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* [PATCH] vhost-user: add separate memslot counter for vhost-user
@ 2020-09-28 13:17 Jiajun Chen
  2020-10-02  2:05 ` Raphael Norwitz
                   ` (2 more replies)
  0 siblings, 3 replies; 23+ messages in thread
From: Jiajun Chen @ 2020-09-28 13:17 UTC (permalink / raw)
  To: raphael.s.norwitz
  Cc: zhang.zhanghailiang, mst, jasowang, qemu-devel, xiexiangyou,
	imammedo, marcandre.lureau

Used_memslots is equal to dev->mem->nregions now, it is true for
vhost kernel, but not for vhost user, which uses the memory regions
that have file descriptor. In fact, not all of the memory regions
have file descriptor.
It is usefully in some scenarios, e.g. used_memslots is 8, and only
5 memory slots can be used by vhost user, it is failed to hot plug
a new memory RAM because vhost_has_free_slot just returned false,
but we can hot plug it safely in fact.

--
ChangeList:
v3:
-make used_memslots a member of struct vhost_dev instead of a global static value

v2:
-eliminating useless used_memslots_exceeded variable and used_memslots_is_exceeded() API

v1:
-vhost-user: add separate memslot counter for vhost-user

Signed-off-by: Jiajun Chen <chenjiajun8@huawei.com>
Signed-off-by: Jianjay Zhou <jianjay.zhou@huawei.com>
---
 hw/virtio/vhost-backend.c         | 12 ++++++++++
 hw/virtio/vhost-user.c            | 25 +++++++++++++++++++++
 hw/virtio/vhost.c                 | 37 +++++++++++++++++++++++--------
 include/hw/virtio/vhost-backend.h |  5 +++++
 include/hw/virtio/vhost.h         |  1 +
 net/vhost-user.c                  |  7 ++++++
 6 files changed, 78 insertions(+), 9 deletions(-)

diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
index 782b1d67d9..7016f23ec5 100644
--- a/hw/virtio/vhost-backend.c
+++ b/hw/virtio/vhost-backend.c
@@ -238,6 +238,16 @@ static void vhost_kernel_set_iotlb_callback(struct vhost_dev *dev,
         qemu_set_fd_handler((uintptr_t)dev->opaque, NULL, NULL, NULL);
 }
 
+static void vhost_kernel_set_used_memslots(struct vhost_dev *dev)
+{
+    dev->used_memslots = dev->mem->nregions;
+}
+
+static unsigned int vhost_kernel_get_used_memslots(struct vhost_dev *dev)
+{
+    return dev->used_memslots;
+}
+
 static const VhostOps kernel_ops = {
         .backend_type = VHOST_BACKEND_TYPE_KERNEL,
         .vhost_backend_init = vhost_kernel_init,
@@ -269,6 +279,8 @@ static const VhostOps kernel_ops = {
 #endif /* CONFIG_VHOST_VSOCK */
         .vhost_set_iotlb_callback = vhost_kernel_set_iotlb_callback,
         .vhost_send_device_iotlb_msg = vhost_kernel_send_device_iotlb_msg,
+        .vhost_set_used_memslots = vhost_kernel_set_used_memslots,
+        .vhost_get_used_memslots = vhost_kernel_get_used_memslots,
 };
 #endif
 
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 31231218dc..5dea64d8a8 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -2354,6 +2354,29 @@ void vhost_user_cleanup(VhostUserState *user)
     user->chr = NULL;
 }
 
+static void vhost_user_set_used_memslots(struct vhost_dev *dev)
+{
+    int i;
+    dev->used_memslots = 0;
+
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        ram_addr_t offset;
+        MemoryRegion *mr;
+        int fd;
+
+        mr = vhost_user_get_mr_data(reg->userspace_addr, &offset, &fd);
+        if (mr && fd > 0) {
+            dev->used_memslots++;
+        }
+    }
+}
+
+static unsigned int vhost_user_get_used_memslots(struct vhost_dev *dev)
+{
+    return dev->used_memslots;
+}
+
 const VhostOps user_ops = {
         .backend_type = VHOST_BACKEND_TYPE_USER,
         .vhost_backend_init = vhost_user_backend_init,
@@ -2387,4 +2410,6 @@ const VhostOps user_ops = {
         .vhost_backend_mem_section_filter = vhost_user_mem_section_filter,
         .vhost_get_inflight_fd = vhost_user_get_inflight_fd,
         .vhost_set_inflight_fd = vhost_user_set_inflight_fd,
+        .vhost_set_used_memslots = vhost_user_set_used_memslots,
+        .vhost_get_used_memslots = vhost_user_get_used_memslots,
 };
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 1a1384e7a6..98b967669b 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -45,20 +45,20 @@
 static struct vhost_log *vhost_log;
 static struct vhost_log *vhost_log_shm;
 
-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);
+        if (hdev->vhost_ops->vhost_get_used_memslots(hdev) >=
+            hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+            return false;
+        }
     }
-    return slots_limit > used_memslots;
+    return true;
 }
 
 static void vhost_dev_sync_region(struct vhost_dev *dev,
@@ -502,7 +502,6 @@ static void vhost_commit(MemoryListener *listener)
                        dev->n_mem_sections * sizeof dev->mem->regions[0];
     dev->mem = g_realloc(dev->mem, regions_size);
     dev->mem->nregions = dev->n_mem_sections;
-    used_memslots = dev->mem->nregions;
     for (i = 0; i < dev->n_mem_sections; i++) {
         struct vhost_memory_region *cur_vmr = dev->mem->regions + i;
         struct MemoryRegionSection *mrs = dev->mem_sections + i;
@@ -678,6 +677,7 @@ static void vhost_region_add_section(struct vhost_dev *dev,
         dev->tmp_sections[dev->n_tmp_sections - 1].fv = NULL;
         memory_region_ref(section->mr);
     }
+    dev->vhost_ops->vhost_set_used_memslots(dev);
 }
 
 /* Used for both add and nop callbacks */
@@ -693,6 +693,17 @@ static void vhost_region_addnop(MemoryListener *listener,
     vhost_region_add_section(dev, section);
 }
 
+static void vhost_region_del(MemoryListener *listener,
+                             MemoryRegionSection *section)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         memory_listener);
+    if (!vhost_section(dev, section)) {
+        return;
+    }
+    dev->vhost_ops->vhost_set_used_memslots(dev);
+}
+
 static void vhost_iommu_unmap_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
 {
     struct vhost_iommu *iommu = container_of(n, struct vhost_iommu, n);
@@ -1300,6 +1311,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     hdev->memory_listener = (MemoryListener) {
         .begin = vhost_begin,
         .commit = vhost_commit,
+        .region_del = vhost_region_del,
         .region_add = vhost_region_addnop,
         .region_nop = vhost_region_addnop,
         .log_start = vhost_log_start,
@@ -1346,9 +1358,16 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     memory_listener_register(&hdev->memory_listener, &address_space_memory);
     QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
 
