xen-platform: separate unplugging of NVMe disks

Commit 090fa1c8 "add support for unplugging NVMe disks..." extended the
existing disk unplug flag to cover NVMe disks as well as IDE and SCSI.

The recent thread on the xen-devel mailing list [1] has highlighted that
this is not desirable behaviour: PV frontends should be able to distinguish
NVMe disks from other types of disk and should have separate control over
whether they are unplugged.

This patch defines a new bit in the unplug mask for this purpose (see Xen
commit [2]) and also tidies up the definitions of, and improves the
comments regarding, the previously exiting bits in the protocol.

[1] https://lists.xen.org/archives/html/xen-devel/2017-03/msg02924.html
[2] http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=1096aa02

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>

1 files changed, 35 insertions, 12 deletions

diff --git a/hw/i386/xen/xen_platform.c b/hw/i386/xen/xen_platform.c
index f23155832b..9ba7474566 100644
--- a/hw/i386/xen/xen_platform.c
+++ b/hw/i386/xen/xen_platform.c
@@ -87,10 +87,30 @@ static void log_writeb(PCIXenPlatformState *s, char val)
     }
 }
 
-/* Xen Platform, Fixed IOPort */
-#define UNPLUG_ALL_DISKS 1
-#define UNPLUG_ALL_NICS 2
-#define UNPLUG_AUX_IDE_DISKS 4
+/*
+ * Unplug device flags.
+ *
+ * The logic got a little confused at some point in the past but this is
+ * what they do now.
+ *
+ * bit 0: Unplug all IDE and SCSI disks.
+ * bit 1: Unplug all NICs.
+ * bit 2: Unplug IDE disks except primary master. This is overridden if
+ *        bit 0 is also present in the mask.
+ * bit 3: Unplug all NVMe disks.
+ *
+ */
+#define _UNPLUG_IDE_SCSI_DISKS 0
+#define UNPLUG_IDE_SCSI_DISKS (1u << _UNPLUG_IDE_SCSI_DISKS)
+
+#define _UNPLUG_ALL_NICS 1
+#define UNPLUG_ALL_NICS (1u << _UNPLUG_ALL_NICS)
+
+#define _UNPLUG_AUX_IDE_DISKS 2
+#define UNPLUG_AUX_IDE_DISKS (1u << _UNPLUG_AUX_IDE_DISKS)
+
+#define _UNPLUG_NVME_DISKS 3
+#define UNPLUG_NVME_DISKS (1u << _UNPLUG_NVME_DISKS)
 
 static void unplug_nic(PCIBus *b, PCIDevice *d, void *o)
 {
@@ -122,7 +142,7 @@ static void unplug_disks(PCIBus *b, PCIDevice *d, void *opaque)
 {
     uint32_t flags = *(uint32_t *)opaque;
     bool aux = (flags & UNPLUG_AUX_IDE_DISKS) &&
-        !(flags & UNPLUG_ALL_DISKS);
+        !(flags & UNPLUG_IDE_SCSI_DISKS);
 
     /* We have to ignore passthrough devices */
     if (!strcmp(d->name, "xen-pci-passthrough")) {
@@ -135,12 +155,16 @@ static void unplug_disks(PCIBus *b, PCIDevice *d, void *opaque)
         break;
 
     case PCI_CLASS_STORAGE_SCSI:
-    case PCI_CLASS_STORAGE_EXPRESS:
         if (!aux) {
             object_unparent(OBJECT(d));
         }
         break;
 
+    case PCI_CLASS_STORAGE_EXPRESS:
+        if (flags & UNPLUG_NVME_DISKS) {
+            object_unparent(OBJECT(d));
+        }
+
     default:
         break;
     }
@@ -158,10 +182,9 @@ static void platform_fixed_ioport_writew(void *opaque, uint32_t addr, uint32_t v
     switch (addr) {
     case 0: {
         PCIDevice *pci_dev = PCI_DEVICE(s);
-        /* Unplug devices.  Value is a bitmask of which devices to
-           unplug, with bit 0 the disk devices, bit 1 the network
-           devices, and bit 2 the non-primary-master IDE devices. */
-        if (val & (UNPLUG_ALL_DISKS | UNPLUG_AUX_IDE_DISKS)) {
+        /* Unplug devices. See comment above flag definitions */
+        if (val & (UNPLUG_IDE_SCSI_DISKS | UNPLUG_AUX_IDE_DISKS |
+                   UNPLUG_NVME_DISKS)) {
             DPRINTF("unplug disks\n");
             pci_unplug_disks(pci_dev->bus, val);
         }
@@ -349,14 +372,14 @@ static void xen_platform_ioport_writeb(void *opaque, hwaddr addr,
              * If VMDP was to control both disk and LAN it would use 4.
              * If it controlled just disk or just LAN, it would use 8 below.
              */
-            pci_unplug_disks(pci_dev->bus, UNPLUG_ALL_DISKS);
+            pci_unplug_disks(pci_dev->bus, UNPLUG_IDE_SCSI_DISKS);
             pci_unplug_nics(pci_dev->bus);
         }
         break;
     case 8:
         switch (val) {
         case 1:
-            pci_unplug_disks(pci_dev->bus, UNPLUG_ALL_DISKS);
+            pci_unplug_disks(pci_dev->bus, UNPLUG_IDE_SCSI_DISKS);
             break;
         case 2:
             pci_unplug_nics(pci_dev->bus);