xen/pciback: xen pci backend driver.

This is the host side counterpart to the frontend driver in
drivers/pci/xen-pcifront.c. The PV protocol is also implemented by
frontend drivers in other OSes too, such as the BSDs.

The PV protocol is rather simple. There is page shared with the guest,
which has the 'struct xen_pci_sharedinfo' embossed in it. The backend
has a thread that is kicked every-time the structure is changed and
based on the operation field it performs specific tasks:

 XEN_PCI_OP_conf_[read|write]:
   Read/Write 0xCF8/0xCFC filtered data. (conf_space*.c)
   Based on which field is probed, we either enable/disable the PCI
   device, change power state, read VPD, etc. The major goal of this
   call is to provide a Physical IRQ (PIRQ) to the guest.

   The PIRQ is Xen hypervisor global IRQ value irrespective of the IRQ
   is tied in to the IO-APIC, or is a vector. For GSI type
   interrupts, the PIRQ==GSI holds. For MSI/MSI-X the
   PIRQ value != Linux IRQ number (thought PIRQ==vector).

   Please note, that with Xen, all interrupts (except those level shared ones)
   are injected directly to the guest - there is no host interaction.

 XEN_PCI_OP_[enable|disable]_msi[|x] (pciback_ops.c)
   Enables/disables the MSI/MSI-X capability of the device. These operations
   setup the MSI/MSI-X vectors for the guest and pass them to the frontend.

   When the device is activated, the interrupts are directly injected in the
   guest without involving the host.

 XEN_PCI_OP_aer_[detected|resume|mmio|slotreset]: In case of failure,
  perform the appropriate AER commands on the guest. Right now that is
  a cop-out - we just kill the guest.

Besides implementing those commands, it can also

 - hide a PCI device from the host. When booting up, the user can specify
   xen-pciback.hide=(1:0:0)(BDF..) so that host does not try to use the
   device.

The driver was lifted from linux-2.6.18.hg tree and fixed up
so that it could compile under v3.0. Per suggestion from Jesse Barnes
moved the driver to drivers/xen/xen-pciback.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

