On 8/13/2025 11:24 PM, Zhenzhong Duan wrote:
If there are multiple containers and unmap-all fails for some container, we
need to remap vaddr for the other containers for which unmap-all succeeded.
When ram discard is enabled, we should only remap populated parts in a
section instead of the whole section.
Export vfio_ram_discard_notify_populate() and use it to do population.
Fixes: eba1f657cbb1 ("vfio/container: recover from unmap-all-vaddr failure")
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
btw: I didn't find easy to test this corner case, only code inspecting
Thanks Zhenzhong, this looks correct.
However, I never liked patch
eba1f657cbb1 ("vfio/container: recover from unmap-all-vaddr failure")
I think it adds too much complexity for a rare case. In fact, if we
examine all the possible error return codes, I believe they all would
be caused by other qemu application bugs, or kernel bugs:
vfio_dma_do_unmap()
returns -EBUSY if an mdev exists. qemu blocks live update blocker
when mdev is present. If this occurs, the blocker has a bug.
returns -EINVAL if the vaddr was already invalidated. qemu already
invalidated it, or never remapped the vaddr after a previous live
update. Both are qemu bugs.
iopt_unmap_all
iopt_unmap_iova_range
-EBUSY - qemu is concurrently performing other dma map or unmap
operations. a bug.
-EDEADLOCK - Something is not responding to unmap requests.
Therefore, I think we should just revert eba1f657cbb1, and assert that
the qemu vfio_dma_unmap_vaddr_all() call succeeds.
Thoughts?
- Steve
include/hw/vfio/vfio-container-base.h | 3 +++
include/hw/vfio/vfio-cpr.h | 2 +-
hw/vfio/cpr-legacy.c | 19 ++++++++++++++-----
hw/vfio/listener.c | 8 ++++----
4 files changed, 22 insertions(+), 10 deletions(-)
diff --git a/include/hw/vfio/vfio-container-base.h
b/include/hw/vfio/vfio-container-base.h
index bded6e993f..3f0c085143 100644
--- a/include/hw/vfio/vfio-container-base.h
+++ b/include/hw/vfio/vfio-container-base.h
@@ -269,6 +269,9 @@ struct VFIOIOMMUClass {
void (*release)(VFIOContainerBase *bcontainer);
};
+int vfio_ram_discard_notify_populate(RamDiscardListener *rdl,
+ MemoryRegionSection *section);
+
VFIORamDiscardListener *vfio_find_ram_discard_listener(
VFIOContainerBase *bcontainer, MemoryRegionSection *section);
diff --git a/include/hw/vfio/vfio-cpr.h b/include/hw/vfio/vfio-cpr.h
index d37daffbc5..fb32a5f873 100644
--- a/include/hw/vfio/vfio-cpr.h
+++ b/include/hw/vfio/vfio-cpr.h
@@ -67,7 +67,7 @@ bool vfio_cpr_container_match(struct VFIOContainer *container,
void vfio_cpr_giommu_remap(struct VFIOContainerBase *bcontainer,
MemoryRegionSection *section);
-bool vfio_cpr_ram_discard_register_listener(
+bool vfio_cpr_ram_discard_replay_populated(
struct VFIOContainerBase *bcontainer, MemoryRegionSection *section);
void vfio_cpr_save_vector_fd(struct VFIOPCIDevice *vdev, const char *name,
diff --git a/hw/vfio/cpr-legacy.c b/hw/vfio/cpr-legacy.c
index 553b203e9b..6909c0a616 100644
--- a/hw/vfio/cpr-legacy.c
+++ b/hw/vfio/cpr-legacy.c
@@ -224,22 +224,31 @@ void vfio_cpr_giommu_remap(VFIOContainerBase *bcontainer,
memory_region_iommu_replay(giommu->iommu_mr, &giommu->n);
}
+static int vfio_cpr_rdm_remap(MemoryRegionSection *section, void *opaque)
+{
+ RamDiscardListener *rdl = opaque;
+ return vfio_ram_discard_notify_populate(rdl, section);
+}
+
/*
* In old QEMU, VFIO_DMA_UNMAP_FLAG_VADDR may fail on some mapping after
* succeeding for others, so the latter have lost their vaddr. Call this
- * to restore vaddr for a section with a RamDiscardManager.
+ * to restore vaddr for populated parts in a section with a RamDiscardManager.
*
- * The ram discard listener already exists. Call its populate function
+ * The ram discard listener already exists. Call its replay_populated function
* directly, which calls vfio_legacy_cpr_dma_map.
*/
-bool vfio_cpr_ram_discard_register_listener(VFIOContainerBase *bcontainer,
- MemoryRegionSection *section)
+bool vfio_cpr_ram_discard_replay_populated(VFIOContainerBase *bcontainer,
+ MemoryRegionSection *section)
{
+ RamDiscardManager *rdm =
memory_region_get_ram_discard_manager(section->mr);
VFIORamDiscardListener *vrdl =
vfio_find_ram_discard_listener(bcontainer, section);
g_assert(vrdl);
- return vrdl->listener.notify_populate(&vrdl->listener, section) == 0;
+ return ram_discard_manager_replay_populated(rdm, section,
+ vfio_cpr_rdm_remap,
+ &vrdl->listener) == 0;
}
int vfio_cpr_group_get_device_fd(int d, const char *name)
diff --git a/hw/vfio/listener.c b/hw/vfio/listener.c
index f498e23a93..74837c1122 100644
--- a/hw/vfio/listener.c
+++ b/hw/vfio/listener.c
@@ -215,8 +215,8 @@ static void
vfio_ram_discard_notify_discard(RamDiscardListener *rdl,
}
}
-static int vfio_ram_discard_notify_populate(RamDiscardListener *rdl,
- MemoryRegionSection *section)
+int vfio_ram_discard_notify_populate(RamDiscardListener *rdl,
+ MemoryRegionSection *section)
{
VFIORamDiscardListener *vrdl = container_of(rdl, VFIORamDiscardListener,
listener);
@@ -572,8 +572,8 @@ void vfio_container_region_add(VFIOContainerBase
*bcontainer,
if (memory_region_has_ram_discard_manager(section->mr)) {
if (!cpr_remap) {
vfio_ram_discard_register_listener(bcontainer, section);
- } else if (!vfio_cpr_ram_discard_register_listener(bcontainer,
- section)) {
+ } else if (!vfio_cpr_ram_discard_replay_populated(bcontainer,
+ section)) {
goto fail;
}
return;
