[RFC V1 7/7] vdpa/cpr: preserve dma mappings

[Steve Sistare]

Preserve dma mappings during CPR restart by suppressing dma_map and
dma_unmap calls.  For devices with capability VHOST_BACKEND_F_IOTLB_REMAP,
convert dma_map calls to VHOST_IOTLB_REMAP to set the new userland VA for
the existing mapping.

However, map and unmap shadow vq buffers normally.  Their pages are not
locked in memory, and they are re-created after CPR.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 hw/virtio/trace-events        |  4 ++--
 hw/virtio/vhost-vdpa.c        | 30 +++++++++++++++++++++++++-----
 scripts/tracetool/__init__.py |  2 +-
 3 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
index 990c61be79..30d7f5ec69 100644
--- a/hw/virtio/trace-events
+++ b/hw/virtio/trace-events
@@ -31,8 +31,8 @@ vhost_user_create_notifier(int idx, void *n) "idx:%d n:%p"
 
 # vhost-vdpa.c
 vhost_vdpa_skipped_memory_section(int is_ram, int is_iommu, int is_protected, 
int is_ram_device, uint64_t first, uint64_t last, int page_mask) "is_ram=%d, 
is_iommu=%d, is_protected=%d, is_ram_device=%d iova_min=0x%"PRIx64" 
iova_last=0x%"PRIx64" page_mask=0x%x"
-vhost_vdpa_dma_map(void *vdpa, int fd, uint32_t msg_type, uint32_t asid, 
uint64_t iova, uint64_t size, uint64_t uaddr, uint8_t perm, uint8_t type) 
"vdpa_shared:%p fd: %d msg_type: %"PRIu32" asid: %"PRIu32" iova: 0x%"PRIx64" 
size: 0x%"PRIx64" uaddr: 0x%"PRIx64" perm: 0x%"PRIx8" type: %"PRIu8
-vhost_vdpa_dma_unmap(void *vdpa, int fd, uint32_t msg_type, uint32_t asid, 
uint64_t iova, uint64_t size, uint8_t type) "vdpa_shared:%p fd: %d msg_type: 
%"PRIu32" asid: %"PRIu32" iova: 0x%"PRIx64" size: 0x%"PRIx64" type: %"PRIu8
+vhost_vdpa_dma_map(void *vdpa, int fd, uint32_t msg_type, uint32_t asid, 
uint64_t iova, uint64_t size, uint64_t uaddr, uint8_t perm, uint8_t type, bool 
shadow, const char *override) "vdpa_shared:%p fd: %d msg_type: %"PRIu32" asid: 
%"PRIu32" iova: 0x%"PRIx64" size: 0x%"PRIx64" uaddr: 0x%"PRIx64" perm: 
0x%"PRIx8" type: %"PRIu8" shadow: %d %s"
+vhost_vdpa_dma_unmap(void *vdpa, int fd, uint32_t msg_type, uint32_t asid, 
uint64_t iova, uint64_t size, uint8_t type, bool shadow, const char *override) 
"vdpa_shared:%p fd: %d msg_type: %"PRIu32" asid: %"PRIu32" iova: 0x%"PRIx64" 
size: 0x%"PRIx64" type: %"PRIu8" shadow: %d %s"
 vhost_vdpa_listener_begin_batch(void *v, int fd, uint32_t msg_type, uint8_t 
type)  "vdpa_shared:%p fd: %d msg_type: %"PRIu32" type: %"PRIu8
 vhost_vdpa_listener_commit(void *v, int fd, uint32_t msg_type, uint8_t type)  
"vdpa_shared:%p fd: %d msg_type: %"PRIu32" type: %"PRIu8
 vhost_vdpa_listener_region_add_unaligned(void *v, const char *name, uint64_t 
offset_as, uint64_t offset_page) "vdpa_shared: %p region %s 
offset_within_address_space %"PRIu64" offset_within_region %"PRIu64
diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index d9ebc396b7..3ee809abfe 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -22,6 +22,8 @@
 #include "hw/virtio/vhost-vdpa.h"
 #include "exec/address-spaces.h"
 #include "migration/blocker.h"
+#include "migration/cpr.h"
+#include "migration/options.h"
 #include "qemu/cutils.h"
 #include "qemu/main-loop.h"
 #include "trace.h"
@@ -97,18 +99,29 @@ int vhost_vdpa_dma_map(VhostVDPAShared *s, uint32_t asid, 
hwaddr iova,
     struct vhost_msg_v2 msg = {};
     int fd = s->device_fd;
     int ret = 0;
+    bool remap = false, suppress = false;
+
+    if (migrate_mode() == MIG_MODE_CPR_EXEC && !shadow) {
+        remap = !!(s->backend_cap & BIT_ULL(VHOST_BACKEND_F_IOTLB_REMAP));
+        suppress = !remap;
+    }
 