1 files changed, 318 insertions, 0 deletions

diff --git a/drivers/xen/xen-pciback/conf_space_header.c b/drivers/xen/xen-pciback/conf_space_header.c
new file mode 100644
index 000000000000..3ae7da137f7e
--- /dev/null
+++ b/drivers/xen/xen-pciback/conf_space_header.c
@@ -0,0 +1,318 @@
+/*
+ * PCI Backend - Handles the virtual fields in the configuration space headers.
+ *
+ * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
+ */
+
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include "pciback.h"
+#include "conf_space.h"
+
+struct pci_bar_info {
+        u32 val;
+        u32 len_val;
+        int which;
+};
+
+#define is_enable_cmd(value) ((value)&(PCI_COMMAND_MEMORY|PCI_COMMAND_IO))
+#define is_master_cmd(value) ((value)&PCI_COMMAND_MASTER)
+
+static int command_write(struct pci_dev *dev, int offset, u16 value, void *data)
+{
+        int err;
+
+        if (!pci_is_enabled(dev) && is_enable_cmd(value)) {
+                if (unlikely(verbose_request))
+                        printk(KERN_DEBUG "pciback: %s: enable\n",
+                               pci_name(dev));
+                err = pci_enable_device(dev);
+                if (err)
+                        return err;
+        } else if (pci_is_enabled(dev) && !is_enable_cmd(value)) {
+                if (unlikely(verbose_request))
+                        printk(KERN_DEBUG "pciback: %s: disable\n",
+                               pci_name(dev));
+                pci_disable_device(dev);
+        }
+
+        if (!dev->is_busmaster && is_master_cmd(value)) {
+                if (unlikely(verbose_request))
+                        printk(KERN_DEBUG "pciback: %s: set bus master\n",
+                               pci_name(dev));
+                pci_set_master(dev);
+        }
+
+        if (value & PCI_COMMAND_INVALIDATE) {
+                if (unlikely(verbose_request))
+                        printk(KERN_DEBUG
+                               "pciback: %s: enable memory-write-invalidate\n",
+                               pci_name(dev));
+                err = pci_set_mwi(dev);
+                if (err) {
+                        printk(KERN_WARNING
+                               "pciback: %s: cannot enable "
+                               "memory-write-invalidate (%d)\n",
+                               pci_name(dev), err);
+                        value &= ~PCI_COMMAND_INVALIDATE;
+                }
+        }
+
+        return pci_write_config_word(dev, offset, value);
+}
+
+static int rom_write(struct pci_dev *dev, int offset, u32 value, void *data)
+{
+        struct pci_bar_info *bar = data;
+
+        if (unlikely(!bar)) {
+                printk(KERN_WARNING "pciback: driver data not found for %s\n",
+                       pci_name(dev));
+                return XEN_PCI_ERR_op_failed;
+        }
+
+        /* A write to obtain the length must happen as a 32-bit write.
+         * This does not (yet) support writing individual bytes
+         */
+        if (value == ~PCI_ROM_ADDRESS_ENABLE)
+                bar->which = 1;
+        else {
+                u32 tmpval;
+                pci_read_config_dword(dev, offset, &tmpval);
+                if (tmpval != bar->val && value == bar->val) {
+                        /* Allow restoration of bar value. */
+                        pci_write_config_dword(dev, offset, bar->val);
+                }
+                bar->which = 0;
+        }
+
+        /* Do we need to support enabling/disabling the rom address here? */
+
+        return 0;
+}
+
+/* For the BARs, only allow writes which write ~0 or
+ * the correct resource information
+ * (Needed for when the driver probes the resource usage)
+ */
+static int bar_write(struct pci_dev *dev, int offset, u32 value, void *data)
+{
+        struct pci_bar_info *bar = data;
+
+        if (unlikely(!bar)) {
+                printk(KERN_WARNING "pciback: driver data not found for %s\n",
+                       pci_name(dev));
+                return XEN_PCI_ERR_op_failed;
+        }
+
+        /* A write to obtain the length must happen as a 32-bit write.
+         * This does not (yet) support writing individual bytes
+         */
+        if (value == ~0)
+                bar->which = 1;
+        else {
+                u32 tmpval;
+                pci_read_config_dword(dev, offset, &tmpval);
+                if (tmpval != bar->val && value == bar->val) {
+                        /* Allow restoration of bar value. */
+                        pci_write_config_dword(dev, offset, bar->val);
+                }
+                bar->which = 0;
+        }
+
+        return 0;
+}
+
+static int bar_read(struct pci_dev *dev, int offset, u32 * value, void *data)
+{
+        struct pci_bar_info *bar = data;
+
+        if (unlikely(!bar)) {
+                printk(KERN_WARNING "pciback: driver data not found for %s\n",
+                       pci_name(dev));
+                return XEN_PCI_ERR_op_failed;
+        }
+
+        *value = bar->which ? bar->len_val : bar->val;
+
+        return 0;
+}
+
+static inline void read_dev_bar(struct pci_dev *dev,
+                                struct pci_bar_info *bar_info, int offset,
+                                u32 len_mask)
