Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 255 insertions, 0 deletions

diff --git a/hw/vfio/spapr.c b/hw/vfio/spapr.c
new file mode 100644
index 000000000..04c6e67f8
--- /dev/null
+++ b/hw/vfio/spapr.c
@@ -0,0 +1,255 @@
+/*
+ * DMA memory preregistration
+ *
+ * Authors:
+ *  Alexey Kardashevskiy <aik@ozlabs.ru>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include <sys/ioctl.h>
+#include <linux/vfio.h>
+
+#include "hw/vfio/vfio-common.h"
+#include "hw/hw.h"
+#include "exec/ram_addr.h"
+#include "qemu/error-report.h"
+#include "qapi/error.h"
+#include "trace.h"
+
+static bool vfio_prereg_listener_skipped_section(MemoryRegionSection *section)
+{
+    if (memory_region_is_iommu(section->mr)) {
+        hw_error("Cannot possibly preregister IOMMU memory");
+    }
+
+    return !memory_region_is_ram(section->mr) ||
+            memory_region_is_ram_device(section->mr);
+}
+
+static void *vfio_prereg_gpa_to_vaddr(MemoryRegionSection *section, hwaddr gpa)
+{
+    return memory_region_get_ram_ptr(section->mr) +
+        section->offset_within_region +
+        (gpa - section->offset_within_address_space);
+}
+
+static void vfio_prereg_listener_region_add(MemoryListener *listener,
+                                            MemoryRegionSection *section)
+{
+    VFIOContainer *container = container_of(listener, VFIOContainer,
+                                            prereg_listener);
+    const hwaddr gpa = section->offset_within_address_space;
+    hwaddr end;
+    int ret;
+    hwaddr page_mask = qemu_real_host_page_mask;
+    struct vfio_iommu_spapr_register_memory reg = {
+        .argsz = sizeof(reg),
+        .flags = 0,
+    };
+
+    if (vfio_prereg_listener_skipped_section(section)) {
+        trace_vfio_prereg_listener_region_add_skip(
+                section->offset_within_address_space,
+                section->offset_within_address_space +
+                int128_get64(int128_sub(section->size, int128_one())));
+        return;
+    }
+
+    if (unlikely((section->offset_within_address_space & ~page_mask) ||
+                 (section->offset_within_region & ~page_mask) ||
+                 (int128_get64(section->size) & ~page_mask))) {
+        error_report("%s received unaligned region", __func__);
+        return;
+    }
+
+    end = section->offset_within_address_space + int128_get64(section->size);
+    if (gpa >= end) {
+        return;
+    }
+
+    memory_region_ref(section->mr);
+
+    reg.vaddr = (uintptr_t) vfio_prereg_gpa_to_vaddr(section, gpa);
+    reg.size = end - gpa;
+
+    ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_REGISTER_MEMORY, &reg);
+    trace_vfio_prereg_register(reg.vaddr, reg.size, ret ? -errno : 0);
+    if (ret) {
+        /*
+         * On the initfn path, store the first error in the container so we
+         * can gracefully fail.  Runtime, there's not much we can do other
+         * than throw a hardware error.
+         */
+        if (!container->initialized) {
+            if (!container->error) {
+                error_setg_errno(&container->error, -ret,
+                                 "Memory registering failed");
+            }
+        } else {
+            hw_error("vfio: Memory registering failed, unable to continue");
+        }
+    }
+}
+
+static void vfio_prereg_listener_region_del(MemoryListener *listener,
+                                            MemoryRegionSection *section)
+{
+    VFIOContainer *container = container_of(listener, VFIOContainer,
+                                            prereg_listener);
+    const hwaddr gpa = section->offset_within_address_space;
+    hwaddr end;
+    int ret;
+    hwaddr page_mask = qemu_real_host_page_mask;
+    struct vfio_iommu_spapr_register_memory reg = {
+        .argsz = sizeof(reg),
+        .flags = 0,
+    };
+
+    if (vfio_prereg_listener_skipped_section(section)) {
+        trace_vfio_prereg_listener_region_del_skip(
+                section->offset_within_address_space,
+                section->offset_within_address_space +
+                int128_get64(int128_sub(section->size, int128_one())));
+        return;
+    }
+
+    if (unlikely((section->offset_within_address_space & ~page_mask) ||
+                 (section->offset_within_region & ~page_mask) ||
+                 (int128_get64(section->size) & ~page_mask))) {
+        error_report("%s received unaligned region", __func__);
+        return;
+    }
+
+    end = section->offset_within_address_space + int128_get64(section->size);
+    if (gpa >= end) {
+        return;
+    }
+
+    reg.vaddr = (uintptr_t) vfio_prereg_gpa_to_vaddr(section, gpa);
+    reg.size = end - gpa;
+
+    ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY, &reg);
+    trace_vfio_prereg_unregister(reg.vaddr, reg.size, ret ? -errno : 0);
+}
+
+const MemoryListener vfio_prereg_listener = {
+    .name = "vfio-pre-reg",
+    .region_add = vfio_prereg_listener_region_add,
+    .region_del = vfio_prereg_listener_region_del,
+};
+
+int vfio_spapr_create_window(VFIOContainer *container,
+                             MemoryRegionSection *section,
+                             hwaddr *pgsize)
+{
+    int ret = 0;
+    IOMMUMemoryRegion *iommu_mr = IOMMU_MEMORY_REGION(section->mr);
+    uint64_t pagesize = memory_region_iommu_get_min_page_size(iommu_mr), pgmask;
+    unsigned entries, bits_total, bits_per_level, max_levels;
+    struct vfio_iommu_spapr_tce_create create = { .argsz = sizeof(create) };
+    long rampagesize = qemu_minrampagesize();
+
+    /*
+     * The host might not support the guest supported IOMMU page size,
+     * so we will use smaller physical IOMMU pages to back them.
