1 files changed, 153 insertions, 20 deletions

diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index c1c1544b8485..ac4453d8520e 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -56,6 +56,9 @@
 #include <linux/virtio_console.h>
 #include <linux/pm.h>
 #include <linux/export.h>
+#include <linux/pci.h>
+#include <linux/virtio_pci.h>
+#include <asm/acpi.h>
 #include <asm/apic.h>
 #include <asm/lguest.h>
 #include <asm/paravirt.h>
@@ -71,6 +74,8 @@
 #include <asm/stackprotector.h>
 #include <asm/reboot.h>         /* for struct machine_ops */
 #include <asm/kvm_para.h>
+#include <asm/pci_x86.h>
+#include <asm/pci-direct.h>
 
 /*G:010
  * Welcome to the Guest!
@@ -831,6 +836,24 @@ static struct irq_chip lguest_irq_controller = {
         .irq_unmask     = enable_lguest_irq,
 };
 
+static int lguest_enable_irq(struct pci_dev *dev)
+{
+        u8 line = 0;
+
+        /* We literally use the PCI interrupt line as the irq number. */
+        pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &line);
+        irq_set_chip_and_handler_name(line, &lguest_irq_controller,
+                                      handle_level_irq, "level");
+        dev->irq = line;
+        return 0;
+}
+
+/* We don't do hotplug PCI, so this shouldn't be called. */
+static void lguest_disable_irq(struct pci_dev *dev)
+{
+        WARN_ON(1);
+}
+
 /*
  * This sets up the Interrupt Descriptor Table (IDT) entry for each hardware
  * interrupt (except 128, which is used for system calls), and then tells the
@@ -1181,25 +1204,136 @@ static __init char *lguest_memory_setup(void)
         return "LGUEST";
 }
 
+/* Offset within PCI config space of BAR access capability. */
+static int console_cfg_offset = 0;
+static int console_access_cap;
+
+/* Set up so that we access off in bar0 (on bus 0, device 1, function 0) */
+static void set_cfg_window(u32 cfg_offset, u32 off)
+{
+        write_pci_config_byte(0, 1, 0,
+                              cfg_offset + offsetof(struct virtio_pci_cap, bar),
+                              0);
+        write_pci_config(0, 1, 0,
+                         cfg_offset + offsetof(struct virtio_pci_cap, length),
+                         4);
+        write_pci_config(0, 1, 0,
+                         cfg_offset + offsetof(struct virtio_pci_cap, offset),
+                         off);
+}
+
+static void write_bar_via_cfg(u32 cfg_offset, u32 off, u32 val)
+{
+        /*
+         * We could set this up once, then leave it; nothing else in the *
+         * kernel should touch these registers.  But if it went wrong, that
+         * would be a horrible bug to find.
+         */
+        set_cfg_window(cfg_offset, off);
+        write_pci_config(0, 1, 0,
+                         cfg_offset + sizeof(struct virtio_pci_cap), val);
+}
+
+static void probe_pci_console(void)
+{
+        u8 cap, common_cap = 0, device_cap = 0;
+        /* Offset within BAR0 */
+        u32 device_offset;
+        u32 device_len;
+
+        /* Avoid recursive printk into here. */
+        console_cfg_offset = -1;
+
+        if (!early_pci_allowed()) {
+                printk(KERN_ERR "lguest: early PCI access not allowed!\n");
+                return;
+        }
+
+        /* We expect a console PCI device at BUS0, slot 1. */
+        if (read_pci_config(0, 1, 0, 0) != 0x10431AF4) {
+                printk(KERN_ERR "lguest: PCI device is %#x!\n",
+                       read_pci_config(0, 1, 0, 0));
+                return;
+        }
+
+        /* Find the capabilities we need (must be in bar0) */
+        cap = read_pci_config_byte(0, 1, 0, PCI_CAPABILITY_LIST);
+        while (cap) {
+                u8 vndr = read_pci_config_byte(0, 1, 0, cap);
+                if (vndr == PCI_CAP_ID_VNDR) {
+                        u8 type, bar;
+                        u32 offset, length;
+
+                        type = read_pci_config_byte(0, 1, 0,
+                            cap + offsetof(struct virtio_pci_cap, cfg_type));
+                        bar = read_pci_config_byte(0, 1, 0,
+                            cap + offsetof(struct virtio_pci_cap, bar));
+                        offset = read_pci_config(0, 1, 0,
+                            cap + offsetof(struct virtio_pci_cap, offset));
+                        length = read_pci_config(0, 1, 0,
+                            cap + offsetof(struct virtio_pci_cap, length));
+
+                        switch (type) {
+                        case VIRTIO_PCI_CAP_DEVICE_CFG:
+                                if (bar == 0) {
+                                        device_cap = cap;
+                                        device_offset = offset;
+                                        device_len = length;
+                                }
+                                break;
+                        case VIRTIO_PCI_CAP_PCI_CFG:
+                                console_access_cap = cap;
+                                break;
+                        }
+                }
+                cap = read_pci_config_byte(0, 1, 0, cap + PCI_CAP_LIST_NEXT);
+        }
+        if (!device_cap || !console_access_cap) {
+                printk(KERN_ERR "lguest: No caps (%u/%u/%u) in console!\n",
+                       common_cap, device_cap, console_access_cap);
+                return;
+        }
+
+        /*
+         * Note that we can't check features, until we've set the DRIVER
+         * status bit.  We don't want to do that until we have a real driver,
+         * so we just check that the device-specific config has room for
+         * emerg_wr.  If it doesn't support VIRTIO_CONSOLE_F_EMERG_WRITE
+         * it should ignore the access.
+         */
+        if (device_len < (offsetof(struct virtio_console_config, emerg_wr)
+                          + sizeof(u32))) {
+                printk(KERN_ERR "lguest: console missing emerg_wr field\n");
+                return;
+        }
+
+        console_cfg_offset = device_offset;
+        printk(KERN_INFO "lguest: Console via virtio-pci emerg_wr\n");
+}
+
 /*
  * We will eventually use the virtio console device to produce console output,
- * but before that is set up we use LHCALL_NOTIFY on normal memory to produce
- * console output.
+ * but before that is set up we use the virtio PCI console's backdoor mmio
+ * access and the "emergency" write facility (which is legal even before the
+ * device is configured).
  */
 static __init int early_put_chars(u32 vtermno, const char *buf, int count)
 {
-        char scratch[17];
-        unsigned int len = count;
+        /* If we couldn't find PCI console, forget it. */
+        if (console_cfg_offset < 0)
+                return count;
 