+{
+        pci_read_config_dword(dev, offset, &bar_info->val);
+        pci_write_config_dword(dev, offset, len_mask);
+        pci_read_config_dword(dev, offset, &bar_info->len_val);
+        pci_write_config_dword(dev, offset, bar_info->val);
+}
+
+static void *bar_init(struct pci_dev *dev, int offset)
+{
+        struct pci_bar_info *bar = kmalloc(sizeof(*bar), GFP_KERNEL);
+
+        if (!bar)
+                return ERR_PTR(-ENOMEM);
+
+        read_dev_bar(dev, bar, offset, ~0);
+        bar->which = 0;
+
+        return bar;
+}
+
+static void *rom_init(struct pci_dev *dev, int offset)
+{
+        struct pci_bar_info *bar = kmalloc(sizeof(*bar), GFP_KERNEL);
+
+        if (!bar)
+                return ERR_PTR(-ENOMEM);
+
+        read_dev_bar(dev, bar, offset, ~PCI_ROM_ADDRESS_ENABLE);
+        bar->which = 0;
+
+        return bar;
+}
+
+static void bar_reset(struct pci_dev *dev, int offset, void *data)
+{
+        struct pci_bar_info *bar = data;
+
+        bar->which = 0;
+}
+
+static void bar_release(struct pci_dev *dev, int offset, void *data)
+{
+        kfree(data);
+}
+
+static int interrupt_read(struct pci_dev *dev, int offset, u8 * value,
+                          void *data)
+{
+        *value = (u8) dev->irq;
+
+        return 0;
+}
+
+static int bist_write(struct pci_dev *dev, int offset, u8 value, void *data)
+{
+        u8 cur_value;
+        int err;
+
+        err = pci_read_config_byte(dev, offset, &cur_value);
+        if (err)
+                goto out;
+
+        if ((cur_value & ~PCI_BIST_START) == (value & ~PCI_BIST_START)
+            || value == PCI_BIST_START)
+                err = pci_write_config_byte(dev, offset, value);
+
+out:
+        return err;
+}
+
+static const struct config_field header_common[] = {
+        {
+         .offset    = PCI_COMMAND,
+         .size      = 2,
+         .u.w.read  = pciback_read_config_word,
+         .u.w.write = command_write,
+        },
+        {
+         .offset    = PCI_INTERRUPT_LINE,
+         .size      = 1,
+         .u.b.read  = interrupt_read,
+        },
+        {
+         .offset    = PCI_INTERRUPT_PIN,
+         .size      = 1,
+         .u.b.read  = pciback_read_config_byte,
+        },
+        {
+         /* Any side effects of letting driver domain control cache line? */
+         .offset    = PCI_CACHE_LINE_SIZE,
+         .size      = 1,
+         .u.b.read  = pciback_read_config_byte,
+         .u.b.write = pciback_write_config_byte,
+        },
+        {
+         .offset    = PCI_LATENCY_TIMER,
+         .size      = 1,
+         .u.b.read  = pciback_read_config_byte,
+        },
+        {
+         .offset    = PCI_BIST,
+         .size      = 1,
+         .u.b.read  = pciback_read_config_byte,
+         .u.b.write = bist_write,
+        },
+        {}
+};
+
+#define CFG_FIELD_BAR(reg_offset)                       \
+        {                                               \
+         .offset     = reg_offset,                      \
+         .size       = 4,                               \
+         .init       = bar_init,                        \
+         .reset      = bar_reset,                       \
+         .release    = bar_release,                     \
+         .u.dw.read  = bar_read,                        \
+         .u.dw.write = bar_write,                       \
+         }
+
+#define CFG_FIELD_ROM(reg_offset)                       \
+        {                                               \
+         .offset     = reg_offset,                      \
+         .size       = 4,                               \
+         .init       = rom_init,                        \
+         .reset      = bar_reset,                       \
+         .release    = bar_release,                     \
+         .u.dw.read  = bar_read,                        \
+         .u.dw.write = rom_write,                       \
+         }
+
+static const struct config_field header_0[] = {
+        CFG_FIELD_BAR(PCI_BASE_ADDRESS_0),
+        CFG_FIELD_BAR(PCI_BASE_ADDRESS_1),
+        CFG_FIELD_BAR(PCI_BASE_ADDRESS_2),
+        CFG_FIELD_BAR(PCI_BASE_ADDRESS_3),
+        CFG_FIELD_BAR(PCI_BASE_ADDRESS_4),
+        CFG_FIELD_BAR(PCI_BASE_ADDRESS_5),
+        CFG_FIELD_ROM(PCI_ROM_ADDRESS),
+        {}
+};
+
+static const struct config_field header_1[] = {
+        CFG_FIELD_BAR(PCI_BASE_ADDRESS_0),
+        CFG_FIELD_BAR(PCI_BASE_ADDRESS_1),
+        CFG_FIELD_ROM(PCI_ROM_ADDRESS1),
+        {}
+};
+
+int pciback_config_header_add_fields(struct pci_dev *dev)
+{
+        int err;
+
+        err = pciback_config_add_fields(dev, header_common);
+        if (err)
+                goto out;
+
+        switch (dev->hdr_type) {
+        case PCI_HEADER_TYPE_NORMAL:
+                err = pciback_config_add_fields(dev, header_0);
+                break;
+
+        case PCI_HEADER_TYPE_BRIDGE:
+                err = pciback_config_add_fields(dev, header_1);
+                break;
+
+        default:
+                err = -EINVAL;
+                printk(KERN_ERR "pciback: %s: Unsupported header type %d!\n",
+                       pci_name(dev), dev->hdr_type);
+                break;
+        }
+
+out:
+        return err;
+}