vfio: Generalize region support

Both platform and PCI vfio drivers create a "slow", I/O memory region
with one or more mmap memory regions overlayed when supported by the
device. Generalize this to a set of common helpers in the core that
pulls the region info from vfio, fills the region data, configures
slow mapping, and adds helpers for comleting the mmap, enable/disable,
and teardown.  This can be immediately used by the PCI MSI-X code,
which needs to mmap around the MSI-X vector table.

This also changes VFIORegion.mem to be dynamically allocated because
otherwise we don't know how the caller has allocated VFIORegion and
therefore don't know whether to unreference it to destroy the
MemoryRegion or not.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 89 insertions, 79 deletions

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index db7a95026a..f18a678cf9 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -1166,6 +1166,74 @@ static int vfio_msi_setup(VFIOPCIDevice *vdev, int pos)
     return 0;
 }
 
+static void vfio_pci_fixup_msix_region(VFIOPCIDevice *vdev)
+{
+    off_t start, end;
+    VFIORegion *region = &vdev->bars[vdev->msix->table_bar].region;
+
+    /*
+     * We expect to find a single mmap covering the whole BAR, anything else
+     * means it's either unsupported or already setup.
+     */
+    if (region->nr_mmaps != 1 || region->mmaps[0].offset ||
+        region->size != region->mmaps[0].size) {
+        return;
+    }
+
+    /* MSI-X table start and end aligned to host page size */
+    start = vdev->msix->table_offset & qemu_real_host_page_mask;
+    end = REAL_HOST_PAGE_ALIGN((uint64_t)vdev->msix->table_offset +
+                               (vdev->msix->entries * PCI_MSIX_ENTRY_SIZE));
+
+    /*
+     * Does the MSI-X table cover the beginning of the BAR?  The whole BAR?
+     * NB - Host page size is necessarily a power of two and so is the PCI
+     * BAR (not counting EA yet), therefore if we have host page aligned
+     * @start and @end, then any remainder of the BAR before or after those
+     * must be at least host page sized and therefore mmap'able.
+     */
+    if (!start) {
+        if (end >= region->size) {
+            region->nr_mmaps = 0;
+            g_free(region->mmaps);
+            region->mmaps = NULL;
+            trace_vfio_msix_fixup(vdev->vbasedev.name,
+                                  vdev->msix->table_bar, 0, 0);
+        } else {
+            region->mmaps[0].offset = end;
+            region->mmaps[0].size = region->size - end;
+            trace_vfio_msix_fixup(vdev->vbasedev.name,
+                              vdev->msix->table_bar, region->mmaps[0].offset,
+                              region->mmaps[0].offset + region->mmaps[0].size);
+        }
+
+    /* Maybe it's aligned at the end of the BAR */
+    } else if (end >= region->size) {
+        region->mmaps[0].size = start;
+        trace_vfio_msix_fixup(vdev->vbasedev.name,
+                              vdev->msix->table_bar, region->mmaps[0].offset,
+                              region->mmaps[0].offset + region->mmaps[0].size);
+
+    /* Otherwise it must split the BAR */
+    } else {
+        region->nr_mmaps = 2;
+        region->mmaps = g_renew(VFIOMmap, region->mmaps, 2);
+
+        memcpy(&region->mmaps[1], &region->mmaps[0], sizeof(VFIOMmap));
+
+        region->mmaps[0].size = start;
+        trace_vfio_msix_fixup(vdev->vbasedev.name,
+                              vdev->msix->table_bar, region->mmaps[0].offset,
+                              region->mmaps[0].offset + region->mmaps[0].size);
+
+        region->mmaps[1].offset = end;
+        region->mmaps[1].size = region->size - end;
+        trace_vfio_msix_fixup(vdev->vbasedev.name,
+                              vdev->msix->table_bar, region->mmaps[1].offset,
+                              region->mmaps[1].offset + region->mmaps[1].size);
+    }
+}
+
 /*
  * We don't have any control over how pci_add_capability() inserts
  * capabilities into the chain.  In order to setup MSI-X we need a
@@ -1240,6 +1308,8 @@ static int vfio_msix_early_setup(VFIOPCIDevice *vdev)
                                 msix->table_offset, msix->entries);
     vdev->msix = msix;
 
