vfio-user: handle DMA mappings

Define and register callbacks to manage the RAM regions used for
device DMA

Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: faacbcd45c4d02c591f0dbfdc19041fbb3eae7eb.1655151679.git.jag.raman@oracle.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

3 files changed, 62 insertions, 0 deletions

diff --git a/hw/remote/machine.c b/hw/remote/machine.c
index cbb2add291..645b54343d 100644
--- a/hw/remote/machine.c
+++ b/hw/remote/machine.c
@@ -22,6 +22,7 @@
 #include "hw/remote/iohub.h"
 #include "hw/remote/iommu.h"
 #include "hw/qdev-core.h"
+#include "hw/remote/iommu.h"
 
 static void remote_machine_init(MachineState *machine)
 {
@@ -51,6 +52,10 @@ static void remote_machine_init(MachineState *machine)
 
     pci_host = PCI_HOST_BRIDGE(rem_host);
 
+    if (s->vfio_user) {
+        remote_iommu_setup(pci_host->bus);
+    }
+
     remote_iohub_init(&s->iohub);
 
     pci_bus_irqs(pci_host->bus, remote_iohub_set_irq, remote_iohub_map_irq,
diff --git a/hw/remote/trace-events b/hw/remote/trace-events
index 2ef7884346..f945c7e33b 100644
--- a/hw/remote/trace-events
+++ b/hw/remote/trace-events
@@ -7,3 +7,5 @@ mpqemu_recv_io_error(int cmd, int size, int nfds) "failed to receive %d size %d,
 vfu_prop(const char *prop, const char *val) "vfu: setting %s as %s"
 vfu_cfg_read(uint32_t offset, uint32_t val) "vfu: cfg: 0x%u -> 0x%x"
 vfu_cfg_write(uint32_t offset, uint32_t val) "vfu: cfg: 0x%u <- 0x%x"
+vfu_dma_register(uint64_t gpa, size_t len) "vfu: registering GPA 0x%"PRIx64", %zu bytes"
+vfu_dma_unregister(uint64_t gpa) "vfu: unregistering GPA 0x%"PRIx64""
diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c
index cef473cb98..7b21f77052 100644
--- a/hw/remote/vfio-user-obj.c
+++ b/hw/remote/vfio-user-obj.c
@@ -284,6 +284,54 @@ static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf,
     return count;
 }
 
+static void dma_register(vfu_ctx_t *vfu_ctx, vfu_dma_info_t *info)
+{
+    VfuObject *o = vfu_get_private(vfu_ctx);
+    AddressSpace *dma_as = NULL;
+    MemoryRegion *subregion = NULL;
+    g_autofree char *name = NULL;
+    struct iovec *iov = &info->iova;
+
+    if (!info->vaddr) {
+        return;
+    }
+
+    name = g_strdup_printf("mem-%s-%"PRIx64"", o->device,
+                           (uint64_t)info->vaddr);
+
+    subregion = g_new0(MemoryRegion, 1);
+
+    memory_region_init_ram_ptr(subregion, NULL, name,
+                               iov->iov_len, info->vaddr);
+
+    dma_as = pci_device_iommu_address_space(o->pci_dev);
+
+    memory_region_add_subregion(dma_as->root, (hwaddr)iov->iov_base, subregion);
+
+    trace_vfu_dma_register((uint64_t)iov->iov_base, iov->iov_len);
+}
+
+static void dma_unregister(vfu_ctx_t *vfu_ctx, vfu_dma_info_t *info)
+{
+    VfuObject *o = vfu_get_private(vfu_ctx);
+    AddressSpace *dma_as = NULL;
+    MemoryRegion *mr = NULL;
+    ram_addr_t offset;
+
+    mr = memory_region_from_host(info->vaddr, &offset);
+    if (!mr) {
+        return;
+    }
+
+    dma_as = pci_device_iommu_address_space(o->pci_dev);
+
+    memory_region_del_subregion(dma_as->root, mr);
+
+    object_unparent((OBJECT(mr)));
+
+    trace_vfu_dma_unregister((uint64_t)info->iova.iov_base);
+}
+
 /*
  * TYPE_VFU_OBJECT depends on the availability of the 'socket' and 'device'
  * properties. It also depends on devices instantiated in QEMU. These
@@ -387,6 +435,13 @@ static void vfu_object_init_ctx(VfuObject *o, Error **errp)
         goto fail;
     }
 
+    ret = vfu_setup_device_dma(o->vfu_ctx, &dma_register, &dma_unregister);
+    if (ret < 0) {
+        error_setg(errp, "vfu: Failed to setup DMA handlers for %s",
+                   o->device);
+        goto fail;
+    }
+
     ret = vfu_realize_ctx(o->vfu_ctx);
     if (ret < 0) {
         error_setg(errp, "vfu: Failed to realize device %s- %s",