-    if (used_memslots > hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
-        error_report("vhost backend memory slots limit is less"
-                " than current number of present memory slots");
+    /*
+     * If we started a VM without any vhost device,
+     * for the first time vhost device hot-plug
+     * (vhost_get_used_memslots is always 0),
+     * so it needs to double check here.
+     */
+    if (hdev->vhost_ops->vhost_get_used_memslots(hdev) >
+        hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+        error_report("vhost backend memory slots limit is less than"
+                     " current number of present memory slots");
         r = -1;
         if (busyloop_timeout) {
             goto fail_busyloop;
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index 8825bd278f..6569c95a43 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -124,6 +124,9 @@ typedef int (*vhost_get_device_id_op)(struct vhost_dev *dev, uint32_t *dev_id);
 
 typedef bool (*vhost_force_iommu_op)(struct vhost_dev *dev);
 
+typedef void (*vhost_set_used_memslots_op)(struct vhost_dev *dev);
+typedef unsigned int (*vhost_get_used_memslots_op)(struct vhost_dev *dev);
+
 typedef struct VhostOps {
     VhostBackendType backend_type;
     vhost_backend_init vhost_backend_init;
@@ -168,6 +171,8 @@ typedef struct VhostOps {
     vhost_vq_get_addr_op  vhost_vq_get_addr;
     vhost_get_device_id_op vhost_get_device_id;
     vhost_force_iommu_op vhost_force_iommu;
+    vhost_set_used_memslots_op vhost_set_used_memslots;
+    vhost_get_used_memslots_op vhost_get_used_memslots;
 } VhostOps;
 
 extern const VhostOps user_ops;
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 767a95ec0b..5ded21f86d 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -90,6 +90,7 @@ struct vhost_dev {
     QLIST_HEAD(, vhost_iommu) iommu_list;
     IOMMUNotifier n;
     const VhostDevConfigOps *config_ops;
+    unsigned int used_memslots;
 };
 
 struct vhost_net {
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 17532daaf3..7e93955537 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -20,6 +20,7 @@
 #include "qemu/error-report.h"
 #include "qemu/option.h"
 #include "trace.h"
+#include "include/hw/virtio/vhost.h"
 
 typedef struct NetVhostUserState {
     NetClientState nc;
@@ -347,6 +348,12 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
         qemu_chr_fe_set_handlers(&s->chr, NULL, NULL,
                                  net_vhost_user_event, NULL, nc0->name, NULL,
                                  true);
+
+        if (!vhost_has_free_slot()) {
+            error_report("used memslots exceeded the backend limit, quit "
+                         "loop");
+            goto err;
+        }
     } while (!s->started);
 
     assert(s->vhost_net);
-- 
2.27.0.dirty



^ permalink raw reply related	[flat|nested] 23+ messages in thread
* [PATCH] vhost-user: add separate memslot counter for vhost-user
@ 2020-09-08  6:11 Jiajun Chen
  2020-09-08  8:37 ` Michael S. Tsirkin
  2020-09-15  1:27 ` Raphael Norwitz
  0 siblings, 2 replies; 23+ messages in thread
From: Jiajun Chen @ 2020-09-08  6:11 UTC (permalink / raw)
  To: raphael.s.norwitz
  Cc: zhang.zhanghailiang, jasowang, qemu-devel, xiexiangyou, mst

Used_memslots is equal to dev->mem->nregions now, it is true for
vhost kernel, but not for vhost user, which uses the memory regions
that have file descriptor. In fact, not all of the memory regions
have file descriptor.
It is usefully in some scenarios, e.g. used_memslots is 8, and only
5 memory slots can be used by vhost user, it is failed to hot plug
a new memory RAM because vhost_has_free_slot just returned false,
but we can hot plug it safely in fact.

--
ChangeList:
v2:
-eliminating useless used_memslots_exceeded variable and used_memslots_is_exceeded() API

v1:
-vhost-user: add separate memslot counter for vhost-user

Signed-off-by: Jiajun Chen <chenjiajun8@huawei.com>
Signed-off-by: Jianjay Zhou <jianjay.zhou@huawei.com>
---
 hw/virtio/vhost-backend.c         | 14 ++++++++++++
 hw/virtio/vhost-user.c            | 28 +++++++++++++++++++++++
 hw/virtio/vhost.c                 | 37 +++++++++++++++++++++++--------
 include/hw/virtio/vhost-backend.h |  5 +++++
 net/vhost-user.c                  |  7 ++++++
 5 files changed, 82 insertions(+), 9 deletions(-)

diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
index 782b1d67d9..35eec7e166 100644
--- a/hw/virtio/vhost-backend.c
+++ b/hw/virtio/vhost-backend.c
@@ -20,6 +20,8 @@
 #include <linux/vhost.h>
 #include <sys/ioctl.h>
 
+static unsigned int vhost_kernel_used_memslots;
+
 static int vhost_kernel_call(struct vhost_dev *dev, unsigned long int request,
                              void *arg)
 {
@@ -238,6 +240,16 @@ static void vhost_kernel_set_iotlb_callback(struct vhost_dev *dev,
         qemu_set_fd_handler((uintptr_t)dev->opaque, NULL, NULL, NULL);
 }
 
+static void vhost_kernel_set_used_memslots(struct vhost_dev *dev)
+{
+    vhost_kernel_used_memslots = dev->mem->nregions;
+}
+
+static unsigned int vhost_kernel_get_used_memslots(void)
+{
+    return vhost_kernel_used_memslots;
+}
+
 static const VhostOps kernel_ops = {
         .backend_type = VHOST_BACKEND_TYPE_KERNEL,
         .vhost_backend_init = vhost_kernel_init,
@@ -269,6 +281,8 @@ static const VhostOps kernel_ops = {
 #endif /* CONFIG_VHOST_VSOCK */
         .vhost_set_iotlb_callback = vhost_kernel_set_iotlb_callback,
         .vhost_send_device_iotlb_msg = vhost_kernel_send_device_iotlb_msg,
+        .vhost_set_used_memslots = vhost_kernel_set_used_memslots,
+        .vhost_get_used_memslots = vhost_kernel_get_used_memslots,
 };
 #endif
 
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 31231218dc..ec46a745fa 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -232,6 +232,7 @@ static VhostUserMsg m __attribute__ ((unused));
 
 /* The version of the protocol we support */
 #define VHOST_USER_VERSION    (0x1)
+static unsigned int vhost_user_used_memslots;
 
 struct vhost_user {
     struct vhost_dev *dev;
@@ -2354,6 +2355,31 @@ void vhost_user_cleanup(VhostUserState *user)
     user->chr = NULL;
 }
 
