Merge tag 'stable/for-linus-4.0-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen bug fixes from David Vrabel:

 - fix a PV regression in 3.19.

 - fix a dom0 crash on hosts with large numbers of PIRQs.

 - prevent pcifront from disabling memory or I/O port access, which may
   trigger host crashes.

* tag 'stable/for-linus-4.0-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen-pciback: limit guest control of command register
  xen/events: avoid NULL pointer dereference in dom0 on large machines
  xen: Remove trailing semicolon from xenbus_register_frontend() definition
  x86/xen: correct bug in p2m list initialization

6 files changed, 66 insertions, 23 deletions

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 740ae3026a14..9f93af56a5fc 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -563,7 +563,7 @@ static bool alloc_p2m(unsigned long pfn)
                 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
                         p2m_init(p2m);
                 else
-                        p2m_init_identity(p2m, pfn);
+                        p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
 
                 spin_lock_irqsave(&p2m_update_lock, flags);
 
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index b4bca2d4a7e5..70fba973a107 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -526,20 +526,26 @@ static unsigned int __startup_pirq(unsigned int irq)
         pirq_query_unmask(irq);
 
         rc = set_evtchn_to_irq(evtchn, irq);
-        if (rc != 0) {
-                pr_err("irq%d: Failed to set port to irq mapping (%d)\n",
-                       irq, rc);
-                xen_evtchn_close(evtchn);
-                return 0;
-        }
+        if (rc)
+                goto err;
+
         bind_evtchn_to_cpu(evtchn, 0);
         info->evtchn = evtchn;
 
+        rc = xen_evtchn_port_setup(info);
+        if (rc)
+                goto err;
+
 out:
         unmask_evtchn(evtchn);
         eoi_pirq(irq_get_irq_data(irq));
 
         return 0;
+
+err:
+        pr_err("irq%d: Failed to set port to irq mapping (%d)\n", irq, rc);
+        xen_evtchn_close(evtchn);
+        return 0;
 }
 
 static unsigned int startup_pirq(struct irq_data *data)
diff --git a/drivers/xen/xen-pciback/conf_space.c b/drivers/xen/xen-pciback/conf_space.c
index 46ae0f9f02ad..75fe3d466515 100644
--- a/drivers/xen/xen-pciback/conf_space.c
+++ b/drivers/xen/xen-pciback/conf_space.c
@@ -16,7 +16,7 @@
 #include "conf_space.h"
 #include "conf_space_quirks.h"
 
-static bool permissive;
+bool permissive;
 module_param(permissive, bool, 0644);
 
 /* This is where xen_pcibk_read_config_byte, xen_pcibk_read_config_word,
diff --git a/drivers/xen/xen-pciback/conf_space.h b/drivers/xen/xen-pciback/conf_space.h
index e56c934ad137..2e1d73d1d5d0 100644
--- a/drivers/xen/xen-pciback/conf_space.h
+++ b/drivers/xen/xen-pciback/conf_space.h
@@ -64,6 +64,8 @@ struct config_field_entry {
         void *data;
 };
 
+extern bool permissive;
+
 #define OFFSET(cfg_entry) ((cfg_entry)->base_offset+(cfg_entry)->field->offset)
 
 /* Add fields to a device - the add_fields macro expects to get a pointer to
diff --git a/drivers/xen/xen-pciback/conf_space_header.c b/drivers/xen/xen-pciback/conf_space_header.c
index c5ee82587e8c..2d7369391472 100644
--- a/drivers/xen/xen-pciback/conf_space_header.c
+++ b/drivers/xen/xen-pciback/conf_space_header.c
@@ -11,6 +11,10 @@
 #include "pciback.h"
 #include "conf_space.h"
 
+struct pci_cmd_info {
+        u16 val;
+};
+
 struct pci_bar_info {
         u32 val;
         u32 len_val;
@@ -20,22 +24,36 @@ struct pci_bar_info {
 #define is_enable_cmd(value) ((value)&(PCI_COMMAND_MEMORY|PCI_COMMAND_IO))
 #define is_master_cmd(value) ((value)&PCI_COMMAND_MASTER)
 
