VFIO updates 2016-10-31

- Replace skip_dump with ram_device to denote device memory and mark
    as non-direct to avoid memcpy to MMIO - fixes RTL (Alex Williamson)
  - Skip zero-length sparse mmaps - avoids unnecessary warning
    (Alex Williamson)
  - Clear BARs on reset so guest doesn't assume programming on return
    from S3 (Ido Yariv)
  - Enable sub-page MMIO mmaps - performance improvement for devices
    with smaller BARs, iff both host and guest map them to full,
    aligned pages (Yongji Xie)
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Merge remote-tracking branch 'remotes/awilliam/tags/vfio-updates-20161031.0' into staging

VFIO updates 2016-10-31

 - Replace skip_dump with ram_device to denote device memory and mark
   as non-direct to avoid memcpy to MMIO - fixes RTL (Alex Williamson)
 - Skip zero-length sparse mmaps - avoids unnecessary warning
   (Alex Williamson)
 - Clear BARs on reset so guest doesn't assume programming on return
   from S3 (Ido Yariv)
 - Enable sub-page MMIO mmaps - performance improvement for devices
   with smaller BARs, iff both host and guest map them to full,
   aligned pages (Yongji Xie)

# gpg: Signature made Mon 31 Oct 2016 17:26:47 GMT
# gpg:                using RSA key 0x239B9B6E3BB08B22
# gpg: Good signature from "Alex Williamson <alex.williamson@redhat.com>"
# gpg:                 aka "Alex Williamson <alex@shazbot.org>"
# gpg:                 aka "Alex Williamson <alwillia@redhat.com>"
# gpg:                 aka "Alex Williamson <alex.l.williamson@gmail.com>"
# Primary key fingerprint: 42F6 C04E 540B D1A9 9E7B  8A90 239B 9B6E 3BB0 8B22

* remotes/awilliam/tags/vfio-updates-20161031.0:
  vfio: Add support for mmapping sub-page MMIO BARs
  vfio/pci: fix out-of-sync BAR information on reset
  vfio: Handle zero-length sparse mmap ranges
  memory: Don't use memcpy for ram_device regions
  memory: Replace skip_dump flag with "ram_device"

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/vfio/common.c

@@ -610,16 +610,16 @@ vfio_get_region_info_cap(struct vfio_region_info *info, uint16_t id)
     return NULL;
 }
 
-static void vfio_setup_region_sparse_mmaps(VFIORegion *region,
-                                           struct vfio_region_info *info)
+static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
+                                          struct vfio_region_info *info)
 {
     struct vfio_info_cap_header *hdr;
     struct vfio_region_info_cap_sparse_mmap *sparse;
-    int i;
+    int i, j;
 
     hdr = vfio_get_region_info_cap(info, VFIO_REGION_INFO_CAP_SPARSE_MMAP);
     if (!hdr) {
-        return;
+        return -ENODEV;
     }
 
     sparse = container_of(hdr, struct vfio_region_info_cap_sparse_mmap, header);
@@ -627,16 +627,24 @@ static void vfio_setup_region_sparse_mmaps(VFIORegion *region,
     trace_vfio_region_sparse_mmap_header(region->vbasedev->name,
                                          region->nr, sparse->nr_areas);
 
-    region->nr_mmaps = sparse->nr_areas;
-    region->mmaps = g_new0(VFIOMmap, region->nr_mmaps);
+    region->mmaps = g_new0(VFIOMmap, sparse->nr_areas);
 
-    for (i = 0; i < region->nr_mmaps; i++) {
-        region->mmaps[i].offset = sparse->areas[i].offset;
-        region->mmaps[i].size = sparse->areas[i].size;
-        trace_vfio_region_sparse_mmap_entry(i, region->mmaps[i].offset,
-                                            region->mmaps[i].offset +
-                                            region->mmaps[i].size);
+    for (i = 0, j = 0; i < sparse->nr_areas; i++) {
+        trace_vfio_region_sparse_mmap_entry(i, sparse->areas[i].offset,
+                                            sparse->areas[i].offset +
+                                            sparse->areas[i].size);
+
+        if (sparse->areas[i].size) {
+            region->mmaps[j].offset = sparse->areas[i].offset;
+            region->mmaps[j].size = sparse->areas[i].size;
+            j++;
+        }
     }
+
+    region->nr_mmaps = j;
+    region->mmaps = g_realloc(region->mmaps, j * sizeof(VFIOMmap));
+
+    return 0;
 }
 
 int vfio_region_setup(Object *obj, VFIODevice *vbasedev, VFIORegion *region,
@@ -662,12 +670,11 @@ int vfio_region_setup(Object *obj, VFIODevice *vbasedev, VFIORegion *region,
                               region, name, region->size);
 
         if (!vbasedev->no_mmap &&
-            region->flags & VFIO_REGION_INFO_FLAG_MMAP &&
-            !(region->size & ~qemu_real_host_page_mask)) {
+            region->flags & VFIO_REGION_INFO_FLAG_MMAP) {
 
-            vfio_setup_region_sparse_mmaps(region, info);
+            ret = vfio_setup_region_sparse_mmaps(region, info);
 