+static void vhost_user_set_used_memslots(struct vhost_dev *dev)
+{
+    unsigned int counter = 0;
+    int i;
+
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        ram_addr_t offset;
+        MemoryRegion *mr;
+        int fd;
+
+        assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
+        mr = vhost_user_get_mr_data(reg->userspace_addr, &offset, &fd);
+        if (mr && fd > 0) {
+            counter++;
+        }
+    }
+    vhost_user_used_memslots = counter;
+}
+
+static unsigned int vhost_user_get_used_memslots(void)
+{
+    return vhost_user_used_memslots;
+}
+
 const VhostOps user_ops = {
         .backend_type = VHOST_BACKEND_TYPE_USER,
         .vhost_backend_init = vhost_user_backend_init,
@@ -2387,4 +2413,6 @@ const VhostOps user_ops = {
         .vhost_backend_mem_section_filter = vhost_user_mem_section_filter,
         .vhost_get_inflight_fd = vhost_user_get_inflight_fd,
         .vhost_set_inflight_fd = vhost_user_set_inflight_fd,
+        .vhost_set_used_memslots = vhost_user_set_used_memslots,
+        .vhost_get_used_memslots = vhost_user_get_used_memslots,
 };
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 1a1384e7a6..b8d617d24c 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -45,20 +45,20 @@
 static struct vhost_log *vhost_log;
 static struct vhost_log *vhost_log_shm;
 
-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);
+        if (hdev->vhost_ops->vhost_get_used_memslots() >=
+            hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+            return false;
+        }
     }
-    return slots_limit > used_memslots;
+    return true;
 }
 
 static void vhost_dev_sync_region(struct vhost_dev *dev,
@@ -502,7 +502,6 @@ static void vhost_commit(MemoryListener *listener)
                        dev->n_mem_sections * sizeof dev->mem->regions[0];
     dev->mem = g_realloc(dev->mem, regions_size);
     dev->mem->nregions = dev->n_mem_sections;
-    used_memslots = dev->mem->nregions;
     for (i = 0; i < dev->n_mem_sections; i++) {
         struct vhost_memory_region *cur_vmr = dev->mem->regions + i;
         struct MemoryRegionSection *mrs = dev->mem_sections + i;
@@ -678,6 +677,7 @@ static void vhost_region_add_section(struct vhost_dev *dev,
         dev->tmp_sections[dev->n_tmp_sections - 1].fv = NULL;
         memory_region_ref(section->mr);
     }
+    dev->vhost_ops->vhost_set_used_memslots(dev);
 }
 
 /* Used for both add and nop callbacks */
@@ -693,6 +693,17 @@ static void vhost_region_addnop(MemoryListener *listener,
     vhost_region_add_section(dev, section);
 }
 
+static void vhost_region_del(MemoryListener *listener,
+                             MemoryRegionSection *section)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         memory_listener);
+    if (!vhost_section(dev, section)) {
+        return;
+    }
+    dev->vhost_ops->vhost_set_used_memslots(dev);
+}
+
 static void vhost_iommu_unmap_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
 {
     struct vhost_iommu *iommu = container_of(n, struct vhost_iommu, n);
@@ -1300,6 +1311,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     hdev->memory_listener = (MemoryListener) {
         .begin = vhost_begin,
         .commit = vhost_commit,
+        .region_del = vhost_region_del,
         .region_add = vhost_region_addnop,
         .region_nop = vhost_region_addnop,
         .log_start = vhost_log_start,
@@ -1346,9 +1358,16 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     memory_listener_register(&hdev->memory_listener, &address_space_memory);
     QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
 
-    if (used_memslots > hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
-        error_report("vhost backend memory slots limit is less"
-                " than current number of present memory slots");
+    /*
+     * If we started a VM without any vhost device,
+     * for the first time vhost device hot-plug
+     * (vhost_get_used_memslots is always 0),
+     * so it needs to double check here
+     */
+    if (hdev->vhost_ops->vhost_get_used_memslots() >
+        hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+        error_report("vhost backend memory slots limit is less than"
+                     " current number of present memory slots");
         r = -1;
         if (busyloop_timeout) {
             goto fail_busyloop;
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index 8825bd278f..ed43a93692 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -124,6 +124,9 @@ typedef int (*vhost_get_device_id_op)(struct vhost_dev *dev, uint32_t *dev_id);
 
 typedef bool (*vhost_force_iommu_op)(struct vhost_dev *dev);
 
+typedef void (*vhost_set_used_memslots_op)(struct vhost_dev *dev);
+typedef unsigned int (*vhost_get_used_memslots_op)(void);
+
 typedef struct VhostOps {
     VhostBackendType backend_type;
     vhost_backend_init vhost_backend_init;
@@ -168,6 +171,8 @@ typedef struct VhostOps {
     vhost_vq_get_addr_op  vhost_vq_get_addr;
     vhost_get_device_id_op vhost_get_device_id;
     vhost_force_iommu_op vhost_force_iommu;
+    vhost_set_used_memslots_op vhost_set_used_memslots;
+    vhost_get_used_memslots_op vhost_get_used_memslots;
 } VhostOps;
 
 extern const VhostOps user_ops;
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 17532daaf3..7e93955537 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -20,6 +20,7 @@
 #include "qemu/error-report.h"
 #include "qemu/option.h"
 #include "trace.h"
+#include "include/hw/virtio/vhost.h"
 
 typedef struct NetVhostUserState {
     NetClientState nc;
@@ -347,6 +348,12 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
         qemu_chr_fe_set_handlers(&s->chr, NULL, NULL,
                                  net_vhost_user_event, NULL, nc0->name, NULL,
                                  true);
+
+        if (!vhost_has_free_slot()) {
+            error_report("used memslots exceeded the backend limit, quit "
+                         "loop");
+            goto err;
+        }
     } while (!s->started);
 
     assert(s->vhost_net);
-- 
2.19.1



^ permalink raw reply related	[flat|nested] 23+ messages in thread
* [PATCH] vhost-user: add separate memslot counter for vhost-user
@ 2020-08-11  1:43 Jiajun Chen
  2020-08-27 12:11 ` Michael S. Tsirkin
  2020-09-02  5:02 ` Raphael Norwitz
  0 siblings, 2 replies; 23+ messages in thread
From: Jiajun Chen @ 2020-08-11  1:43 UTC (permalink / raw)
  To: mst, jasowang; +Cc: qemu-devel, xiexiangyou, zhang.zhanghailiang

Used_memslots is equal to dev->mem->nregions now, it is true for
vhost kernel, but not for vhost user, which uses the memory regions
that have file descriptor. In fact, not all of the memory regions
have file descriptor.
It is usefully in some scenarios, e.g. used_memslots is 8, and only
5 memory slots can be used by vhost user, it is failed to hot plug
a new memory RAM because vhost_has_free_slot just returned false,
but we can hot plug it safely in fact.

