xen: Xen PCI platform device driver.

Add the xen pci platform device driver that is responsible
for initializing the grant table and xenbus in PV on HVM mode.
Few changes to xenbus and grant table are necessary to allow the delayed
initialization in HVM mode.
Grant table needs few additional modifications to work in HVM mode.

The Xen PCI platform device raises an irq every time an event has been
delivered to us. However these interrupts are only delivered to vcpu 0.
The Xen PCI platform interrupt handler calls xen_hvm_evtchn_do_upcall
that is a little wrapper around __xen_evtchn_do_upcall, the traditional
Xen upcall handler, the very same used with traditional PV guests.

When running on HVM the event channel upcall is never called while in
progress because it is a normal Linux irq handler (and we cannot switch
the irq chip wholesale to the Xen PV ones as we are running QEMU and
might have passed in PCI devices), therefore we cannot be sure that
evtchn_upcall_pending is 0 when returning.
For this reason if evtchn_upcall_pending is set by Xen we need to loop
again on the event channels set pending otherwise we might loose some
event channel deliveries.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

7 files changed, 283 insertions, 18 deletions

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index fad3df2c1276..8f84b108b491 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -62,4 +62,13 @@ config XEN_SYS_HYPERVISOR
          virtual environment, /sys/hypervisor will still be present,
          but will have no xen contents.
 
+config XEN_PLATFORM_PCI
+        tristate "xen platform pci device driver"
+        depends on XEN
+        default m
+        help
+          Driver for the Xen PCI Platform device: it is responsible for
+          initializing xenbus and grant_table when running in a Xen HVM
+          domain. As a consequence this driver is required to run any Xen PV
+          frontend on Xen HVM.
 endmenu
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 7c284342f30f..e392fb776af3 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -9,4 +9,5 @@ obj-$(CONFIG_XEN_XENCOMM)	+= xencomm.o
 obj-$(CONFIG_XEN_BALLOON)       += balloon.o
 obj-$(CONFIG_XEN_DEV_EVTCHN)    += evtchn.o
 obj-$(CONFIG_XENFS)             += xenfs/
-obj-$(CONFIG_XEN_SYS_HYPERVISOR)        += sys-hypervisor.o
\ No newline at end of file
+obj-$(CONFIG_XEN_SYS_HYPERVISOR)        += sys-hypervisor.o
+obj-$(CONFIG_XEN_PLATFORM_PCI)  += platform-pci.o
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index d659480125f0..7c64473c9f3f 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -665,7 +665,7 @@ static void __xen_evtchn_do_upcall(void)
 
                 count = __get_cpu_var(xed_nesting_count);
                 __get_cpu_var(xed_nesting_count) = 0;
-        } while(count != 1);
+        } while (count != 1 || vcpu_info->evtchn_upcall_pending);
 
 out:
 
@@ -689,6 +689,7 @@ void xen_hvm_evtchn_do_upcall(void)
 {
         __xen_evtchn_do_upcall();
 }
+EXPORT_SYMBOL_GPL(xen_hvm_evtchn_do_upcall);
 
 /* Rebind a new event channel to an existing irq. */
 void rebind_evtchn_irq(int evtchn, int irq)
@@ -725,7 +726,10 @@ static int rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
         struct evtchn_bind_vcpu bind_vcpu;
         int evtchn = evtchn_from_irq(irq);
 
-        if (!VALID_EVTCHN(evtchn))
+        /* events delivered via platform PCI interrupts are always
+         * routed to vcpu 0 */
+        if (!VALID_EVTCHN(evtchn) ||
+                (xen_hvm_domain() && !xen_have_vector_callback))
                 return -1;
 
         /* Send future instances of this interrupt to other vcpu. */
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index f66db3b91d61..6c4531816496 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -37,11 +37,13 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/uaccess.h>
+#include <linux/io.h>
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
 #include <xen/page.h>
 #include <xen/grant_table.h>
+#include <xen/interface/memory.h>
 #include <asm/xen/hypercall.h>
 
