Merge tag 'pull-hv-balloon-20240308' of https://github.com/maciejsszmigiero/qemu into staging

Hyper-V Dynamic Memory and VMBus misc small patches

This pull request contains two small patches to hv-balloon:
the first one replacing alloca() usage with g_malloc0() + g_autofree
and the second one adding additional declaration of a protocol message
struct with an optional field explicitly defined to avoid a Coverity
warning.

Also included is a VMBus patch to print a warning when it is enabled
without the recommended set of Hyper-V features (enlightenments) since
some Windows versions crash at boot in this case.

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# gpg: Signature made Fri 08 Mar 2024 16:50:43 GMT
# gpg:                using RSA key E2776AABA08E26FF5A1B4A0952B1D6E951D0CE07
# gpg: Good signature from "Maciej S. Szmigiero <mail@maciej.szmigiero.name>" [unknown]
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* tag 'pull-hv-balloon-20240308' of https://github.com/maciejsszmigiero/qemu:
  vmbus: Print a warning when enabled without the recommended set of features
  hv-balloon: define dm_hot_add_with_region to avoid Coverity warning
  hv-balloon: avoid alloca() usage

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

9 files changed, 56 insertions, 11 deletions

diff --git a/hw/hyperv/hv-balloon.c b/hw/hyperv/hv-balloon.c
index ade2833..3a9ef07 100644
--- a/hw/hyperv/hv-balloon.c
+++ b/hw/hyperv/hv-balloon.c
@@ -366,7 +366,7 @@ static void hv_balloon_unballoon_posting(HvBalloon *balloon, StateDesc *stdesc)
     PageRangeTree dtree;
     uint64_t *dctr;
     bool our_range;
-    struct dm_unballoon_request *ur;
+    g_autofree struct dm_unballoon_request *ur = NULL;
     size_t ur_size = sizeof(*ur) + sizeof(ur->range_array[0]);
     PageRange range;
     bool bret;
@@ -388,8 +388,7 @@ static void hv_balloon_unballoon_posting(HvBalloon *balloon, StateDesc *stdesc)
     assert(dtree.t);
     assert(dctr);
 
-    ur = alloca(ur_size);
-    memset(ur, 0, ur_size);
+    ur = g_malloc0(ur_size);
     ur->hdr.type = DM_UNBALLOON_REQUEST;
     ur->hdr.size = ur_size;
     ur->hdr.trans_id = balloon->trans_id;
@@ -514,8 +513,8 @@ ret_idle:
 static void hv_balloon_hot_add_rb_wait(HvBalloon *balloon, StateDesc *stdesc)
 {
     VMBusChannel *chan = hv_balloon_get_channel(balloon);
-    struct dm_hot_add *ha;
-    size_t ha_size = sizeof(*ha) + sizeof(ha->range);
+    struct dm_hot_add_with_region *ha;
+    size_t ha_size = sizeof(*ha);
 
     assert(balloon->state == S_HOT_ADD_RB_WAIT);
 
@@ -531,8 +530,8 @@ static void hv_balloon_hot_add_posting(HvBalloon *balloon, StateDesc *stdesc)
     PageRange *hot_add_range = &balloon->hot_add_range;
     uint64_t *current_count = &balloon->ha_current_count;
     VMBusChannel *chan = hv_balloon_get_channel(balloon);
-    struct dm_hot_add *ha;
-    size_t ha_size = sizeof(*ha) + sizeof(ha->range);
+    g_autofree struct dm_hot_add_with_region *ha = NULL;
+    size_t ha_size = sizeof(*ha);
     union dm_mem_page_range *ha_region;
     uint64_t align, chunk_max_size;
     ssize_t ret;
@@ -560,9 +559,8 @@ static void hv_balloon_hot_add_posting(HvBalloon *balloon, StateDesc *stdesc)
      */
     *current_count = MIN(hot_add_range->count, chunk_max_size);
 
-    ha = alloca(ha_size);
-    ha_region = &(&ha->range)[1];
-    memset(ha, 0, ha_size);
+    ha = g_malloc0(ha_size);
+    ha_region = &ha->region;
     ha->hdr.type = DM_MEM_HOT_ADD_REQUEST;
     ha->hdr.size = ha_size;
     ha->hdr.trans_id = balloon->trans_id;
diff --git a/hw/hyperv/hyperv.c b/hw/hyperv/hyperv.c
index 6c4a18d..3ea54ba 100644
--- a/hw/hyperv/hyperv.c
+++ b/hw/hyperv/hyperv.c
@@ -951,3 +951,15 @@ uint64_t hyperv_syndbg_query_options(void)
 