Signed-off-by: Jiajun Chen <chenjiajun8@huawei.com>
Signed-off-by: Jianjay Zhou <jianjay.zhou@huawei.com>
---
 hw/virtio/vhost-backend.c         | 14 ++++++++
 hw/virtio/vhost-user.c            | 28 ++++++++++++++++
 hw/virtio/vhost.c                 | 54 +++++++++++++++++++++++++------
 include/hw/virtio/vhost-backend.h |  5 +++
 include/hw/virtio/vhost.h         |  1 +
 net/vhost-user.c                  |  7 ++++
 6 files changed, 100 insertions(+), 9 deletions(-)

diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
index 782b1d67d9..35eec7e166 100644
--- a/hw/virtio/vhost-backend.c
+++ b/hw/virtio/vhost-backend.c
@@ -20,6 +20,8 @@
 #include <linux/vhost.h>
 #include <sys/ioctl.h>
 
+static unsigned int vhost_kernel_used_memslots;
+
 static int vhost_kernel_call(struct vhost_dev *dev, unsigned long int request,
                              void *arg)
 {
@@ -238,6 +240,16 @@ static void vhost_kernel_set_iotlb_callback(struct vhost_dev *dev,
         qemu_set_fd_handler((uintptr_t)dev->opaque, NULL, NULL, NULL);
 }
 
+static void vhost_kernel_set_used_memslots(struct vhost_dev *dev)
+{
+    vhost_kernel_used_memslots = dev->mem->nregions;
+}
+
+static unsigned int vhost_kernel_get_used_memslots(void)
+{
+    return vhost_kernel_used_memslots;
+}
+
 static const VhostOps kernel_ops = {
         .backend_type = VHOST_BACKEND_TYPE_KERNEL,
         .vhost_backend_init = vhost_kernel_init,
@@ -269,6 +281,8 @@ static const VhostOps kernel_ops = {
 #endif /* CONFIG_VHOST_VSOCK */
         .vhost_set_iotlb_callback = vhost_kernel_set_iotlb_callback,
         .vhost_send_device_iotlb_msg = vhost_kernel_send_device_iotlb_msg,
+        .vhost_set_used_memslots = vhost_kernel_set_used_memslots,
+        .vhost_get_used_memslots = vhost_kernel_get_used_memslots,
 };
 #endif
 
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 31231218dc..04d20fc3ee 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -232,6 +232,7 @@ static VhostUserMsg m __attribute__ ((unused));
 
 /* The version of the protocol we support */
 #define VHOST_USER_VERSION    (0x1)
+static unsigned int vhost_user_used_memslots;
 
 struct vhost_user {
     struct vhost_dev *dev;
@@ -2354,6 +2355,31 @@ void vhost_user_cleanup(VhostUserState *user)
     user->chr = NULL;
 }
 
+static void vhost_user_set_used_memslots(struct vhost_dev *dev)
+{
+    unsigned int counter = 0;
+    int i;
+
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        ram_addr_t offset;
+        MemoryRegion *mr;
+
+        assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
+        mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
+                                    &offset);
+        if (mr && memory_region_get_fd(mr) > 0) {
+            counter++;
+        }
+    }
+    vhost_user_used_memslots = counter;
+}
+
+static unsigned int vhost_user_get_used_memslots(void)
+{
+    return vhost_user_used_memslots;
+}
+
 const VhostOps user_ops = {
         .backend_type = VHOST_BACKEND_TYPE_USER,
         .vhost_backend_init = vhost_user_backend_init,
@@ -2387,4 +2413,6 @@ const VhostOps user_ops = {
         .vhost_backend_mem_section_filter = vhost_user_mem_section_filter,
         .vhost_get_inflight_fd = vhost_user_get_inflight_fd,
         .vhost_set_inflight_fd = vhost_user_set_inflight_fd,
+        .vhost_set_used_memslots = vhost_user_set_used_memslots,
+        .vhost_get_used_memslots = vhost_user_get_used_memslots,
 };
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 1a1384e7a6..7f36d7af25 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -45,20 +45,22 @@
 static struct vhost_log *vhost_log;
 static struct vhost_log *vhost_log_shm;
 
-static unsigned int used_memslots;
 static QLIST_HEAD(, vhost_dev) vhost_devices =
     QLIST_HEAD_INITIALIZER(vhost_devices);
 
+bool used_memslots_exceeded;
+
 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);
+        if (hdev->vhost_ops->vhost_get_used_memslots() >=
+            hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+            return false;
+        }
     }
-    return slots_limit > used_memslots;
+    return true;
 }
 
 static void vhost_dev_sync_region(struct vhost_dev *dev,
@@ -502,7 +504,6 @@ static void vhost_commit(MemoryListener *listener)
                        dev->n_mem_sections * sizeof dev->mem->regions[0];
     dev->mem = g_realloc(dev->mem, regions_size);
     dev->mem->nregions = dev->n_mem_sections;
-    used_memslots = dev->mem->nregions;
     for (i = 0; i < dev->n_mem_sections; i++) {
         struct vhost_memory_region *cur_vmr = dev->mem->regions + i;
         struct MemoryRegionSection *mrs = dev->mem_sections + i;
@@ -678,6 +679,7 @@ static void vhost_region_add_section(struct vhost_dev *dev,
         dev->tmp_sections[dev->n_tmp_sections - 1].fv = NULL;
         memory_region_ref(section->mr);
     }
+    dev->vhost_ops->vhost_set_used_memslots(dev);
 }
 
 /* Used for both add and nop callbacks */
@@ -693,6 +695,17 @@ static void vhost_region_addnop(MemoryListener *listener,
     vhost_region_add_section(dev, section);
 }
 
+static void vhost_region_del(MemoryListener *listener,
+                             MemoryRegionSection *section)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         memory_listener);
+    if (!vhost_section(dev, section)) {
+        return;
+    }
+    dev->vhost_ops->vhost_set_used_memslots(dev);
+}
+
 static void vhost_iommu_unmap_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
 {
     struct vhost_iommu *iommu = container_of(n, struct vhost_iommu, n);
@@ -1248,6 +1261,19 @@ static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
     event_notifier_cleanup(&vq->masked_notifier);
 }
 