 #include <asm/pgtable.h>
@@ -59,6 +61,8 @@ static unsigned int boot_max_nr_grant_frames;
 static int gnttab_free_count;
 static grant_ref_t gnttab_free_head;
 static DEFINE_SPINLOCK(gnttab_list_lock);
+unsigned long xen_hvm_resume_frames;
+EXPORT_SYMBOL_GPL(xen_hvm_resume_frames);
 
 static struct grant_entry *shared;
 
@@ -433,7 +437,7 @@ static unsigned int __max_nr_grant_frames(void)
         return query.max_nr_frames;
 }
 
-static inline unsigned int max_nr_grant_frames(void)
+unsigned int gnttab_max_grant_frames(void)
 {
         unsigned int xen_max = __max_nr_grant_frames();
 
@@ -441,6 +445,7 @@ static inline unsigned int max_nr_grant_frames(void)
                 return boot_max_nr_grant_frames;
         return xen_max;
 }
+EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 
 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 {
@@ -449,6 +454,30 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
         unsigned int nr_gframes = end_idx + 1;
         int rc;
 
+        if (xen_hvm_domain()) {
+                struct xen_add_to_physmap xatp;
+                unsigned int i = end_idx;
+                rc = 0;
+                /*
+                 * Loop backwards, so that the first hypercall has the largest
+                 * index, ensuring that the table will grow only once.
+                 */
+                do {
+                        xatp.domid = DOMID_SELF;
+                        xatp.idx = i;
+                        xatp.space = XENMAPSPACE_grant_table;
+                        xatp.gpfn = (xen_hvm_resume_frames >> PAGE_SHIFT) + i;
+                        rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
+                        if (rc != 0) {
+                                printk(KERN_WARNING
+                                                "grant table add_to_physmap failed, err=%d\n", rc);
+                                break;
+                        }
+                } while (i-- > start_idx);
+
+                return rc;
+        }
+
         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
         if (!frames)
                 return -ENOMEM;
@@ -465,7 +494,7 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 
         BUG_ON(rc || setup.status);
 
-        rc = arch_gnttab_map_shared(frames, nr_gframes, max_nr_grant_frames(),
+        rc = arch_gnttab_map_shared(frames, nr_gframes, gnttab_max_grant_frames(),
                                     &shared);
         BUG_ON(rc);
 
@@ -476,9 +505,27 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 
 int gnttab_resume(void)
 {
-        if (max_nr_grant_frames() < nr_grant_frames)
+        unsigned int max_nr_gframes;
+
+        max_nr_gframes = gnttab_max_grant_frames();
+        if (max_nr_gframes < nr_grant_frames)
                 return -ENOSYS;
-        return gnttab_map(0, nr_grant_frames - 1);
+
+        if (xen_pv_domain())
+                return gnttab_map(0, nr_grant_frames - 1);
+
+        if (!shared) {
+                shared = ioremap(xen_hvm_resume_frames, PAGE_SIZE * max_nr_gframes);
+                if (shared == NULL) {
+                        printk(KERN_WARNING
+                                        "Failed to ioremap gnttab share frames!");
+                        return -ENOMEM;
+                }
+        }
+
+        gnttab_map(0, nr_grant_frames - 1);
+
+        return 0;
 }
 
 int gnttab_suspend(void)
@@ -495,7 +542,7 @@ static int gnttab_expand(unsigned int req_entries)
         cur = nr_grant_frames;
         extra = ((req_entries + (GREFS_PER_GRANT_FRAME-1)) /
                  GREFS_PER_GRANT_FRAME);
-        if (cur + extra > max_nr_grant_frames())
+        if (cur + extra > gnttab_max_grant_frames())
                 return -ENOSPC;
 
         rc = gnttab_map(cur, cur + extra - 1);
@@ -505,15 +552,12 @@ static int gnttab_expand(unsigned int req_entries)
         return rc;
 }
 
-static int __devinit gnttab_init(void)
+int gnttab_init(void)
 {
         int i;
         unsigned int max_nr_glist_frames, nr_glist_frames;
         unsigned int nr_init_grefs;
 