+    vfio_pci_fixup_msix_region(vdev);
+
     return 0;
 }
 
@@ -1250,9 +1320,9 @@ static int vfio_msix_setup(VFIOPCIDevice *vdev, int pos)
     vdev->msix->pending = g_malloc0(BITS_TO_LONGS(vdev->msix->entries) *
                                     sizeof(unsigned long));
     ret = msix_init(&vdev->pdev, vdev->msix->entries,
-                    &vdev->bars[vdev->msix->table_bar].region.mem,
+                    vdev->bars[vdev->msix->table_bar].region.mem,
                     vdev->msix->table_bar, vdev->msix->table_offset,
-                    &vdev->bars[vdev->msix->pba_bar].region.mem,
+                    vdev->bars[vdev->msix->pba_bar].region.mem,
                     vdev->msix->pba_bar, vdev->msix->pba_offset, pos);
     if (ret < 0) {
         if (ret == -ENOTSUP) {
@@ -1289,8 +1359,8 @@ static void vfio_teardown_msi(VFIOPCIDevice *vdev)
 
     if (vdev->msix) {
         msix_uninit(&vdev->pdev,
-                    &vdev->bars[vdev->msix->table_bar].region.mem,
-                    &vdev->bars[vdev->msix->pba_bar].region.mem);
+                    vdev->bars[vdev->msix->table_bar].region.mem,
+                    vdev->bars[vdev->msix->pba_bar].region.mem);
         g_free(vdev->msix->pending);
     }
 }
@@ -1303,16 +1373,7 @@ static void vfio_mmap_set_enabled(VFIOPCIDevice *vdev, bool enabled)
     int i;
 
     for (i = 0; i < PCI_ROM_SLOT; i++) {
-        VFIOBAR *bar = &vdev->bars[i];
-
-        if (!bar->region.size) {
-            continue;
-        }
-
-        memory_region_set_enabled(&bar->region.mmap_mem, enabled);
-        if (vdev->msix && vdev->msix->table_bar == i) {
-            memory_region_set_enabled(&vdev->msix->mmap_mem, enabled);
-        }
+        vfio_region_mmaps_set_enabled(&vdev->bars[i].region, enabled);
     }
 }
 
@@ -1326,11 +1387,7 @@ static void vfio_unregister_bar(VFIOPCIDevice *vdev, int nr)
 
     vfio_bar_quirk_teardown(vdev, nr);
 
-    memory_region_del_subregion(&bar->region.mem, &bar->region.mmap_mem);
-
-    if (vdev->msix && vdev->msix->table_bar == nr) {
-        memory_region_del_subregion(&bar->region.mem, &vdev->msix->mmap_mem);
-    }
+    vfio_region_exit(&bar->region);
 }
 
 static void vfio_unmap_bar(VFIOPCIDevice *vdev, int nr)
@@ -1343,18 +1400,13 @@ static void vfio_unmap_bar(VFIOPCIDevice *vdev, int nr)
 
     vfio_bar_quirk_free(vdev, nr);
 
-    munmap(bar->region.mmap, memory_region_size(&bar->region.mmap_mem));
-
-    if (vdev->msix && vdev->msix->table_bar == nr) {
-        munmap(vdev->msix->mmap, memory_region_size(&vdev->msix->mmap_mem));
-    }
+    vfio_region_finalize(&bar->region);
 }
 
 static void vfio_map_bar(VFIOPCIDevice *vdev, int nr)
 {
     VFIOBAR *bar = &vdev->bars[nr];
     uint64_t size = bar->region.size;
-    char name[64];
     uint32_t pci_bar;
     uint8_t type;
     int ret;
@@ -1364,8 +1416,6 @@ static void vfio_map_bar(VFIOPCIDevice *vdev, int nr)
         return;
     }
 
-    snprintf(name, sizeof(name), "VFIO %s BAR %d", vdev->vbasedev.name, nr);
-
     /* Determine what type of BAR this is for registration */
     ret = pread(vdev->vbasedev.fd, &pci_bar, sizeof(pci_bar),
                 vdev->config_offset + PCI_BASE_ADDRESS_0 + (4 * nr));
@@ -1380,41 +1430,11 @@ static void vfio_map_bar(VFIOPCIDevice *vdev, int nr)
     type = pci_bar & (bar->ioport ? ~PCI_BASE_ADDRESS_IO_MASK :
                                     ~PCI_BASE_ADDRESS_MEM_MASK);
 
