qemu/pci: MSI-X support functions

Add functions implementing MSI-X support. First user will be virtio-pci.
Note that platform must set a flag to declare MSI supported: this
is a safety measure to avoid breaking platforms which should support
MSI-X but currently lack this in the interrupt controller emulation.
For PC this will be set by APIC.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

3 files changed, 435 insertions, 0 deletions

diff --git a/hw/msix.c b/hw/msix.c
new file mode 100644
index 0000000000..4ab6da6809
--- /dev/null
+++ b/hw/msix.c
@@ -0,0 +1,378 @@
+/*
+ * MSI-X device support
+ *
+ * This module includes support for MSI-X in pci devices.
+ *
+ * Author: Michael S. Tsirkin <mst@redhat.com>
+ *
+ *  Copyright (c) 2009, Red Hat Inc, Michael S. Tsirkin (mst@redhat.com)
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "hw.h"
+#include "msix.h"
+#include "pci.h"
+
+/* Declaration from linux/pci_regs.h */
+#define  PCI_CAP_ID_MSIX 0x11 /* MSI-X */
+#define  PCI_MSIX_FLAGS 2     /* Table at lower 11 bits */
+#define  PCI_MSIX_FLAGS_QSIZE	0x7FF
+#define  PCI_MSIX_FLAGS_ENABLE	(1 << 15)
+#define  PCI_MSIX_FLAGS_BIRMASK	(7 << 0)
+
+/* MSI-X capability structure */
+#define MSIX_TABLE_OFFSET 4
+#define MSIX_PBA_OFFSET 8
+#define MSIX_CAP_LENGTH 12
+
+/* MSI enable bit is in byte 1 in FLAGS register */
+#define MSIX_ENABLE_OFFSET (PCI_MSIX_FLAGS + 1)
+#define MSIX_ENABLE_MASK (PCI_MSIX_FLAGS_ENABLE >> 8)
+
+/* MSI-X table format */
+#define MSIX_MSG_ADDR 0
+#define MSIX_MSG_UPPER_ADDR 4
+#define MSIX_MSG_DATA 8
+#define MSIX_VECTOR_CTRL 12
+#define MSIX_ENTRY_SIZE 16
+#define MSIX_VECTOR_MASK 0x1
+
+/* How much space does an MSIX table need. */
+/* The spec requires giving the table structure
+ * a 4K aligned region all by itself. Align it to
+ * target pages so that drivers can do passthrough
+ * on the rest of the region. */
+#define MSIX_PAGE_SIZE TARGET_PAGE_ALIGN(0x1000)
+/* Reserve second half of the page for pending bits */
+#define MSIX_PAGE_PENDING (MSIX_PAGE_SIZE / 2)
+#define MSIX_MAX_ENTRIES 32
+
+
+#ifdef MSIX_DEBUG
+#define DEBUG(fmt, ...)                                       \
+    do {                                                      \
+      fprintf(stderr, "%s: " fmt, __func__ , __VA_ARGS__);    \
+    } while (0)
+#else
+#define DEBUG(fmt, ...) do { } while(0)
+#endif
+
+/* Flag for interrupt controller to declare MSI-X support */
+int msix_supported;
+
+/* Add MSI-X capability to the config space for the device. */
+/* Given a bar and its size, add MSI-X table on top of it
+ * and fill MSI-X capability in the config space.
+ * Original bar size must be a power of 2 or 0.