+static bool vhost_dev_used_memslots_is_exceeded(struct vhost_dev *hdev)
+{
+    if (hdev->vhost_ops->vhost_get_used_memslots() >
+        hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+        error_report("vhost backend memory slots limit is less"
+                " than current number of present memory slots");
+        used_memslots_exceeded = true;
+        return true;
+    }
+    used_memslots_exceeded = false;
+    return false;
+}
+
 int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
                    VhostBackendType backend_type, uint32_t busyloop_timeout)
 {
@@ -1300,6 +1326,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     hdev->memory_listener = (MemoryListener) {
         .begin = vhost_begin,
         .commit = vhost_commit,
+        .region_del = vhost_region_del,
         .region_add = vhost_region_addnop,
         .region_nop = vhost_region_addnop,
         .log_start = vhost_log_start,
@@ -1346,9 +1373,13 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     memory_listener_register(&hdev->memory_listener, &address_space_memory);
     QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
 
-    if (used_memslots > hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
-        error_report("vhost backend memory slots limit is less"
-                " than current number of present memory slots");
+    /*
+     * If we started a VM without any vhost device,
+     * vhost_dev_used_memslots_is_exceeded will always return false for the
+     * first time vhost device hot-plug(vhost_get_used_memslots is always 0),
+     * so it needs to double check here
+     */
+    if (vhost_dev_used_memslots_is_exceeded(hdev)) {
         r = -1;
         if (busyloop_timeout) {
             goto fail_busyloop;
@@ -1773,3 +1804,8 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
 
     return -1;
 }
+
+bool used_memslots_is_exceeded(void)
+{
+    return used_memslots_exceeded;
+}
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index 8825bd278f..ed43a93692 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -124,6 +124,9 @@ typedef int (*vhost_get_device_id_op)(struct vhost_dev *dev, uint32_t *dev_id);
 
 typedef bool (*vhost_force_iommu_op)(struct vhost_dev *dev);
 
+typedef void (*vhost_set_used_memslots_op)(struct vhost_dev *dev);
+typedef unsigned int (*vhost_get_used_memslots_op)(void);
+
 typedef struct VhostOps {
     VhostBackendType backend_type;
     vhost_backend_init vhost_backend_init;
@@ -168,6 +171,8 @@ typedef struct VhostOps {
     vhost_vq_get_addr_op  vhost_vq_get_addr;
     vhost_get_device_id_op vhost_get_device_id;
     vhost_force_iommu_op vhost_force_iommu;
+    vhost_set_used_memslots_op vhost_set_used_memslots;
+    vhost_get_used_memslots_op vhost_get_used_memslots;
 } VhostOps;
 
 extern const VhostOps user_ops;
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 767a95ec0b..bf7cec445f 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -144,4 +144,5 @@ int vhost_dev_set_inflight(struct vhost_dev *dev,
                            struct vhost_inflight *inflight);
 int vhost_dev_get_inflight(struct vhost_dev *dev, uint16_t queue_size,
                            struct vhost_inflight *inflight);
+bool used_memslots_is_exceeded(void);
 #endif
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 17532daaf3..2f0216b518 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -20,6 +20,7 @@
 #include "qemu/error-report.h"
 #include "qemu/option.h"
 #include "trace.h"
+#include "include/hw/virtio/vhost.h"
 
 typedef struct NetVhostUserState {
     NetClientState nc;
@@ -347,6 +348,12 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
         qemu_chr_fe_set_handlers(&s->chr, NULL, NULL,
                                  net_vhost_user_event, NULL, nc0->name, NULL,
                                  true);
+
+        if (used_memslots_is_exceeded()) {
+            error_report("used memslots exceeded the backend limit, quit "
+                            "loop");
+            goto err;
+        }
     } while (!s->started);
 
     assert(s->vhost_net);
-- 
2.27.0.dirty



^ permalink raw reply related	[flat|nested] 23+ messages in thread
* [PATCH] vhost-user: add separate memslot counter for vhost-user
@ 2020-08-07  9:47 Jiajun Chen
  2020-08-07  9:55 ` no-reply
  0 siblings, 1 reply; 23+ messages in thread
From: Jiajun Chen @ 2020-08-07  9:47 UTC (permalink / raw)
  To: mst, jasowang; +Cc: qemu-devel, xiexiangyou, zhang.zhanghailiang

Used_memslots is equal to dev->mem->nregions now, it is true for
vhost kernel, but not for vhost user, which uses the memory regions
that have file descriptor. In fact, not all of the memory regions
have file descriptor.
It is usefully in some scenarios, e.g. used_memslots is 8, and only
5 memory slots can be used by vhost user, it is failed to hot plug
a new memory RAM because vhost_has_free_slot just returned false,
but we can hot plug it safely in fact.

Signed-off-by: Jiajun Chen <chenjiajun8@huawei.com>
Signed-off-by: Jianjay Zhou <jianjay.zhou@huawei.com>
---
 hw/virtio/vhost-backend.c         | 14 ++++++++
 hw/virtio/vhost-user.c            | 28 ++++++++++++++++
 hw/virtio/vhost.c                 | 54 +++++++++++++++++++++++++------
 include/hw/virtio/vhost-backend.h |  5 +++
 include/hw/virtio/vhost.h         |  1 +
 net/vhost-user.c                  |  7 ++++
 6 files changed, 100 insertions(+), 9 deletions(-)

diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
index 782b1d67d9..35eec7e166 100644
--- a/hw/virtio/vhost-backend.c
+++ b/hw/virtio/vhost-backend.c
@@ -20,6 +20,8 @@
 #include <linux/vhost.h>
 #include <sys/ioctl.h>
 
+static unsigned int vhost_kernel_used_memslots;
+
 static int vhost_kernel_call(struct vhost_dev *dev, unsigned long int request,
                              void *arg)
 {
@@ -238,6 +240,16 @@ static void vhost_kernel_set_iotlb_callback(struct vhost_dev *dev,
         qemu_set_fd_handler((uintptr_t)dev->opaque, NULL, NULL, NULL);
 }
 
+static void vhost_kernel_set_used_memslots(struct vhost_dev *dev)
+{
+    vhost_kernel_used_memslots = dev->mem->nregions;
+}
+
+static unsigned int vhost_kernel_get_used_memslots(void)
+{
+    return vhost_kernel_used_memslots;
+}
+
 static const VhostOps kernel_ops = {
         .backend_type = VHOST_BACKEND_TYPE_KERNEL,
         .vhost_backend_init = vhost_kernel_init,
@@ -269,6 +281,8 @@ static const VhostOps kernel_ops = {
 #endif /* CONFIG_VHOST_VSOCK */
         .vhost_set_iotlb_callback = vhost_kernel_set_iotlb_callback,
         .vhost_send_device_iotlb_msg = vhost_kernel_send_device_iotlb_msg,
+        .vhost_set_used_memslots = vhost_kernel_set_used_memslots,
+        .vhost_get_used_memslots = vhost_kernel_get_used_memslots,
 };
 #endif
 