-    /* A "slow" read/write mapping underlies all BARs */
-    memory_region_init_io(&bar->region.mem, OBJECT(vdev), &vfio_region_ops,
-                          bar, name, size);
-    pci_register_bar(&vdev->pdev, nr, type, &bar->region.mem);
-
-    /*
-     * We can't mmap areas overlapping the MSIX vector table, so we
-     * potentially insert a direct-mapped subregion before and after it.
-     */
-    if (vdev->msix && vdev->msix->table_bar == nr) {
-        size = vdev->msix->table_offset & qemu_real_host_page_mask;
-    }
-
-    strncat(name, " mmap", sizeof(name) - strlen(name) - 1);
-    if (vfio_mmap_region(OBJECT(vdev), &bar->region, &bar->region.mem,
-                      &bar->region.mmap_mem, &bar->region.mmap,
-                      size, 0, name)) {
-        error_report("%s unsupported. Performance may be slow", name);
-    }
-
-    if (vdev->msix && vdev->msix->table_bar == nr) {
-        uint64_t start;
-
-        start = REAL_HOST_PAGE_ALIGN((uint64_t)vdev->msix->table_offset +
-                                     (vdev->msix->entries *
-                                      PCI_MSIX_ENTRY_SIZE));
+    pci_register_bar(&vdev->pdev, nr, type, bar->region.mem);
 
-        size = start < bar->region.size ? bar->region.size - start : 0;
-        strncat(name, " msix-hi", sizeof(name) - strlen(name) - 1);
-        /* VFIOMSIXInfo contains another MemoryRegion for this mapping */
-        if (vfio_mmap_region(OBJECT(vdev), &bar->region, &bar->region.mem,
-                          &vdev->msix->mmap_mem,
-                          &vdev->msix->mmap, size, start, name)) {
-            error_report("%s unsupported. Performance may be slow", name);
-        }
+    if (vfio_region_mmap(&bar->region)) {
+        error_report("Failed to mmap %s BAR %d. Performance may be slow",
+                     vdev->vbasedev.name, nr);
     }
 
     vfio_bar_quirk_setup(vdev, nr);
@@ -2049,25 +2069,18 @@ static int vfio_populate_device(VFIOPCIDevice *vdev)
     }
 
     for (i = VFIO_PCI_BAR0_REGION_INDEX; i < VFIO_PCI_ROM_REGION_INDEX; i++) {
-        ret = vfio_get_region_info(vbasedev, i, &reg_info);
+        char *name = g_strdup_printf("%s BAR %d", vbasedev->name, i);
+
+        ret = vfio_region_setup(OBJECT(vdev), vbasedev,
+                                &vdev->bars[i].region, i, name);
+        g_free(name);
+
         if (ret) {
             error_report("vfio: Error getting region %d info: %m", i);
             goto error;
         }
 
-        trace_vfio_populate_device_region(vbasedev->name, i,
-                                          (unsigned long)reg_info->size,
-                                          (unsigned long)reg_info->offset,
-                                          (unsigned long)reg_info->flags);
-
-        vdev->bars[i].region.vbasedev = vbasedev;
-        vdev->bars[i].region.flags = reg_info->flags;
-        vdev->bars[i].region.size = reg_info->size;
-        vdev->bars[i].region.fd_offset = reg_info->offset;
-        vdev->bars[i].region.nr = i;
         QLIST_INIT(&vdev->bars[i].quirks);
-
-        g_free(reg_info);
     }
 
     ret = vfio_get_region_info(vbasedev,
@@ -2153,11 +2166,8 @@ error:
 static void vfio_put_device(VFIOPCIDevice *vdev)
 {
     g_free(vdev->vbasedev.name);
-    if (vdev->msix) {
-        object_unparent(OBJECT(&vdev->msix->mmap_mem));
-        g_free(vdev->msix);
-        vdev->msix = NULL;
-    }
+    g_free(vdev->msix);
+
     vfio_put_base_device(&vdev->vbasedev);
 }