev->bus;
> >>
> >>      pcie_cap_slot_hotplug_common(PCI_DEVICE(hotplug_dev), dev, &exp_cap, errp);
> >>
> >>+    /* In case user regret when hot-adding multi function, remove the function
> >>+     * that is unexposed to guest individually, without interaction with guest.
> >>+     */
> >>+    if (PCI_FUNC(pci_dev->devfn) > 0 &&
> >>+            bus->devices[PCI_DEVFN(PCI_SLOT(pci_dev->devfn), 0)] == NULL) {
> >>+        pcie_unplug_device(bus, pci_dev, NULL);
> >>+
> >>+        return;
> >>+    }
> >>+
> >>      pcie_cap_slot_push_attention_button(PCI_DEVICE(hotplug_dev));
> >>  }
> >>
> >>@@ -378,11 +395,6 @@ void pcie_cap_slot_reset(PCIDevice *dev)
> >>      hotplug_event_update_event_status(dev);
> >>  }
> >>
> >>-static void pcie_unplug_device(PCIBus *bus, PCIDevice *dev, void *opaque)
> >>-{
> >>-    object_unparent(OBJECT(dev));
> >>-}
> >>-
> >>  void pcie_cap_slot_write_config(PCIDevice *dev,
> >>                                  uint32_t addr, uint32_t val, int len)
> >>  {
> >>--
> >>2.1.0
> >.
> >
> 
> -- 
> Yours Sincerely,
> 
> Cao Jin