From: Steve Sistare <steven.sistare@oracle.com>
Date: Tue, 10 Jun 2025 15:39:18 +0000 (-0700)
Subject: vfio/container: discard old DMA vaddr
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1faadd96306b428f2e8e35f71761c333a6777f55;p=thirdparty%2Fqemu.git

vfio/container: discard old DMA vaddr

In the container pre_save handler, discard the virtual addresses in DMA
mappings with VFIO_DMA_UNMAP_FLAG_VADDR, because guest RAM will be
remapped at a different VA after in new QEMU.  DMA to already-mapped
pages continues.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/1749569991-25171-6-git-send-email-steven.sistare@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---

diff --git a/hw/vfio/cpr-legacy.c b/hw/vfio/cpr-legacy.c
index ac4a9ab315..ef106d0ea8 100644
--- a/hw/vfio/cpr-legacy.c
+++ b/hw/vfio/cpr-legacy.c
@@ -15,6 +15,22 @@
 #include "migration/vmstate.h"
 #include "qapi/error.h"
 
+static bool vfio_dma_unmap_vaddr_all(VFIOContainer *container, Error **errp)
+{
+    struct vfio_iommu_type1_dma_unmap unmap = {
+        .argsz = sizeof(unmap),
+        .flags = VFIO_DMA_UNMAP_FLAG_VADDR | VFIO_DMA_UNMAP_FLAG_ALL,
+        .iova = 0,
+        .size = 0,
+    };
+    if (ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, &unmap)) {
+        error_setg_errno(errp, errno, "vfio_dma_unmap_vaddr_all");
+        return false;
+    }
+    return true;
+}
+
+
 static bool vfio_cpr_supported(VFIOContainer *container, Error **errp)
 {
     if (!ioctl(container->fd, VFIO_CHECK_EXTENSION, VFIO_UPDATE_VADDR)) {
@@ -30,10 +46,23 @@ static bool vfio_cpr_supported(VFIOContainer *container, Error **errp)
     }
 }
 
+static int vfio_container_pre_save(void *opaque)
+{
+    VFIOContainer *container = opaque;
+    Error *local_err = NULL;
+
+    if (!vfio_dma_unmap_vaddr_all(container, &local_err)) {
+        error_report_err(local_err);
+        return -1;
+    }
+    return 0;
+}
+
 static const VMStateDescription vfio_container_vmstate = {
     .name = "vfio-container",
     .version_id = 0,
     .minimum_version_id = 0,
+    .pre_save = vfio_container_pre_save,
     .needed = cpr_incoming_needed,
     .fields = (VMStateField[]) {
         VMSTATE_END_OF_LIST()