-            if (!region->nr_mmaps) {
+            if (ret) {
                 region->nr_mmaps = 1;
                 region->mmaps = g_new0(VFIOMmap, region->nr_mmaps);
                 region->mmaps[0].offset = 0;
@@ -724,12 +731,11 @@ int vfio_region_mmap(VFIORegion *region)
 
         name = g_strdup_printf("%s mmaps[%d]",
                                memory_region_name(region->mem), i);
-        memory_region_init_ram_ptr(&region->mmaps[i].mem,
-                                   memory_region_owner(region->mem),
-                                   name, region->mmaps[i].size,
-                                   region->mmaps[i].mmap);
+        memory_region_init_ram_device_ptr(&region->mmaps[i].mem,
+                                          memory_region_owner(region->mem),
+                                          name, region->mmaps[i].size,
+                                          region->mmaps[i].mmap);
         g_free(name);
-        memory_region_set_skip_dump(&region->mmaps[i].mem);
         memory_region_add_subregion(region->mem, region->mmaps[i].offset,
                                     &region->mmaps[i].mem);
 

hw/vfio/pci.c

@@ -1070,6 +1070,55 @@ static const MemoryRegionOps vfio_vga_ops = {
     .endianness = DEVICE_LITTLE_ENDIAN,
 };
 
+/*
+ * Expand memory region of sub-page(size < PAGE_SIZE) MMIO BAR to page
+ * size if the BAR is in an exclusive page in host so that we could map
+ * this BAR to guest. But this sub-page BAR may not occupy an exclusive
+ * page in guest. So we should set the priority of the expanded memory
+ * region to zero in case of overlap with BARs which share the same page
+ * with the sub-page BAR in guest. Besides, we should also recover the
+ * size of this sub-page BAR when its base address is changed in guest
+ * and not page aligned any more.
+ */
+static void vfio_sub_page_bar_update_mapping(PCIDevice *pdev, int bar)
+{
+    VFIOPCIDevice *vdev = DO_UPCAST(VFIOPCIDevice, pdev, pdev);
+    VFIORegion *region = &vdev->bars[bar].region;
+    MemoryRegion *mmap_mr, *mr;
+    PCIIORegion *r;
+    pcibus_t bar_addr;
+    uint64_t size = region->size;
+
+    /* Make sure that the whole region is allowed to be mmapped */
+    if (region->nr_mmaps != 1 || !region->mmaps[0].mmap ||
+        region->mmaps[0].size != region->size) {
+        return;
+    }
+
+    r = &pdev->io_regions[bar];
+    bar_addr = r->addr;
+    mr = region->mem;
+    mmap_mr = &region->mmaps[0].mem;
+
+    /* If BAR is mapped and page aligned, update to fill PAGE_SIZE */
+    if (bar_addr != PCI_BAR_UNMAPPED &&
+        !(bar_addr & ~qemu_real_host_page_mask)) {
+        size = qemu_real_host_page_size;
+    }
+
+    memory_region_transaction_begin();
+
+    memory_region_set_size(mr, size);
+    memory_region_set_size(mmap_mr, size);
+    if (size != region->size && memory_region_is_mapped(mr)) {
+        memory_region_del_subregion(r->address_space, mr);
+        memory_region_add_subregion_overlap(r->address_space,
+                                            bar_addr, mr, 0);
+    }
+
+    memory_region_transaction_commit();
+}
+
 /*
  * PCI config space
  */
@@ -1153,6 +1202,24 @@ void vfio_pci_write_config(PCIDevice *pdev,
         } else if (was_enabled && !is_enabled) {
             vfio_msix_disable(vdev);
         }
+    } else if (ranges_overlap(addr, len, PCI_BASE_ADDRESS_0, 24) ||
+        range_covers_byte(addr, len, PCI_COMMAND)) {
+        pcibus_t old_addr[PCI_NUM_REGIONS - 1];
+        int bar;
+
+        for (bar = 0; bar < PCI_ROM_SLOT; bar++) {
+            old_addr[bar] = pdev->io_regions[bar].addr;
+        }
+
+        pci_default_write_config(pdev, addr, val, len);
+
+        for (bar = 0; bar < PCI_ROM_SLOT; bar++) {
+            if (old_addr[bar] != pdev->io_regions[bar].addr &&
+                pdev->io_regions[bar].size > 0 &&
+                pdev->io_regions[bar].size < qemu_real_host_page_size) {
+                vfio_sub_page_bar_update_mapping(pdev, bar);
+            }
+        }
     } else {
         /* Write everything to QEMU to keep emulated bits correct */
         pci_default_write_config(pdev, addr, val, len);
@@ -1922,11 +1989,23 @@ static void vfio_pci_pre_reset(VFIOPCIDevice *vdev)
 static void vfio_pci_post_reset(VFIOPCIDevice *vdev)
 {
     Error *err = NULL;
+    int nr;
 
     vfio_intx_enable(vdev, &err);
     if (err) {
         error_reportf_err(err, ERR_PREFIX, vdev->vbasedev.name);
     }
+
+    for (nr = 0; nr < PCI_NUM_REGIONS - 1; ++nr) {
+        off_t addr = vdev->config_offset + PCI_BASE_ADDRESS_0 + (4 * nr);
+        uint32_t val = 0;
+        uint32_t len = sizeof(val);
+
+        if (pwrite(vdev->vbasedev.fd, &val, len, addr) != len) {
+            error_report("%s(%s) reset bar %d failed: %m", __func__,
+                         vdev->vbasedev.name, nr);
+        }
+    }
 }
 
 static bool vfio_pci_host_match(PCIHostDeviceAddress *addr, const char *name)

hw/vfio/spapr.c

@@ -25,7 +25,7 @@ static bool vfio_prereg_listener_skipped_section(MemoryRegionSection *section)
     }
 
     return !memory_region_is_ram(section->mr) ||
-            memory_region_is_skip_dump(section->mr);
+            memory_region_is_ram_device(section->mr);
 }
 
 static void *vfio_prereg_gpa_to_vaddr(MemoryRegionSection *section, hwaddr gpa)