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 31231218dc..04d20fc3ee 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -232,6 +232,7 @@ static VhostUserMsg m __attribute__ ((unused));
 
 /* The version of the protocol we support */
 #define VHOST_USER_VERSION    (0x1)
+static unsigned int vhost_user_used_memslots;
 
 struct vhost_user {
     struct vhost_dev *dev;
@@ -2354,6 +2355,31 @@ void vhost_user_cleanup(VhostUserState *user)
     user->chr = NULL;
 }
 
+static void vhost_user_set_used_memslots(struct vhost_dev *dev)
+{
+    unsigned int counter = 0;
+    int i;
+
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        ram_addr_t offset;
+        MemoryRegion *mr;
+
+        assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
+        mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
+                                    &offset);
+        if (mr && memory_region_get_fd(mr) > 0) {
+            counter++;
+        }
+    }
+    vhost_user_used_memslots = counter;
+}
+
+static unsigned int vhost_user_get_used_memslots(void)
+{
+    return vhost_user_used_memslots;
+}
+
 const VhostOps user_ops = {
         .backend_type = VHOST_BACKEND_TYPE_USER,
         .vhost_backend_init = vhost_user_backend_init,
@@ -2387,4 +2413,6 @@ const VhostOps user_ops = {
         .vhost_backend_mem_section_filter = vhost_user_mem_section_filter,
         .vhost_get_inflight_fd = vhost_user_get_inflight_fd,
         .vhost_set_inflight_fd = vhost_user_set_inflight_fd,
+        .vhost_set_used_memslots = vhost_user_set_used_memslots,
+        .vhost_get_used_memslots = vhost_user_get_used_memslots,
 };
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 1a1384e7a6..7f36d7af25 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -45,20 +45,22 @@
 static struct vhost_log *vhost_log;
 static struct vhost_log *vhost_log_shm;
 
-static unsigned int used_memslots;
 static QLIST_HEAD(, vhost_dev) vhost_devices =
     QLIST_HEAD_INITIALIZER(vhost_devices);
 
+bool used_memslots_exceeded;
+
 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);
+        if (hdev->vhost_ops->vhost_get_used_memslots() >=
+            hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+            return false;
+        }
     }
-    return slots_limit > used_memslots;
+    return true;
 }
 
 static void vhost_dev_sync_region(struct vhost_dev *dev,
@@ -502,7 +504,6 @@ static void vhost_commit(MemoryListener *listener)
                        dev->n_mem_sections * sizeof dev->mem->regions[0];
     dev->mem = g_realloc(dev->mem, regions_size);
     dev->mem->nregions = dev->n_mem_sections;
-    used_memslots = dev->mem->nregions;
     for (i = 0; i < dev->n_mem_sections; i++) {
         struct vhost_memory_region *cur_vmr = dev->mem->regions + i;
         struct MemoryRegionSection *mrs = dev->mem_sections + i;
@@ -678,6 +679,7 @@ static void vhost_region_add_section(struct vhost_dev *dev,
         dev->tmp_sections[dev->n_tmp_sections - 1].fv = NULL;
         memory_region_ref(section->mr);
     }
+    dev->vhost_ops->vhost_set_used_memslots(dev);
 }
 
 /* Used for both add and nop callbacks */
@@ -693,6 +695,17 @@ static void vhost_region_addnop(MemoryListener *listener,
     vhost_region_add_section(dev, section);
 }
 
+static void vhost_region_del(MemoryListener *listener,
+                             MemoryRegionSection *section)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         memory_listener);
+    if (!vhost_section(dev, section)) {
+        return;
+    }
+    dev->vhost_ops->vhost_set_used_memslots(dev);
+}
+
 static void vhost_iommu_unmap_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
 {
     struct vhost_iommu *iommu = container_of(n, struct vhost_iommu, n);
@@ -1248,6 +1261,19 @@ static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
     event_notifier_cleanup(&vq->masked_notifier);
 }
 
+static bool vhost_dev_used_memslots_is_exceeded(struct vhost_dev *hdev)
+{
+    if (hdev->vhost_ops->vhost_get_used_memslots() >
+        hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+        error_report("vhost backend memory slots limit is less"
+                " than current number of present memory slots");
+        used_memslots_exceeded = true;
+        return true;
+    }
+    used_memslots_exceeded = false;
+    return false;
+}
+
 int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
                    VhostBackendType backend_type, uint32_t busyloop_timeout)
 {
@@ -1300,6 +1326,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     hdev->memory_listener = (MemoryListener) {
         .begin = vhost_begin,
         .commit = vhost_commit,
+        .region_del = vhost_region_del,
         .region_add = vhost_region_addnop,
         .region_nop = vhost_region_addnop,
         .log_start = vhost_log_start,
@@ -1346,9 +1373,13 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     memory_listener_register(&hdev->memory_listener, &address_space_memory);
     QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
 
-    if (used_memslots > hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
-        error_report("vhost backend memory slots limit is less"
-                " than current number of present memory slots");
+    /*
+     * If we started a VM without any vhost device,
+     * vhost_dev_used_memslots_is_exceeded will always return false for the
+     * first time vhost device hot-plug(vhost_get_used_memslots is always 0),
+     * so it needs to double check here
+     */
+    if (vhost_dev_used_memslots_is_exceeded(hdev)) {
         r = -1;
         if (busyloop_timeout) {
             goto fail_busyloop;
@@ -1773,3 +1804,8 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
 
     return -1;
 }
+
+bool used_memslots_is_exceeded(void)
+{
+    return used_memslots_exceeded;
+}
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index 8825bd278f..ed43a93692 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -124,6 +124,9 @@ typedef int (*vhost_get_device_id_op)(struct vhost_dev *dev, uint32_t *dev_id);
 
 typedef bool (*vhost_force_iommu_op)(struct vhost_dev *dev);
 
