8 files changed, 116 insertions, 29 deletions

diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 2140398a2a8c..2ccd3592d41f 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -2,7 +2,7 @@ ifeq ($(filter y, $(CONFIG_ARM) $(CONFIG_ARM64)),)
 obj-$(CONFIG_HOTPLUG_CPU)               += cpu_hotplug.o
 endif
 obj-$(CONFIG_X86)                       += fallback.o
-obj-y   += grant-table.o features.o balloon.o manage.o
+obj-y   += grant-table.o features.o balloon.o manage.o preempt.o
 obj-y   += events/
 obj-y   += xenbus/
 
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/preempt.c b/drivers/xen/preempt.c
new file mode 100644
index 000000000000..a1800c150839
--- /dev/null
+++ b/drivers/xen/preempt.c
@@ -0,0 +1,44 @@
+/*
+ * Preemptible hypercalls
+ *
+ * Copyright (C) 2014 Citrix Systems R&D ltd.
+ *
+ * This source code is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ */
+
+#include <linux/sched.h>
+#include <xen/xen-ops.h>
+
+#ifndef CONFIG_PREEMPT
+
+/*
+ * Some hypercalls issued by the toolstack can take many 10s of
+ * seconds. Allow tasks running hypercalls via the privcmd driver to
+ * be voluntarily preempted even if full kernel preemption is
+ * disabled.
+ *
+ * Such preemptible hypercalls are bracketed by
+ * xen_preemptible_hcall_begin() and xen_preemptible_hcall_end()
+ * calls.
+ */
+
+DEFINE_PER_CPU(bool, xen_in_preemptible_hcall);
+EXPORT_SYMBOL_GPL(xen_in_preemptible_hcall);
+
+asmlinkage __visible void xen_maybe_preempt_hcall(void)
+{
+        if (unlikely(__this_cpu_read(xen_in_preemptible_hcall)
+                     && should_resched())) {
+                /*
+                 * Clear flag as we may be rescheduled on a different
+                 * cpu.
+                 */
+                __this_cpu_write(xen_in_preemptible_hcall, false);
+                _cond_resched();
+                __this_cpu_write(xen_in_preemptible_hcall, true);
+        }
+}
+#endif /* CONFIG_PREEMPT */
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 569a13b9e856..59ac71c4a043 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -56,10 +56,12 @@ static long privcmd_ioctl_hypercall(void __user *udata)
         if (copy_from_user(&hypercall, udata, sizeof(hypercall)))
                 return -EFAULT;
 
+        xen_preemptible_hcall_begin();
         ret = privcmd_call(hypercall.op,
                            hypercall.arg[0], hypercall.arg[1],
                            hypercall.arg[2], hypercall.arg[3],
                            hypercall.arg[4]);
+        xen_preemptible_hcall_end();
 
         return ret;
 }
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/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index 61653a03a8f5..9faca6a60bb0 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -709,12 +709,11 @@ static int prepare_pending_reqs(struct vscsibk_info *info,
 static int scsiback_do_cmd_fn(struct vscsibk_info *info)
 {
         struct vscsiif_back_ring *ring = &info->ring;
-        struct vscsiif_request *ring_req;
+        struct vscsiif_request ring_req;
         struct vscsibk_pend *pending_req;
         RING_IDX rc, rp;
         int err, more_to_do;
         uint32_t result;
-        uint8_t act;
 
         rc = ring->req_cons;
         rp = ring->sring->req_prod;
@@ -735,11 +734,10 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info)
                 if (!pending_req)
                         return 1;
 
-                ring_req = RING_GET_REQUEST(ring, rc);
+                ring_req = *RING_GET_REQUEST(ring, rc);
                 ring->req_cons = ++rc;
 
-                act = ring_req->act;
-                err = prepare_pending_reqs(info, ring_req, pending_req);
+                err = prepare_pending_reqs(info, &ring_req, pending_req);
                 if (err) {
                         switch (err) {
                         case -ENODEV:
@@ -755,9 +753,9 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info)
                         return 1;
                 }
 
-                switch (act) {
+                switch (ring_req.act) {
                 case VSCSIIF_ACT_SCSI_CDB:
-                        if (scsiback_gnttab_data_map(ring_req, pending_req)) {
+                        if (scsiback_gnttab_data_map(&ring_req, pending_req)) {
                                 scsiback_fast_flush_area(pending_req);
                                 scsiback_do_resp_with_sense(NULL,
                                         DRIVER_ERROR << 24, 0, pending_req);
@@ -768,7 +766,7 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info)
                         break;
                 case VSCSIIF_ACT_SCSI_ABORT:
                         scsiback_device_action(pending_req, TMR_ABORT_TASK,
-                                ring_req->ref_rqid);
+                                ring_req.ref_rqid);
                         break;
                 case VSCSIIF_ACT_SCSI_RESET:
                         scsiback_device_action(pending_req, TMR_LUN_RESET, 0);