     msg.type = VHOST_IOTLB_MSG_V2;
     msg.asid = asid;
     msg.iotlb.iova = iova;
     msg.iotlb.size = size;
     msg.iotlb.uaddr = (uint64_t)(uintptr_t)vaddr;
-    msg.iotlb.perm = readonly ? VHOST_ACCESS_RO : VHOST_ACCESS_RW;
-    msg.iotlb.type = VHOST_IOTLB_UPDATE;
+    msg.iotlb.perm = remap ? 0 : readonly ? VHOST_ACCESS_RO : VHOST_ACCESS_RW;
+    msg.iotlb.type = remap ? VHOST_IOTLB_REMAP : VHOST_IOTLB_UPDATE;
 
     trace_vhost_vdpa_dma_map(s, fd, msg.type, msg.asid, msg.iotlb.iova,
                              msg.iotlb.size, msg.iotlb.uaddr, msg.iotlb.perm,
-                             msg.iotlb.type);
+                             msg.iotlb.type, shadow,
+                             remap ? "(remap)" : suppress ? "(suppress)" : "");
+
+    if (suppress) {
+        return 0;
+    }
 
     if (write(fd, &msg, sizeof(msg)) != sizeof(msg)) {
         error_report("failed to write, fd=%d, errno=%d (%s)",
@@ -129,6 +142,7 @@ int vhost_vdpa_dma_unmap(VhostVDPAShared *s, uint32_t asid, 
hwaddr iova,
     struct vhost_msg_v2 msg = {};
     int fd = s->device_fd;
     int ret = 0;
+    bool suppress = migrate_mode() == MIG_MODE_CPR_EXEC && !shadow;
 
     msg.type = VHOST_IOTLB_MSG_V2;
     msg.asid = asid;
@@ -137,7 +151,12 @@ int vhost_vdpa_dma_unmap(VhostVDPAShared *s, uint32_t 
asid, hwaddr iova,
     msg.iotlb.type = VHOST_IOTLB_INVALIDATE;
 
     trace_vhost_vdpa_dma_unmap(s, fd, msg.type, msg.asid, msg.iotlb.iova,
-                               msg.iotlb.size, msg.iotlb.type);
+                               msg.iotlb.size, msg.iotlb.type, shadow,
+                               suppress ? "(suppressed)" : "");
+
+    if (suppress) {
+        return 0;
+    }
 
     if (write(fd, &msg, sizeof(msg)) != sizeof(msg)) {
         error_report("failed to write, fd=%d, errno=%d (%s)",
@@ -851,7 +870,8 @@ static int vhost_vdpa_set_backend_cap(struct vhost_dev *dev)
         0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH |
         0x1ULL << VHOST_BACKEND_F_IOTLB_ASID |
         0x1ULL << VHOST_BACKEND_F_SUSPEND |
-        0x1ULL << VHOST_BACKEND_F_NEW_OWNER;
+        0x1ULL << VHOST_BACKEND_F_NEW_OWNER |
+        0x1ULL << VHOST_BACKEND_F_IOTLB_REMAP;
     int r;
 
     if (vhost_vdpa_call(dev, VHOST_GET_BACKEND_FEATURES, &features)) {
diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py
index bc03238c0f..bfb181cb81 100644
--- a/scripts/tracetool/__init__.py
+++ b/scripts/tracetool/__init__.py
@@ -253,7 +253,7 @@ def __init__(self, name, props, fmt, args, lineno, 
filename, orig=None,
         self.event_trans = event_trans
         self.event_exec = event_exec
 
-        if len(args) > 10:
+        if len(args) > 11:
             raise ValueError("Event '%s' has more than maximum permitted "
                              "argument count" % name)
 
-- 
2.39.3