+typedef void (*vhost_set_used_memslots_op)(struct vhost_dev *dev);
+typedef unsigned int (*vhost_get_used_memslots_op)(void);
+
 typedef struct VhostOps {
     VhostBackendType backend_type;
     vhost_backend_init vhost_backend_init;
@@ -168,6 +171,8 @@ typedef struct VhostOps {
     vhost_vq_get_addr_op  vhost_vq_get_addr;
     vhost_get_device_id_op vhost_get_device_id;
     vhost_force_iommu_op vhost_force_iommu;
+    vhost_set_used_memslots_op vhost_set_used_memslots;
+    vhost_get_used_memslots_op vhost_get_used_memslots;
 } VhostOps;
 
 extern const VhostOps user_ops;
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 767a95ec0b..bf7cec445f 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -144,4 +144,5 @@ int vhost_dev_set_inflight(struct vhost_dev *dev,
                            struct vhost_inflight *inflight);
 int vhost_dev_get_inflight(struct vhost_dev *dev, uint16_t queue_size,
                            struct vhost_inflight *inflight);
+bool used_memslots_is_exceeded(void);
 #endif
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 17532daaf3..2f0216b518 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -20,6 +20,7 @@
 #include "qemu/error-report.h"
 #include "qemu/option.h"
 #include "trace.h"
+#include "include/hw/virtio/vhost.h"
 
 typedef struct NetVhostUserState {
     NetClientState nc;
@@ -347,6 +348,12 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
         qemu_chr_fe_set_handlers(&s->chr, NULL, NULL,
                                  net_vhost_user_event, NULL, nc0->name, NULL,
                                  true);
+
+        if (used_memslots_is_exceeded()) {
+            error_report("used memslots exceeded the backend limit, quit "
+                            "loop");
+            goto err;
+        }
     } while (!s->started);
 
     assert(s->vhost_net);
-- 
2.27.0.dirty



^ permalink raw reply related	[flat|nested] 23+ messages in thread
* [PATCH] vhost-user: add separate memslot counter for vhost-user
@ 2020-08-07  8:19 Jiajun Chen
  2020-08-07  8:25 ` no-reply
  0 siblings, 1 reply; 23+ messages in thread
From: Jiajun Chen @ 2020-08-07  8:19 UTC (permalink / raw)
  To: mst, jasowang; +Cc: qemu-devel, xiexiangyou, zhang.zhanghailiang

Used_memslots is equal to dev->mem->nregions now, it is true for
vhost kernel, but not for vhost user, which uses the memory regions
that have file descriptor. In fact, not all of the memory regions
have file descriptor.
It is usefully in some scenarios, e.g. used_memslots is 8, and only
5 memory slots can be used by vhost user, it is failed to hot plug
a new memory RAM because vhost_has_free_slot just returned false,
but we can hot plug it safely in fact.

Signed-off-by: Jiajun Chen <chenjiajun8@huawei.com>
Signed-off-by: Jianjay Zhou <jianjay.zhou@huawei.com>
---
 hw/virtio/vhost-backend.c         | 14 ++++++++
 hw/virtio/vhost-user.c            | 28 ++++++++++++++++
 hw/virtio/vhost.c                 | 54 +++++++++++++++++++++++++------
 include/hw/virtio/vhost-backend.h |  5 +++
 include/hw/virtio/vhost.h         |  1 +
 net/vhost-user.c                  |  7 ++++
 6 files changed, 100 insertions(+), 9 deletions(-)

diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
index 782b1d67d9..35eec7e166 100644
--- a/hw/virtio/vhost-backend.c
+++ b/hw/virtio/vhost-backend.c
@@ -20,6 +20,8 @@
 #include <linux/vhost.h>
 #include <sys/ioctl.h>
 
+static unsigned int vhost_kernel_used_memslots;
+
 static int vhost_kernel_call(struct vhost_dev *dev, unsigned long int request,
                              void *arg)
 {
@@ -238,6 +240,16 @@ static void vhost_kernel_set_iotlb_callback(struct vhost_dev *dev,
         qemu_set_fd_handler((uintptr_t)dev->opaque, NULL, NULL, NULL);
 }
 
+static void vhost_kernel_set_used_memslots(struct vhost_dev *dev)
+{
+    vhost_kernel_used_memslots = dev->mem->nregions;
+}
+
+static unsigned int vhost_kernel_get_used_memslots(void)
+{
+    return vhost_kernel_used_memslots;
+}
+
 static const VhostOps kernel_ops = {
         .backend_type = VHOST_BACKEND_TYPE_KERNEL,
         .vhost_backend_init = vhost_kernel_init,
@@ -269,6 +281,8 @@ static const VhostOps kernel_ops = {
 #endif /* CONFIG_VHOST_VSOCK */
         .vhost_set_iotlb_callback = vhost_kernel_set_iotlb_callback,
         .vhost_send_device_iotlb_msg = vhost_kernel_send_device_iotlb_msg,
+        .vhost_set_used_memslots = vhost_kernel_set_used_memslots,
+        .vhost_get_used_memslots = vhost_kernel_get_used_memslots,
 };
 #endif
 
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 31231218dc..04d20fc3ee 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -232,6 +232,7 @@ static VhostUserMsg m __attribute__ ((unused));
 
 /* The version of the protocol we support */
 #define VHOST_USER_VERSION    (0x1)
+static unsigned int vhost_user_used_memslots;
 
 struct vhost_user {
     struct vhost_dev *dev;
@@ -2354,6 +2355,31 @@ void vhost_user_cleanup(VhostUserState *user)
     user->chr = NULL;
 }
 
+static void vhost_user_set_used_memslots(struct vhost_dev *dev)
+{
+    unsigned int counter = 0;
+    int i;
+
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        ram_addr_t offset;
+        MemoryRegion *mr;
+
+        assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
+        mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
+                                    &offset);
+        if (mr && memory_region_get_fd(mr) > 0) {
+            counter++;
+        }
+    }
+    vhost_user_used_memslots = counter;
+}
+
+static unsigned int vhost_user_get_used_memslots(void)
+{
+    return vhost_user_used_memslots;
+}
+
 const VhostOps user_ops = {
         .backend_type = VHOST_BACKEND_TYPE_USER,
         .vhost_backend_init = vhost_user_backend_init,
@@ -2387,4 +2413,6 @@ const VhostOps user_ops = {
         .vhost_backend_mem_section_filter = vhost_user_mem_section_filter,
         .vhost_get_inflight_fd = vhost_user_get_inflight_fd,
         .vhost_set_inflight_fd = vhost_user_set_inflight_fd,
+        .vhost_set_used_memslots = vhost_user_set_used_memslots,
+        .vhost_get_used_memslots = vhost_user_get_used_memslots,
 };
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 1a1384e7a6..7f36d7af25 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -45,20 +45,22 @@
 static struct vhost_log *vhost_log;
 static struct vhost_log *vhost_log_shm;
 
-static unsigned int used_memslots;
 static QLIST_HEAD(, vhost_dev) vhost_devices =
     QLIST_HEAD_INITIALIZER(vhost_devices);
 
