@@ -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>
@@ -49,12 +50,30 @@ static int vhost_kernel_get_vq_index(struct vhost_dev *dev, int idx)
return idx - dev->vq_index;
}
+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_get_vq_index = vhost_kernel_get_vq_index,
+ .vhost_backend_memslots_limit = vhost_kernel_memslots_limit,
};
int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType backend_type)
@@ -440,6 +440,11 @@ static int vhost_user_get_vq_index(struct vhost_dev *dev, int idx)
return idx;
}
+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,
@@ -447,4 +452,5 @@ const VhostOps user_ops = {
.vhost_backend_cleanup = vhost_user_cleanup,
.vhost_backend_get_vq_index = vhost_user_get_vq_index,
.vhost_backend_set_vring_enable = vhost_user_set_vring_enable,
+ .vhost_backend_memslots_limit = vhost_user_memslots_limit,
};
@@ -26,6 +26,22 @@
static struct vhost_log *vhost_log;
+static unsigned int used_memslots;
+static QLIST_HEAD(, vhost_dev) vhost_devices =
+ QLIST_HEAD_INITIALIZER(vhost_devices);
+
+bool vhost_has_free_slot(void)
+{
+ unsigned int slots_limit = ~0U;
+ struct vhost_dev *hdev;
+
+ QLIST_FOREACH(hdev, &vhost_devices, entry) {
+ unsigned int r = hdev->vhost_ops->vhost_backend_memslots_limit(hdev);
+ slots_limit = MIN(slots_limit, r);
+ }
+ return slots_limit > used_memslots;
+}
+
static void vhost_dev_sync_region(struct vhost_dev *dev,
MemoryRegionSection *section,
uint64_t mfirst, uint64_t mlast,
@@ -457,6 +473,7 @@ 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)
@@ -916,6 +933,8 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
return -errno;
}
+ QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
+
r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_OWNER, NULL);
if (r < 0) {
goto fail;
@@ -972,6 +991,7 @@ fail_vq:
fail:
r = -errno;
hdev->vhost_ops->vhost_backend_cleanup(hdev);
+ QLIST_REMOVE(hdev, entry);
return r;
}
@@ -989,6 +1009,7 @@ void vhost_dev_cleanup(struct vhost_dev *hdev)
g_free(hdev->mem);
g_free(hdev->mem_sections);
hdev->vhost_ops->vhost_backend_cleanup(hdev);
+ QLIST_REMOVE(hdev, entry);
}
/* Stop processing guest IO notifications in qemu.
@@ -26,6 +26,7 @@ typedef int (*vhost_backend_init)(struct vhost_dev *dev, void *opaque);
typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev);
typedef int (*vhost_backend_get_vq_index)(struct vhost_dev *dev, int idx);
typedef int (*vhost_backend_set_vring_enable)(struct vhost_dev *dev, int enable);
+typedef int (*vhost_backend_memslots_limit)(struct vhost_dev *dev);
typedef struct VhostOps {
VhostBackendType backend_type;
@@ -34,6 +35,7 @@ typedef struct VhostOps {
vhost_backend_cleanup vhost_backend_cleanup;
vhost_backend_get_vq_index vhost_backend_get_vq_index;
vhost_backend_set_vring_enable vhost_backend_set_vring_enable;
+ vhost_backend_memslots_limit vhost_backend_memslots_limit;
} VhostOps;
extern const VhostOps user_ops;
@@ -59,6 +59,7 @@ struct vhost_dev {
const VhostOps *vhost_ops;
void *opaque;
struct vhost_log *log;
+ QLIST_ENTRY(vhost_dev) entry;
};
int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
@@ -83,4 +84,5 @@ 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
@@ -39,3 +39,4 @@ stub-obj-y += cpus.o
stub-obj-y += kvm.o
stub-obj-y += qmp_pc_dimm_device_list.o
stub-obj-y += target-monitor-defs.o
+stub-obj-y += vhost.o
new file mode 100644
@@ -0,0 +1,6 @@
+#include "hw/virtio/vhost.h"
+
+bool vhost_has_free_slot(void)
+{
+ return true;
+}
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 <imammedo@redhat.com> --- v4: * rescan all vhost backends when checking for limit (Michael S. Tsirkin) v3: * add refcountin of limit by # vhost devices, and make vhost_has_free_slot() return true if no vhost devices are present at current moment * move limit initialization to vhost_dev_init() 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). fixup1 --- hw/virtio/vhost-backend.c | 19 +++++++++++++++++++ hw/virtio/vhost-user.c | 6 ++++++ hw/virtio/vhost.c | 21 +++++++++++++++++++++ include/hw/virtio/vhost-backend.h | 2 ++ include/hw/virtio/vhost.h | 2 ++ stubs/Makefile.objs | 1 + stubs/vhost.c | 6 ++++++ 7 files changed, 57 insertions(+) create mode 100644 stubs/vhost.c