+ * New bar size is returned. */
+static int msix_add_config(struct PCIDevice *pdev, unsigned short nentries,
+                           unsigned bar_nr, unsigned bar_size)
+{
+    int config_offset;
+    uint8_t *config;
+    uint32_t new_size;
+
+    if (nentries < 1 || nentries > PCI_MSIX_FLAGS_QSIZE + 1)
+        return -EINVAL;
+    if (bar_size > 0x80000000)
+        return -ENOSPC;
+
+    /* Add space for MSI-X structures */
+    if (!bar_size)
+        new_size = MSIX_PAGE_SIZE;
+    else if (bar_size < MSIX_PAGE_SIZE) {
+        bar_size = MSIX_PAGE_SIZE;
+        new_size = MSIX_PAGE_SIZE * 2;
+    } else
+        new_size = bar_size * 2;
+
+    pdev->msix_bar_size = new_size;
+    config_offset = pci_add_capability(pdev, PCI_CAP_ID_MSIX, MSIX_CAP_LENGTH);
+    if (config_offset < 0)
+        return config_offset;
+    config = pdev->config + config_offset;
+
+    pci_set_word(config + PCI_MSIX_FLAGS, nentries - 1);
+    /* Table on top of BAR */
+    pci_set_long(config + MSIX_TABLE_OFFSET, bar_size | bar_nr);
+    /* Pending bits on top of that */
+    pci_set_long(config + MSIX_PBA_OFFSET, (bar_size + MSIX_PAGE_PENDING) |
+                 bar_nr);
+    pdev->msix_cap = config_offset;
+    /* Make flags bit writeable. */
+    pdev->wmask[config_offset + MSIX_ENABLE_OFFSET] |= MSIX_ENABLE_MASK;
+    return 0;
+}
+
+static void msix_free_irq_entries(PCIDevice *dev)
+{
+    int vector;
+
+    for (vector = 0; vector < dev->msix_entries_nr; ++vector)
+        dev->msix_entry_used[vector] = 0;
+}
+
+/* Handle MSI-X capability config write. */
+void msix_write_config(PCIDevice *dev, uint32_t addr,
+                       uint32_t val, int len)
+{
+    unsigned enable_pos = dev->msix_cap + MSIX_ENABLE_OFFSET;
+    if (addr + len <= enable_pos || addr > enable_pos)
+        return;
+
+    if (msix_enabled(dev))
+        qemu_set_irq(dev->irq[0], 0);
+}
+
+static uint32_t msix_mmio_readl(void *opaque, target_phys_addr_t addr)
+{
+    PCIDevice *dev = opaque;
+    unsigned int offset = addr & (MSIX_PAGE_SIZE - 1);
+    void *page = dev->msix_table_page;
+    uint32_t val = 0;
+
+    memcpy(&val, (void *)((char *)page + offset), 4);
+
+    return val;
+}
+
+static uint32_t msix_mmio_read_unallowed(void *opaque, target_phys_addr_t addr)
+{
+    fprintf(stderr, "MSI-X: only dword read is allowed!\n");
+    return 0;
+}
+
+static uint8_t msix_pending_mask(int vector)
+{
+    return 1 << (vector % 8);
+}
+
+static uint8_t *msix_pending_byte(PCIDevice *dev, int vector)
+{
+    return dev->msix_table_page + MSIX_PAGE_PENDING + vector / 8;
+}
+
+static int msix_is_pending(PCIDevice *dev, int vector)
+{
+    return *msix_pending_byte(dev, vector) & msix_pending_mask(vector);
+}
+
+static void msix_set_pending(PCIDevice *dev, int vector)
+{
+    *msix_pending_byte(dev, vector) |= msix_pending_mask(vector);
+}
+
+static void msix_clr_pending(PCIDevice *dev, int vector)
+{
+    *msix_pending_byte(dev, vector) &= ~msix_pending_mask(vector);
+}
+
+static int msix_is_masked(PCIDevice *dev, int vector)
+{
+    unsigned offset = vector * MSIX_ENTRY_SIZE + MSIX_VECTOR_CTRL;
+    return dev->msix_table_page[offset] & MSIX_VECTOR_MASK;
+}
+
+static void msix_mmio_writel(void *opaque, target_phys_addr_t addr,
+                             uint32_t val)
+{
+    PCIDevice *dev = opaque;
+    unsigned int offset = addr & (MSIX_PAGE_SIZE - 1);
+    int vector = offset / MSIX_ENTRY_SIZE;
+    memcpy(dev->msix_table_page + offset, &val, 4);
+    if (!msix_is_masked(dev, vector) && msix_is_pending(dev, vector)) {
+        msix_clr_pending(dev, vector);
+        msix_notify(dev, vector);
+    }
+}
+
+static void msix_mmio_write_unallowed(void *opaque, target_phys_addr_t addr,
+                                      uint32_t val)
+{
+    fprintf(stderr, "MSI-X: only dword write is allowed!\n");
+}
+
+static CPUWriteMemoryFunc *msix_mmio_write[] = {
+    msix_mmio_write_unallowed, msix_mmio_write_unallowed, msix_mmio_writel
+};
+