-        if (!xen_domain())
-                return -ENODEV;
-
         nr_grant_frames = 1;
         boot_max_nr_grant_frames = __max_nr_grant_frames();
 
@@ -556,5 +600,18 @@ static int __devinit gnttab_init(void)
         kfree(gnttab_list);
         return -ENOMEM;
 }
+EXPORT_SYMBOL_GPL(gnttab_init);
+
+static int __devinit __gnttab_init(void)
+{
+        /* Delay grant-table initialization in the PV on HVM case */
+        if (xen_hvm_domain())
+                return 0;
+
+        if (!xen_pv_domain())
+                return -ENODEV;
+
+        return gnttab_init();
+}
 
-core_initcall(gnttab_init);
+core_initcall(__gnttab_init);
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 07e857b0de13..af9c5594d315 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -264,5 +264,6 @@ static int __init setup_shutdown_event(void)
 
         return 0;
 }
+EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);
 
 subsys_initcall(setup_shutdown_event);
diff --git a/drivers/xen/platform-pci.c b/drivers/xen/platform-pci.c
new file mode 100644
index 000000000000..a0ee5d06f715
--- /dev/null
+++ b/drivers/xen/platform-pci.c
@@ -0,0 +1,181 @@
+/******************************************************************************
+ * platform-pci.c
+ *
+ * Xen platform PCI device driver
+ * Copyright (c) 2005, Intel Corporation.
+ * Copyright (c) 2007, XenSource Inc.
+ * Copyright (c) 2010, Citrix
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ */
+
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+
+#include <xen/grant_table.h>
+#include <xen/xenbus.h>
+#include <xen/events.h>
+#include <xen/hvm.h>
+
+#define DRV_NAME    "xen-platform-pci"
+
+MODULE_AUTHOR("ssmith@xensource.com and stefano.stabellini@eu.citrix.com");
+MODULE_DESCRIPTION("Xen platform PCI device");
+MODULE_LICENSE("GPL");
+
+static unsigned long platform_mmio;
+static unsigned long platform_mmio_alloc;
+static unsigned long platform_mmiolen;
+
+unsigned long alloc_xen_mmio(unsigned long len)
+{
+        unsigned long addr;
+
+        addr = platform_mmio + platform_mmio_alloc;
+        platform_mmio_alloc += len;
+        BUG_ON(platform_mmio_alloc > platform_mmiolen);
+
+        return addr;
+}
+
+static uint64_t get_callback_via(struct pci_dev *pdev)
+{
+        u8 pin;
+        int irq;
+
+        irq = pdev->irq;
+        if (irq < 16)
+                return irq; /* ISA IRQ */
+
+        pin = pdev->pin;
+
+        /* We don't know the GSI. Specify the PCI INTx line instead. */
+        return ((uint64_t)0x01 << 56) | /* PCI INTx identifier */
+                ((uint64_t)pci_domain_nr(pdev->bus) << 32) |
+                ((uint64_t)pdev->bus->number << 16) |
+                ((uint64_t)(pdev->devfn & 0xff) << 8) |
+                ((uint64_t)(pin - 1) & 3);
+}
+
+static irqreturn_t do_hvm_evtchn_intr(int irq, void *dev_id)
+{
+        xen_hvm_evtchn_do_upcall();
+        return IRQ_HANDLED;
+}
+
+static int xen_allocate_irq(struct pci_dev *pdev)
+{
+        return request_irq(pdev->irq, do_hvm_evtchn_intr,
+                        IRQF_DISABLED | IRQF_NOBALANCING | IRQF_TRIGGER_RISING,
+                        "xen-platform-pci", pdev);
+}
+
+static int __devinit platform_pci_init(struct pci_dev *pdev,
+                                       const struct pci_device_id *ent)
+{
+        int i, ret;
+        long ioaddr, iolen;
+        long mmio_addr, mmio_len;
+        uint64_t callback_via;
+        unsigned int max_nr_gframes;
+
+        i = pci_enable_device(pdev);
+        if (i)
+                return i;
+
+        ioaddr = pci_resource_start(pdev, 0);
+        iolen = pci_resource_len(pdev, 0);
+
+        mmio_addr = pci_resource_start(pdev, 1);