-        /* We use a nul-terminated string, so we make a copy.  Icky, huh? */
-        if (len > sizeof(scratch) - 1)
-                len = sizeof(scratch) - 1;
-        scratch[len] = '\0';
-        memcpy(scratch, buf, len);
-        hcall(LHCALL_NOTIFY, __pa(scratch), 0, 0, 0);
+        if (unlikely(!console_cfg_offset)) {
+                probe_pci_console();
+                if (console_cfg_offset < 0)
+                        return count;
+        }
 
-        /* This routine returns the number of bytes actually written. */
-        return len;
+        write_bar_via_cfg(console_access_cap,
+                          console_cfg_offset
+                          + offsetof(struct virtio_console_config, emerg_wr),
+                          buf[0]);
+        return 1;
 }
 
 /*
@@ -1400,14 +1534,6 @@ __init void lguest_init(void)
         atomic_notifier_chain_register(&panic_notifier_list, &paniced);
 
         /*
-         * The IDE code spends about 3 seconds probing for disks: if we reserve
-         * all the I/O ports up front it can't get them and so doesn't probe.
-         * Other device drivers are similar (but less severe).  This cuts the
-         * kernel boot time on my machine from 4.1 seconds to 0.45 seconds.
-         */
-        paravirt_disable_iospace();
-
-        /*
          * This is messy CPU setup stuff which the native boot code does before
          * start_kernel, so we have to do, too:
          */
@@ -1436,6 +1562,13 @@ __init void lguest_init(void)
         /* Register our very early console. */
         virtio_cons_early_init(early_put_chars);
 
+        /* Don't let ACPI try to control our PCI interrupts. */
+        disable_acpi();
+
+        /* We control them ourselves, by overriding these two hooks. */
+        pcibios_enable_irq = lguest_enable_irq;
+        pcibios_disable_irq = lguest_disable_irq;
+
         /*
          * Last of all, we set the power management poweroff hook to point to
          * the Guest routine to power off, and the reboot hook to our restart