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>

1 files changed, 181 insertions, 0 deletions

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);