[Xen-devel] [PATCH qemu-xen-traditional 1/2] xen_platform: unplug also SCSI disks

[Olaf Hering <olaf@xxxxxxxxx>]

From: Olaf Hering <ohering@xxxxxxx>

Using 'vdev=sd[a-o]' will create an emulated LSI controller, which can
be used by the emulated BIOS to boot from disk. If the HVM domU has also
PV driver the disk may appear twice in the guest. To avoid this an
unplug of the emulated hardware is needed, similar to what is done for
IDE and NIC drivers already.

Since the SCSI controller provides only disks the entire controller can
be unplugged at once.

Impact of the change for classic and pvops based guest kernels:

 vdev=sda:disk0
before: pvops:   disk0=pv xvda + emulated sda
        classic: disk0=pv sda  + emulated sdq
after:  pvops:   disk0=pv xvda
        classic: disk0=pv sda

 vdev=hda:disk0, vdev=sda:disk1
before: pvops:   disk0=pv xvda
                 disk1=emulated sda
        classic: disk0=pv hda
                 disk1=pv sda  + emulated sdq
after:  pvops:   disk0=pv xvda
                 disk1=not accessible by blkfront, index hda==index sda
        classic: disk0=pv hda
                 disk1=pv sda

 vdev=hda:disk0, vdev=sda:disk1, vdev=sdb:disk2
before: pvops:   disk0=pv xvda
                 disk1=emulated sda
                 disk2=pv xvdb + emulated sdb
        classic: disk0=pv hda
                 disk1=pv sda  + emulated sdq
                 disk2=pv sdb  + emulated sdr
after:  pvops:   disk0=pv xvda
                 disk1=not accessible by blkfront, index hda==index sda
                 disk2=pv xvdb
        classic: disk0=pv hda
                 disk1=pv sda
                 disk2=pv sda

Upstream commit 78f66897ddf58d1ffe5e0b95f7c1a1dad103a8da

Signed-off-by: Olaf Hering <ohering@xxxxxxx>
---
 hw/pci.c          | 41 +++++++++++++++++++++++++++++++++++++++++
 hw/xen_platform.c |  4 +++-
 qemu-xen.h        |  1 +
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/hw/pci.c b/hw/pci.c
index c423285..7d8e3b6 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -871,6 +871,47 @@ void pci_unplug_netifs(void)
     }
 }
 
+void pci_unplug_scsi(void)
+{
+    PCIBus *bus;
+    PCIDevice *dev;
+    PCIIORegion *region;
+    int x;
+    int i;
+
+    /* We only support one PCI bus */
+    for (bus = first_bus; bus; bus = NULL) {
+       for (x = 0; x < 256; x++) {
+           dev = bus->devices[x];
+           if (dev &&
+               dev->config[0xa] == 0 &&
+               dev->config[0xb] == 1
+#ifdef CONFIG_PASSTHROUGH
+               && test_pci_devfn(x) != 1
+#endif
+               ) {
+               /* Found a scsi disk.  Remove it from the bus.  Note that
+                  we don't free it here, since there could still be
+                  references to it floating around.  There are only
+                  ever one or two structures leaked, and it's not
+                  worth finding them all. */
+               bus->devices[x] = NULL;
+               for (i = 0; i < PCI_NUM_REGIONS; i++) {
+                   region = &dev->io_regions[i];
+                   if (region->addr == (uint32_t)-1 ||
+                       region->size == 0)
+                       continue;
+                   if (region->type == PCI_ADDRESS_SPACE_IO) {
+                       isa_unassign_ioport(region->addr, region->size);
+                   } else if (region->type == PCI_ADDRESS_SPACE_MEM) {
+                       unregister_iomem(region->addr);
+                   }
+               }
+           }
+       }
+    }
+}
+
 typedef struct {
     PCIDevice dev;
     PCIBus *bus;
diff --git a/hw/xen_platform.c b/hw/xen_platform.c
index d282f8e..0a94e0d 100644
--- a/hw/xen_platform.c
+++ b/hw/xen_platform.c
@@ -154,8 +154,10 @@ static void platform_fixed_ioport_write2(void *opaque, 
uint32_t addr, uint32_t v
         /* Unplug devices.  Value is a bitmask of which devices to
            unplug, with bit 0 the IDE devices, bit 1 the network
            devices, and bit 2 the non-primary-master IDE devices. */
-        if (val & UNPLUG_ALL_IDE_DISKS)
+        if (val & UNPLUG_ALL_IDE_DISKS) {
             ide_unplug_harddisks();
+            pci_unplug_scsi();
+        }
         if (val & UNPLUG_ALL_NICS) {
             pci_unplug_netifs();
             net_tap_shutdown_all();
diff --git a/qemu-xen.h b/qemu-xen.h
index 0598668..d315623 100644
--- a/qemu-xen.h
+++ b/qemu-xen.h
@@ -47,6 +47,7 @@ void unset_vram_mapping(void *opaque);
 #endif
 
 void pci_unplug_netifs(void);
+void pci_unplug_scsi(void);
 void destroy_hvm_domain(void);
 void unregister_iomem(target_phys_addr_t start);
 

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