+bool used_memslots_exceeded;
+
 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);
+        if (hdev->vhost_ops->vhost_get_used_memslots() >=
+            hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+            return false;
+        }
     }
-    return slots_limit > used_memslots;
+    return true;
 }
 
 static void vhost_dev_sync_region(struct vhost_dev *dev,
@@ -502,7 +504,6 @@ static void vhost_commit(MemoryListener *listener)
                        dev->n_mem_sections * sizeof dev->mem->regions[0];
     dev->mem = g_realloc(dev->mem, regions_size);
     dev->mem->nregions = dev->n_mem_sections;
-    used_memslots = dev->mem->nregions;
     for (i = 0; i < dev->n_mem_sections; i++) {
         struct vhost_memory_region *cur_vmr = dev->mem->regions + i;
         struct MemoryRegionSection *mrs = dev->mem_sections + i;
@@ -678,6 +679,7 @@ static void vhost_region_add_section(struct vhost_dev *dev,
         dev->tmp_sections[dev->n_tmp_sections - 1].fv = NULL;
         memory_region_ref(section->mr);
     }
+    dev->vhost_ops->vhost_set_used_memslots(dev);
 }
 
 /* Used for both add and nop callbacks */
@@ -693,6 +695,17 @@ static void vhost_region_addnop(MemoryListener *listener,
     vhost_region_add_section(dev, section);
 }
 
+static void vhost_region_del(MemoryListener *listener,
+                             MemoryRegionSection *section)
+{
+    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
+                                         memory_listener);
+    if (!vhost_section(dev, section)) {
+        return;
+    }
+    dev->vhost_ops->vhost_set_used_memslots(dev);
+}
+
 static void vhost_iommu_unmap_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
 {
     struct vhost_iommu *iommu = container_of(n, struct vhost_iommu, n);
@@ -1248,6 +1261,19 @@ static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
     event_notifier_cleanup(&vq->masked_notifier);
 }
 
+static bool vhost_dev_used_memslots_is_exceeded(struct vhost_dev *hdev)
+{
+    if (hdev->vhost_ops->vhost_get_used_memslots() >
+        hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
+        error_report("vhost backend memory slots limit is less"
+                " than current number of present memory slots");
+        used_memslots_exceeded = true;
+        return true;
+    }
+    used_memslots_exceeded = false;
+    return false;
+}
+
 int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
                    VhostBackendType backend_type, uint32_t busyloop_timeout)
 {
@@ -1300,6 +1326,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     hdev->memory_listener = (MemoryListener) {
         .begin = vhost_begin,
         .commit = vhost_commit,
+        .region_del = vhost_region_del,
         .region_add = vhost_region_addnop,
         .region_nop = vhost_region_addnop,
         .log_start = vhost_log_start,
@@ -1346,9 +1373,13 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     memory_listener_register(&hdev->memory_listener, &address_space_memory);
     QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
 
-    if (used_memslots > hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
-        error_report("vhost backend memory slots limit is less"
-                " than current number of present memory slots");
+    /*
+     * If we started a VM without any vhost device,
+     * vhost_dev_used_memslots_is_exceeded will always return false for the
+     * first time vhost device hot-plug(vhost_get_used_memslots is always 0),
+     * so it needs to double check here
+     */
+    if (vhost_dev_used_memslots_is_exceeded(hdev)) {
         r = -1;
         if (busyloop_timeout) {
             goto fail_busyloop;
@@ -1773,3 +1804,8 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
 
     return -1;
 }
+
+bool used_memslots_is_exceeded(void)
+{
+    return used_memslots_exceeded;
+}
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index 8825bd278f..ed43a93692 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -124,6 +124,9 @@ typedef int (*vhost_get_device_id_op)(struct vhost_dev *dev, uint32_t *dev_id);
 
 typedef bool (*vhost_force_iommu_op)(struct vhost_dev *dev);
 
+typedef void (*vhost_set_used_memslots_op)(struct vhost_dev *dev);
+typedef unsigned int (*vhost_get_used_memslots_op)(void);
+
 typedef struct VhostOps {
     VhostBackendType backend_type;
     vhost_backend_init vhost_backend_init;
@@ -168,6 +171,8 @@ typedef struct VhostOps {
     vhost_vq_get_addr_op  vhost_vq_get_addr;
     vhost_get_device_id_op vhost_get_device_id;
     vhost_force_iommu_op vhost_force_iommu;
+    vhost_set_used_memslots_op vhost_set_used_memslots;
+    vhost_get_used_memslots_op vhost_get_used_memslots;
 } VhostOps;
 
 extern const VhostOps user_ops;
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 767a95ec0b..bf7cec445f 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -144,4 +144,5 @@ int vhost_dev_set_inflight(struct vhost_dev *dev,
                            struct vhost_inflight *inflight);
 int vhost_dev_get_inflight(struct vhost_dev *dev, uint16_t queue_size,
                            struct vhost_inflight *inflight);
+bool used_memslots_is_exceeded(void);
 #endif
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 17532daaf3..2f0216b518 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -20,6 +20,7 @@
 #include "qemu/error-report.h"
 #include "qemu/option.h"
 #include "trace.h"
+#include "include/hw/virtio/vhost.h"
 
 typedef struct NetVhostUserState {
     NetClientState nc;
@@ -347,6 +348,12 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
         qemu_chr_fe_set_handlers(&s->chr, NULL, NULL,
                                  net_vhost_user_event, NULL, nc0->name, NULL,
                                  true);
+
+        if (used_memslots_is_exceeded()) {
+            error_report("used memslots exceeded the backend limit, quit "
+                            "loop");
+            goto err;
+        }
     } while (!s->started);
 
     assert(s->vhost_net);
-- 
2.27.0.dirty



^ permalink raw reply related	[flat|nested] 23+ messages in thread
end of thread, other threads:[~2020-10-30  8:40 UTC | newest]

Thread overview: 23+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-09-28 13:17 [PATCH] vhost-user: add separate memslot counter for vhost-user Jiajun Chen
2020-10-02  2:05 ` Raphael Norwitz
2020-10-12 11:12   ` chenjiajun
2020-10-14  1:22     ` Raphael Norwitz
2020-10-06  9:48 ` Igor Mammedov
2020-10-14  0:58   ` Raphael Norwitz
2020-10-14  7:08     ` Michael S. Tsirkin
2020-10-14 16:11       ` Raphael Norwitz
2020-10-14 16:26         ` Michael S. Tsirkin
2020-10-14 17:21           ` Raphael Norwitz
2020-10-14 17:54             ` Michael S. Tsirkin
2020-10-21 14:34         ` Igor Mammedov
2020-10-30  8:39 ` Michael S. Tsirkin
  -- strict thread matches above, loose matches on Subject: below --
2020-09-08  6:11 Jiajun Chen
2020-09-08  8:37 ` Michael S. Tsirkin
2020-09-15  1:27 ` Raphael Norwitz
2020-08-11  1:43 Jiajun Chen
2020-08-27 12:11 ` Michael S. Tsirkin
2020-09-02  5:02 ` Raphael Norwitz
2020-08-07  9:47 Jiajun Chen
2020-08-07  9:55 ` no-reply
2020-08-07  8:19 Jiajun Chen
2020-08-07  8:25 ` no-reply

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