+        mmio_len = pci_resource_len(pdev, 1);
+
+        if (mmio_addr == 0 || ioaddr == 0) {
+                dev_err(&pdev->dev, "no resources found\n");
+                ret = -ENOENT;
+                goto pci_out;
+        }
+
+        if (request_mem_region(mmio_addr, mmio_len, DRV_NAME) == NULL) {
+                dev_err(&pdev->dev, "MEM I/O resource 0x%lx @ 0x%lx busy\n",
+                       mmio_addr, mmio_len);
+                ret = -EBUSY;
+                goto pci_out;
+        }
+
+        if (request_region(ioaddr, iolen, DRV_NAME) == NULL) {
+                dev_err(&pdev->dev, "I/O resource 0x%lx @ 0x%lx busy\n",
+                       iolen, ioaddr);
+                ret = -EBUSY;
+                goto mem_out;
+        }
+
+        platform_mmio = mmio_addr;
+        platform_mmiolen = mmio_len;
+
+        if (!xen_have_vector_callback) {
+                ret = xen_allocate_irq(pdev);
+                if (ret) {
+                        dev_warn(&pdev->dev, "request_irq failed err=%d\n", ret);
+                        goto out;
+                }
+                callback_via = get_callback_via(pdev);
+                ret = xen_set_callback_via(callback_via);
+                if (ret) {
+                        dev_warn(&pdev->dev, "Unable to set the evtchn callback "
+                                         "err=%d\n", ret);
+                        goto out;
+                }
+        }
+
+        max_nr_gframes = gnttab_max_grant_frames();
+        xen_hvm_resume_frames = alloc_xen_mmio(PAGE_SIZE * max_nr_gframes);
+        ret = gnttab_init();
+        if (ret)
+                goto out;
+        xenbus_probe(NULL);
+        return 0;
+
+out:
+        release_region(ioaddr, iolen);
+mem_out:
+        release_mem_region(mmio_addr, mmio_len);
+pci_out:
+        pci_disable_device(pdev);
+        return ret;
+}
+
+static struct pci_device_id platform_pci_tbl[] __devinitdata = {
+        {PCI_VENDOR_ID_XEN, PCI_DEVICE_ID_XEN_PLATFORM,
+                PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
+        {0,}
+};
+
+MODULE_DEVICE_TABLE(pci, platform_pci_tbl);
+
+static struct pci_driver platform_driver = {
+        .name =           DRV_NAME,
+        .probe =          platform_pci_init,
+        .id_table =       platform_pci_tbl,
+};
+
+static int __init platform_pci_module_init(void)
+{
+        return pci_register_driver(&platform_driver);
+}
+
+module_init(platform_pci_module_init);
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index d96fa75b45ec..a9e83c438cbb 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -781,8 +781,23 @@ void xenbus_probe(struct work_struct *unused)
         /* Notify others that xenstore is up */
         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 }
+EXPORT_SYMBOL_GPL(xenbus_probe);
 
-static int __init xenbus_probe_init(void)
+static int __init xenbus_probe_initcall(void)
+{
+        if (!xen_domain())
+                return -ENODEV;
+
+        if (xen_initial_domain() || xen_hvm_domain())
+                return 0;
+
+        xenbus_probe(NULL);
+        return 0;
+}
+
+device_initcall(xenbus_probe_initcall);
+
+static int __init xenbus_init(void)
 {
         int err = 0;
 
@@ -834,9 +849,6 @@ static int __init xenbus_probe_init(void)
                 goto out_unreg_back;
         }
 
-        if (!xen_initial_domain())
-                xenbus_probe(NULL);
-
 #ifdef CONFIG_XEN_COMPAT_XENFS
         /*
          * Create xenfs mountpoint in /proc for compatibility with
@@ -857,7 +869,7 @@ static int __init xenbus_probe_init(void)
         return err;
 }
 
-postcore_initcall(xenbus_probe_init);
+postcore_initcall(xenbus_init);
 
 MODULE_LICENSE("GPL");