it will allow for other parts of QEMU check if it's safe
to map memory region during hotplug/runtime.
That way hotplug path will have a chance to cancel
hotplug operation instead of crashing in vhost_commit().
Signed-off-by: Igor Mammedov <imamm...@redhat.com>
---
v2:
* replace probbing with checking for
/sys/module/vhost/parameters/max_mem_regions and
if it's missing has non wrong value return
hardcoded legacy limit (64 slots).
---
hw/virtio/vhost-backend.c | 21 ++++++++++++++++++++-
hw/virtio/vhost-user.c | 8 +++++++-
hw/virtio/vhost.c | 21 +++++++++++++++++++++
include/hw/virtio/vhost-backend.h | 2 ++
include/hw/virtio/vhost.h | 1 +
stubs/Makefile.objs | 1 +
stubs/vhost.c | 6 ++++++
7 files changed, 58 insertions(+), 2 deletions(-)
create mode 100644 stubs/vhost.c
diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
index 4d68a27..11ec669 100644
--- a/hw/virtio/vhost-backend.c
+++ b/hw/virtio/vhost-backend.c
@@ -11,6 +11,7 @@
#include "hw/virtio/vhost.h"
#include "hw/virtio/vhost-backend.h"
#include "qemu/error-report.h"
+#include "linux/vhost.h"
#include <sys/ioctl.h>
@@ -42,11 +43,29 @@ static int vhost_kernel_cleanup(struct vhost_dev *dev)
return close(fd);
}
+static int vhost_kernel_memslots_limit(struct vhost_dev *dev)
+{
+ int limit = 64;
+ char *s;
+
+ if (g_file_get_contents("/sys/module/vhost/parameters/max_mem_regions",
+ &s, NULL, NULL)) {
+ uint64_t val = g_ascii_strtoull(s, NULL, 10);
+ if (!((val == G_MAXUINT64 || !val) && errno)) {
+ return val;
+ }
+ error_report("ignoring invalid max_mem_regions value in vhost module:"
+ " %s", s);
+ }
+ return limit;
+}
+
static const VhostOps kernel_ops = {
.backend_type = VHOST_BACKEND_TYPE_KERNEL,
.vhost_call = vhost_kernel_call,
.vhost_backend_init = vhost_kernel_init,
- .vhost_backend_cleanup = vhost_kernel_cleanup
+ .vhost_backend_cleanup = vhost_kernel_cleanup,
+ .vhost_backend_memslots_limit = vhost_kernel_memslots_limit
};
int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType
backend_type)
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index e7ab829..acdfd04 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -343,9 +343,15 @@ static int vhost_user_cleanup(struct vhost_dev *dev)
return 0;
}
+static int vhost_user_memslots_limit(struct vhost_dev *dev)
+{
+ return VHOST_MEMORY_MAX_NREGIONS;
+}
+
const VhostOps user_ops = {
.backend_type = VHOST_BACKEND_TYPE_USER,
.vhost_call = vhost_user_call,
.vhost_backend_init = vhost_user_init,
- .vhost_backend_cleanup = vhost_user_cleanup
+ .vhost_backend_cleanup = vhost_user_cleanup,
+ .vhost_backend_memslots_limit = vhost_user_memslots_limit
};
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 2712c6f..e964004 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -26,6 +26,18 @@
static struct vhost_log *vhost_log;
+static int used_memslots;
+static int memslots_limit = -1;
+
+bool vhost_has_free_slot(void)
+{
+ if (memslots_limit >= 0) {
+ return memslots_limit > used_memslots;
+ }
+
+ return true;
+}
+
static void vhost_dev_sync_region(struct vhost_dev *dev,
MemoryRegionSection *section,
uint64_t mfirst, uint64_t mlast,
@@ -457,6 +469,7 @@ static void vhost_set_memory(MemoryListener *listener,
dev->mem_changed_start_addr = MIN(dev->mem_changed_start_addr, start_addr);
dev->mem_changed_end_addr = MAX(dev->mem_changed_end_addr, start_addr +
size - 1);
dev->memory_changed = true;
+ used_memslots = dev->mem->nregions;
}
static bool vhost_section(MemoryRegionSection *section)
@@ -1119,6 +1132,14 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice
*vdev)
if (r < 0) {
goto fail_features;
}
+
+ r = hdev->vhost_ops->vhost_backend_memslots_limit(hdev);
+ if (memslots_limit > 0) {
+ memslots_limit = MIN(memslots_limit, r);
+ } else {
+ memslots_limit = r;
+ }
+
r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_MEM_TABLE, hdev->mem);
if (r < 0) {
r = -errno;
diff --git a/include/hw/virtio/vhost-backend.h
b/include/hw/virtio/vhost-backend.h
index e472f29..28b6714 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -24,12 +24,14 @@ typedef int (*vhost_call)(struct vhost_dev *dev, unsigned
long int request,
void *arg);
typedef int (*vhost_backend_init)(struct vhost_dev *dev, void *opaque);
typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev);
+typedef int (*vhost_backend_memslots_limit)(struct vhost_dev *dev);
typedef struct VhostOps {
VhostBackendType backend_type;
vhost_call vhost_call;
vhost_backend_init vhost_backend_init;
vhost_backend_cleanup vhost_backend_cleanup;
+ vhost_backend_memslots_limit vhost_backend_memslots_limit;
} VhostOps;
extern const VhostOps user_ops;
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index dd51050..17ff7b6 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -81,4 +81,5 @@ uint64_t vhost_get_features(struct vhost_dev *hdev, const int
*feature_bits,
uint64_t features);
void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits,
uint64_t features);
+bool vhost_has_free_slot(void);
#endif
diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
index 9937a12..d2f1b21 100644
--- a/stubs/Makefile.objs
+++ b/stubs/Makefile.objs
@@ -38,3 +38,4 @@ stub-obj-$(CONFIG_WIN32) += fd-register.o
stub-obj-y += cpus.o
stub-obj-y += kvm.o
stub-obj-y += qmp_pc_dimm_device_list.o
+stub-obj-y += vhost.o
diff --git a/stubs/vhost.c b/stubs/vhost.c
new file mode 100644
index 0000000..d346b85
--- /dev/null
+++ b/stubs/vhost.c
@@ -0,0 +1,6 @@
+#include "hw/virtio/vhost.h"
+
+bool vhost_has_free_slot(void)
+{
+ return true;
+}
--
1.8.3.1