+static CPUReadMemoryFunc *msix_mmio_read[] = {
+    msix_mmio_read_unallowed, msix_mmio_read_unallowed, msix_mmio_readl
+};
+
+/* Should be called from device's map method. */
+void msix_mmio_map(PCIDevice *d, int region_num,
+                   uint32_t addr, uint32_t size, int type)
+{
+    uint8_t *config = d->config + d->msix_cap;
+    uint32_t table = pci_get_long(config + MSIX_TABLE_OFFSET);
+    uint32_t offset = table & ~(MSIX_PAGE_SIZE - 1);
+    /* TODO: for assigned devices, we'll want to make it possible to map
+     * pending bits separately in case they are in a separate bar. */
+    int table_bir = table & PCI_MSIX_FLAGS_BIRMASK;
+
+    if (table_bir != region_num)
+        return;
+    if (size <= offset)
+        return;
+    cpu_register_physical_memory(addr + offset, size - offset,
+                                 d->msix_mmio_index);
+}
+
+/* Initialize the MSI-X structures. Note: if MSI-X is supported, BAR size is
+ * modified, it should be retrieved with msix_bar_size. */
+int msix_init(struct PCIDevice *dev, unsigned short nentries,
+              unsigned bar_nr, unsigned bar_size)
+{
+    int ret;
+    /* Nothing to do if MSI is not supported by interrupt controller */
+    if (!msix_supported)
+        return -ENOTSUP;
+
+    if (nentries > MSIX_MAX_ENTRIES)
+        return -EINVAL;
+
+    dev->msix_entry_used = qemu_mallocz(MSIX_MAX_ENTRIES *
+                                        sizeof *dev->msix_entry_used);
+
+    dev->msix_table_page = qemu_mallocz(MSIX_PAGE_SIZE);
+
+    dev->msix_mmio_index = cpu_register_io_memory(msix_mmio_read,
+                                                  msix_mmio_write, dev);
+    if (dev->msix_mmio_index == -1) {
+        ret = -EBUSY;
+        goto err_index;
+    }
+
+    dev->msix_entries_nr = nentries;
+    ret = msix_add_config(dev, nentries, bar_nr, bar_size);
+    if (ret)
+        goto err_config;
+
+    dev->cap_present |= QEMU_PCI_CAP_MSIX;
+    return 0;
+
+err_config:
+    cpu_unregister_io_memory(dev->msix_mmio_index);
+err_index:
+    qemu_free(dev->msix_table_page);
+    dev->msix_table_page = NULL;
+    qemu_free(dev->msix_entry_used);
+    dev->msix_entry_used = NULL;
+    return ret;
+}
+
+/* Clean up resources for the device. */
+int msix_uninit(PCIDevice *dev)
+{
+    if (!(dev->cap_present & QEMU_PCI_CAP_MSIX))
+        return 0;
+    pci_del_capability(dev, PCI_CAP_ID_MSIX, MSIX_CAP_LENGTH);
+    dev->msix_cap = 0;
+    msix_free_irq_entries(dev);
+    dev->msix_entries_nr = 0;
+    cpu_unregister_io_memory(dev->msix_mmio_index);
+    qemu_free(dev->msix_table_page);
+    dev->msix_table_page = NULL;
+    qemu_free(dev->msix_entry_used);
+    dev->msix_entry_used = NULL;
+    dev->cap_present &= ~QEMU_PCI_CAP_MSIX;
+    return 0;
+}
+
+void msix_save(PCIDevice *dev, QEMUFile *f)
+{
+    unsigned nentries = (pci_get_word(dev->config + PCI_MSIX_FLAGS) &
+                         PCI_MSIX_FLAGS_QSIZE) + 1;
+    qemu_put_buffer(f, dev->msix_table_page, nentries * MSIX_ENTRY_SIZE);
+    qemu_put_buffer(f, dev->msix_table_page + MSIX_PAGE_PENDING,
+                    (nentries + 7) / 8);
+}
+
+/* Should be called after restoring the config space. */
+void msix_load(PCIDevice *dev, QEMUFile *f)
+{
+    unsigned n = dev->msix_entries_nr;
+
+    if (!dev->cap_present & QEMU_PCI_CAP_MSIX)
+        return;
+
+    qemu_get_buffer(f, dev->msix_table_page, n * MSIX_ENTRY_SIZE);
+    qemu_get_buffer(f, dev->msix_table_page + MSIX_PAGE_PENDING, (n + 7) / 8);
+}
+
+/* Does device support MSI-X? */
+int msix_present(PCIDevice *dev)
+{
+    return dev->cap_present & QEMU_PCI_CAP_MSIX;
+}
+
+/* Is MSI-X enabled? */
+int msix_enabled(PCIDevice *dev)
+{
+    return (dev->cap_present & QEMU_PCI_CAP_MSIX) &&
+        (dev->config[dev->msix_cap + MSIX_ENABLE_OFFSET] &
+         MSIX_ENABLE_MASK);
+}
+
+/* Size of bar where MSI-X table resides, or 0 if MSI-X not supported. */
+uint32_t msix_bar_size(PCIDevice *dev)
+{
+    return (dev->cap_present & QEMU_PCI_CAP_MSIX) ?