-static int command_read(struct pci_dev *dev, int offset, u16 *value, void *data)
+/* Bits guests are allowed to control in permissive mode. */
+#define PCI_COMMAND_GUEST (PCI_COMMAND_MASTER|PCI_COMMAND_SPECIAL| \
+                           PCI_COMMAND_INVALIDATE|PCI_COMMAND_VGA_PALETTE| \
+                           PCI_COMMAND_WAIT|PCI_COMMAND_FAST_BACK)
+
+static void *command_init(struct pci_dev *dev, int offset)
 {
-        int i;
-        int ret;
-
-        ret = xen_pcibk_read_config_word(dev, offset, value, data);
-        if (!pci_is_enabled(dev))
-                return ret;
-
-        for (i = 0; i < PCI_ROM_RESOURCE; i++) {
-                if (dev->resource[i].flags & IORESOURCE_IO)
-                        *value |= PCI_COMMAND_IO;
-                if (dev->resource[i].flags & IORESOURCE_MEM)
-                        *value |= PCI_COMMAND_MEMORY;
+        struct pci_cmd_info *cmd = kmalloc(sizeof(*cmd), GFP_KERNEL);
+        int err;
+
+        if (!cmd)
+                return ERR_PTR(-ENOMEM);
+
+        err = pci_read_config_word(dev, PCI_COMMAND, &cmd->val);
+        if (err) {
+                kfree(cmd);
+                return ERR_PTR(err);
         }
 
+        return cmd;
+}
+
+static int command_read(struct pci_dev *dev, int offset, u16 *value, void *data)
+{
+        int ret = pci_read_config_word(dev, offset, value);
+        const struct pci_cmd_info *cmd = data;
+
+        *value &= PCI_COMMAND_GUEST;
+        *value |= cmd->val & ~PCI_COMMAND_GUEST;
+
         return ret;
 }
 
@@ -43,6 +61,8 @@ static int command_write(struct pci_dev *dev, int offset, u16 value, void *data)
 {
         struct xen_pcibk_dev_data *dev_data;
         int err;
+        u16 val;
+        struct pci_cmd_info *cmd = data;
 
         dev_data = pci_get_drvdata(dev);
         if (!pci_is_enabled(dev) && is_enable_cmd(value)) {
@@ -83,6 +103,19 @@ static int command_write(struct pci_dev *dev, int offset, u16 value, void *data)
                 }
         }
 
+        cmd->val = value;
+
+        if (!permissive && (!dev_data || !dev_data->permissive))
+                return 0;
+
+        /* Only allow the guest to control certain bits. */
+        err = pci_read_config_word(dev, offset, &val);
+        if (err || val == value)
+                return err;
+
+        value &= PCI_COMMAND_GUEST;
+        value |= val & ~PCI_COMMAND_GUEST;
+
         return pci_write_config_word(dev, offset, value);
 }
 
@@ -282,6 +315,8 @@ static const struct config_field header_common[] = {
         {
          .offset    = PCI_COMMAND,
          .size      = 2,
+         .init      = command_init,
+         .release   = bar_release,
          .u.w.read  = command_read,
          .u.w.write = command_write,
         },
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index b78f21caf55a..b0f1c9e5d687 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -114,9 +114,9 @@ int __must_check __xenbus_register_backend(struct xenbus_driver *drv,
                                            const char *mod_name);
 
 #define xenbus_register_frontend(drv) \
-        __xenbus_register_frontend(drv, THIS_MODULE, KBUILD_MODNAME);
+        __xenbus_register_frontend(drv, THIS_MODULE, KBUILD_MODNAME)
 #define xenbus_register_backend(drv) \
-        __xenbus_register_backend(drv, THIS_MODULE, KBUILD_MODNAME);
+        __xenbus_register_backend(drv, THIS_MODULE, KBUILD_MODNAME)
 
 void xenbus_unregister_driver(struct xenbus_driver *drv);