+     */
+    if (pagesize > rampagesize) {
+        pagesize = rampagesize;
+    }
+    pgmask = container->pgsizes & (pagesize | (pagesize - 1));
+    pagesize = pgmask ? (1ULL << (63 - clz64(pgmask))) : 0;
+    if (!pagesize) {
+        error_report("Host doesn't support page size 0x%"PRIx64
+                     ", the supported mask is 0x%lx",
+                     memory_region_iommu_get_min_page_size(iommu_mr),
+                     container->pgsizes);
+        return -EINVAL;
+    }
+
+    /*
+     * FIXME: For VFIO iommu types which have KVM acceleration to
+     * avoid bouncing all map/unmaps through qemu this way, this
+     * would be the right place to wire that up (tell the KVM
+     * device emulation the VFIO iommu handles to use).
+     */
+    create.window_size = int128_get64(section->size);
+    create.page_shift = ctz64(pagesize);
+    /*
+     * SPAPR host supports multilevel TCE tables. We try to guess optimal
+     * levels number and if this fails (for example due to the host memory
+     * fragmentation), we increase levels. The DMA address structure is:
+     * rrrrrrrr rxxxxxxx xxxxxxxx xxxxxxxx  xxxxxxxx xxxxxxxx xxxxxxxx iiiiiiii
+     * where:
+     *   r = reserved (bits >= 55 are reserved in the existing hardware)
+     *   i = IOMMU page offset (64K in this example)
+     *   x = bits to index a TCE which can be split to equal chunks to index
+     *      within the level.
+     * The aim is to split "x" to smaller possible number of levels.
+     */
+    entries = create.window_size >> create.page_shift;
+    /* bits_total is number of "x" needed */
+    bits_total = ctz64(entries * sizeof(uint64_t));
+    /*
+     * bits_per_level is a safe guess of how much we can allocate per level:
+     * 8 is the current minimum for CONFIG_FORCE_MAX_ZONEORDER and MAX_ORDER
+     * is usually bigger than that.
+     * Below we look at qemu_real_host_page_size as TCEs are allocated from
+     * system pages.
+     */
+    bits_per_level = ctz64(qemu_real_host_page_size) + 8;
+    create.levels = bits_total / bits_per_level;
+    if (bits_total % bits_per_level) {
+        ++create.levels;
+    }
+    max_levels = (64 - create.page_shift) / ctz64(qemu_real_host_page_size);
+    for ( ; create.levels <= max_levels; ++create.levels) {
+        ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_CREATE, &create);
+        if (!ret) {
+            break;
+        }
+    }
+    if (ret) {
+        error_report("Failed to create a window, ret = %d (%m)", ret);
+        return -errno;
+    }
+
+    if (create.start_addr != section->offset_within_address_space) {
+        vfio_spapr_remove_window(container, create.start_addr);
+
+        error_report("Host doesn't support DMA window at %"HWADDR_PRIx", must be %"PRIx64,
+                     section->offset_within_address_space,
+                     (uint64_t)create.start_addr);
+        return -EINVAL;
+    }
+    trace_vfio_spapr_create_window(create.page_shift,
+                                   create.levels,
+                                   create.window_size,
+                                   create.start_addr);
+    *pgsize = pagesize;
+
+    return 0;
+}
+
+int vfio_spapr_remove_window(VFIOContainer *container,
+                             hwaddr offset_within_address_space)
+{
+    struct vfio_iommu_spapr_tce_remove remove = {
+        .argsz = sizeof(remove),
+        .start_addr = offset_within_address_space,
+    };
+    int ret;
+
+    ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_REMOVE, &remove);
+    if (ret) {
+        error_report("Failed to remove window at %"PRIx64,
+                     (uint64_t)remove.start_addr);
+        return -errno;
+    }
+
+    trace_vfio_spapr_remove_window(offset_within_address_space);
+
+    return 0;
+}