+        dev->msix_bar_size : 0;
+}
+
+/* Send an MSI-X message */
+void msix_notify(PCIDevice *dev, unsigned vector)
+{
+    uint8_t *table_entry = dev->msix_table_page + vector * MSIX_ENTRY_SIZE;
+    uint64_t address;
+    uint32_t data;
+
+    if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])
+        return;
+    if (msix_is_masked(dev, vector)) {
+        msix_set_pending(dev, vector);
+        return;
+    }
+
+    address = pci_get_long(table_entry + MSIX_MSG_UPPER_ADDR);
+    address = (address << 32) | pci_get_long(table_entry + MSIX_MSG_ADDR);
+    data = pci_get_long(table_entry + MSIX_MSG_DATA);
+    stl_phys(address, data);
+}
+
+void msix_reset(PCIDevice *dev)
+{
+    if (!(dev->cap_present & QEMU_PCI_CAP_MSIX))
+        return;
+    msix_free_irq_entries(dev);
+    dev->config[dev->msix_cap + MSIX_ENABLE_OFFSET] &= MSIX_ENABLE_MASK;
+    memset(dev->msix_table_page, 0, MSIX_PAGE_SIZE);
+}
+
+/* PCI spec suggests that devices make it possible for software to configure
+ * less vectors than supported by the device, but does not specify a standard
+ * mechanism for devices to do so.
+ *
+ * We support this by asking devices to declare vectors software is going to
+ * actually use, and checking this on the notification path. Devices that
+ * don't want to follow the spec suggestion can declare all vectors as used. */
+
+/* Mark vector as used. */
+int msix_vector_use(PCIDevice *dev, unsigned vector)
+{
+    if (vector >= dev->msix_entries_nr)
+        return -EINVAL;
+    dev->msix_entry_used[vector]++;
+    return 0;
+}
+
+/* Mark vector as unused. */
+void msix_vector_unuse(PCIDevice *dev, unsigned vector)
+{
+    if (vector < dev->msix_entries_nr && dev->msix_entry_used[vector])
+        --dev->msix_entry_used[vector];
+}
diff --git a/hw/msix.h b/hw/msix.h
new file mode 100644
index 0000000000..3427778dc1
--- /dev/null
+++ b/hw/msix.h
@@ -0,0 +1,34 @@
+#ifndef QEMU_MSIX_H
+#define QEMU_MSIX_H
+
+#include "qemu-common.h"
+
+int msix_init(PCIDevice *pdev, unsigned short nentries,
+              unsigned bar_nr, unsigned bar_size);
+
+void msix_write_config(PCIDevice *pci_dev, uint32_t address,
+                       uint32_t val, int len);
+
+void msix_mmio_map(PCIDevice *pci_dev, int region_num,
+                   uint32_t addr, uint32_t size, int type);
+
+int msix_uninit(PCIDevice *d);
+
+void msix_save(PCIDevice *dev, QEMUFile *f);
+void msix_load(PCIDevice *dev, QEMUFile *f);
+
+int msix_enabled(PCIDevice *dev);
+int msix_present(PCIDevice *dev);
+
+uint32_t msix_bar_size(PCIDevice *dev);
+
+int msix_vector_use(PCIDevice *dev, unsigned vector);
+void msix_vector_unuse(PCIDevice *dev, unsigned vector);
+
+void msix_notify(PCIDevice *dev, unsigned vector);
+
+void msix_reset(PCIDevice *dev);
+
+extern int msix_supported;
+
+#endif
diff --git a/hw/pci.h b/hw/pci.h
index 8b5edef003..87b5a3cf24 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -155,6 +155,11 @@ typedef struct PCIIORegion {
 /* Size of the standard PCI config space */
 #define PCI_CONFIG_SPACE_SIZE 0x100
 
+/* Bits in cap_present field. */
+enum {
+    QEMU_PCI_CAP_MSIX = 0x1,
+};
+
 struct PCIDevice {
     DeviceState qdev;
     /* PCI config space */
@@ -186,6 +191,24 @@ struct PCIDevice {
 
     /* Current IRQ levels.  Used internally by the generic PCI code.  */
     int irq_state[4];
+
+    /* Capability bits */
+    uint32_t cap_present;
+
+    /* Offset of MSI-X capability in config space */
+    uint8_t msix_cap;
+
+    /* MSI-X entries */
+    int msix_entries_nr;
+
+    /* Space to store MSIX table */
+    uint8_t *msix_table_page;
+    /* MMIO index used to map MSIX table and pending bit entries. */
+    int msix_mmio_index;
+    /* Reference-count for entries actually in use by driver. */
+    unsigned *msix_entry_used;
+    /* Region including the MSI-X table */
+    uint32_t msix_bar_size;
 };
 
 PCIDevice *pci_register_device(PCIBus *bus, const char *name,