[Xen-devel] [PATCH v2 2/2] xl: Add "seize" option to PCI devices

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

The "seize" option tells the toolstack to attempt to automatically
unbind devices and re-bind them to the pciback driver.  This should
make creating VMs that habitually use pass-through (such as driver domain
VMs and gaming VMs) easier to use and manage.

Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
---
v2:
 - Include LIBXL_HAVE_DEVICE_PCI_SEIZE in libxl.h

CC: Ian Jackson <ian.jackson@xxxxxxxxxx>
CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 docs/man/xl.cfg.pod.5       |   14 ++++++++++++++
 tools/libxl/libxl.h         |   10 ++++++++++
 tools/libxl/libxl_pci.c     |    6 ++++++
 tools/libxl/libxl_types.idl |    1 +
 tools/libxl/libxlu_pci.c    |    2 ++
 tools/libxl/xl_cmdimpl.c    |    5 +++++
 6 files changed, 38 insertions(+)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index e15a49f..946b438 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -509,6 +509,15 @@ the PCI device regardless whether the guest uses INTx or 
MSI. Some
 device drivers, such as NVIDIA's, detect an inconsistency and do not
 function when this option is enabled. Therefore the default is false (0).
 
+=item B<seize=BOOLEAN>
+
+Tells xl to automatically attempt to re-assign a device to
+pciback if it is not already assigned.  
+
+WARNING: If you set this option, xl will gladly re-assign a critical
+system device, such as a network or a disk controller being used by
+dom0 without confirmation.  Please use with care.
+
 =item B<power_mgmt=BOOLEAN>
 
 (HVM only) Specifies that the VM should be able to program the
@@ -530,6 +539,11 @@ above.
 Changes the default value of 'msitranslate' for all PCI devices passed
 through to this VM. See L<msitranslate|/"msitranslate_boolean"> above.
 
+=item B<pci_seize=BOOLEAN>
+
+Changes the default value of 'seize' for all PCI devices passed
+through to this VM. See L<seize|/"seize_boolean"> above.
+
 =item B<pci_power_mgmt=BOOLEAN>
 
 (HVM only) Changes the default value of 'power_mgmt' for all PCI
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 06bbca6..3b5c0a5 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -445,6 +445,16 @@
 #define LIBXL_HAVE_NO_SUSPEND_RESUME 1
 #endif
 
+/*
+ * LIBXL_HAVE_DEVICE_PCI_SEIZE
+ * 
+ * If this is defined, then the libxl_device_pci struct will contain
+ * the "seize" boolean field.  If this field is set, libxl_pci_add will
+ * check to see if the device is currently assigned to pciback, and if not,
+ * it will attempt to do so (unbinding the device from the existing driver).
+ */
+#define LIBXL_HAVE_DEVICE_PCI_SEIZE 1
+
 /* Functions annotated with LIBXL_EXTERNAL_CALLERS_ONLY may not be
  * called from within libxl itself. Callers outside libxl, who
  * do not #include libxl_internal.h, are fine. */
diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
index 2e52470..44d0453 100644
--- a/tools/libxl/libxl_pci.c
+++ b/tools/libxl/libxl_pci.c
@@ -1050,6 +1050,12 @@ int libxl__device_pci_add(libxl__gc *gc, uint32_t domid, 
libxl_device_pci *pcide
     rc = libxl__device_pci_setdefault(gc, pcidev);
     if (rc) goto out;
 
+    if (pcidev->seize && !pciback_dev_is_assigned(gc, pcidev)) {
+        rc = libxl__device_pci_assignable_add(gc, pcidev, 1);
+        if ( rc )
+            goto out;
+    }
+
     if (!libxl_pcidev_assignable(ctx, pcidev)) {
         LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "PCI device %x:%x:%x.%x is not 
assignable",
                    pcidev->domain, pcidev->bus, pcidev->dev, pcidev->func);
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 649ce50..7d3a62b 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -444,6 +444,7 @@ libxl_device_pci = Struct("device_pci", [
     ("msitranslate", bool),
     ("power_mgmt", bool),
     ("permissive", bool),
+    ("seize", bool),
     ])
 
 libxl_device_vtpm = Struct("device_vtpm", [
diff --git a/tools/libxl/libxlu_pci.c b/tools/libxl/libxlu_pci.c
index f5dee93..26fb143 100644
--- a/tools/libxl/libxlu_pci.c
+++ b/tools/libxl/libxlu_pci.c
@@ -141,6 +141,8 @@ int xlu_pci_parse_bdf(XLU_Config *cfg, libxl_device_pci 
*pcidev, const char *str
                     pcidev->power_mgmt = atoi(tok);
                 }else if ( !strcmp(optkey, "permissive") ) {
                     pcidev->permissive = atoi(tok);
+                }else if ( !strcmp(optkey, "seize") ) {
+                    pcidev->seize = atoi(tok);
                 }else{
                     XLU__PCI_ERR(cfg, "Unknown PCI BDF option: %s", optkey);
                 }
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 4fc46eb..5f59bbc 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -737,6 +737,7 @@ static void parse_config_data(const char *config_source,
     int pci_power_mgmt = 0;
     int pci_msitranslate = 0;
     int pci_permissive = 0;
+    int pci_seize = 0;
     int i, e;
 
     libxl_domain_create_info *c_info = &d_config->c_info;
@@ -1462,6 +1463,9 @@ skip_vfb:
     if (!xlu_cfg_get_long (config, "pci_permissive", &l, 0))
         pci_permissive = l;
 
+    if (!xlu_cfg_get_long (config, "pci_seize", &l, 0))
+        pci_seize = l;
+
     /* To be reworked (automatically enabled) once the auto ballooning
      * after guest starts is done (with PCI devices passed in). */
     if (c_info->type == LIBXL_DOMAIN_TYPE_PV) {
@@ -1481,6 +1485,7 @@ skip_vfb:
             pcidev->msitranslate = pci_msitranslate;
             pcidev->power_mgmt = pci_power_mgmt;
             pcidev->permissive = pci_permissive;
+            pcidev->seize = pci_seize;
             if (!xlu_pci_parse_bdf(config, pcidev, buf))
                 d_config->num_pcidevs++;
         }
-- 
1.7.9.5


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