     return msg.u.query_options.options;
 }
+
+static bool vmbus_recommended_features_enabled;
+
+bool hyperv_are_vmbus_recommended_features_enabled(void)
+{
+    return vmbus_recommended_features_enabled;
+}
+
+void hyperv_set_vmbus_recommended_features_enabled(void)
+{
+    vmbus_recommended_features_enabled = true;
+}
diff --git a/hw/hyperv/vmbus.c b/hw/hyperv/vmbus.c
index 380239a..f33afee 100644
--- a/hw/hyperv/vmbus.c
+++ b/hw/hyperv/vmbus.c
@@ -2631,6 +2631,12 @@ static void vmbus_bridge_realize(DeviceState *dev, Error **errp)
         return;
     }
 
+    if (!hyperv_are_vmbus_recommended_features_enabled()) {
+        warn_report("VMBus enabled without the recommended set of Hyper-V features: "
+                    "hv-stimer, hv-vapic and hv-runtime. "
+                    "Some Windows versions might not boot or enable the VMBus device");
+    }
+
     bridge->bus = VMBUS(qbus_new(TYPE_VMBUS, dev, "vmbus"));
 }
 
diff --git a/include/hw/hyperv/dynmem-proto.h b/include/hw/hyperv/dynmem-proto.h
index a657786..68b8b60 100644
--- a/include/hw/hyperv/dynmem-proto.h
+++ b/include/hw/hyperv/dynmem-proto.h
@@ -328,7 +328,8 @@ struct dm_unballoon_response {
 /*
  * Hot add request message. Message sent from the host to the guest.
  *
- * mem_range: Memory range to hot add.
+ * range: Memory range to hot add.
+ * region: Explicit hot add memory region for guest to use. Optional.
  *
  */
 
@@ -337,6 +338,12 @@ struct dm_hot_add {
     union dm_mem_page_range range;
 } QEMU_PACKED;
 
+struct dm_hot_add_with_region {
+    struct dm_header hdr;
+    union dm_mem_page_range range;
+    union dm_mem_page_range region;
+} QEMU_PACKED;
+
 /*
  * Hot add response message.
  * This message is sent by the guest to report the status of a hot add request.
diff --git a/include/hw/hyperv/hyperv.h b/include/hw/hyperv/hyperv.h
index 015c352..d717b4e 100644
--- a/include/hw/hyperv/hyperv.h
+++ b/include/hw/hyperv/hyperv.h
@@ -139,4 +139,8 @@ typedef struct HvSynDbgMsg {
 } HvSynDbgMsg;
 typedef uint16_t (*HvSynDbgHandler)(void *context, HvSynDbgMsg *msg);
 void hyperv_set_syndbg_handler(HvSynDbgHandler handler, void *context);
+
+bool hyperv_are_vmbus_recommended_features_enabled(void);
+void hyperv_set_vmbus_recommended_features_enabled(void);
+
 #endif
diff --git a/target/i386/kvm/hyperv-stub.c b/target/i386/kvm/hyperv-stub.c
index 778ed78..3263dcf 100644
--- a/target/i386/kvm/hyperv-stub.c
+++ b/target/i386/kvm/hyperv-stub.c
@@ -52,3 +52,7 @@ void hyperv_x86_synic_reset(X86CPU *cpu)
 void hyperv_x86_synic_update(X86CPU *cpu)
 {
 }
+
+void hyperv_x86_set_vmbus_recommended_features_enabled(void)
+{
+}
diff --git a/target/i386/kvm/hyperv.c b/target/i386/kvm/hyperv.c
index 6825c89..f2a3fe6 100644
--- a/target/i386/kvm/hyperv.c
+++ b/target/i386/kvm/hyperv.c
@@ -149,3 +149,8 @@ int kvm_hv_handle_exit(X86CPU *cpu, struct kvm_hyperv_exit *exit)
         return -1;
     }
 }
+
+void hyperv_x86_set_vmbus_recommended_features_enabled(void)
+{
+    hyperv_set_vmbus_recommended_features_enabled();
+}
diff --git a/target/i386/kvm/hyperv.h b/target/i386/kvm/hyperv.h
index 6754329..e3982c8 100644
--- a/target/i386/kvm/hyperv.h
+++ b/target/i386/kvm/hyperv.h
@@ -26,4 +26,6 @@ int hyperv_x86_synic_add(X86CPU *cpu);
 void hyperv_x86_synic_reset(X86CPU *cpu);
 void hyperv_x86_synic_update(X86CPU *cpu);
 
+void hyperv_x86_set_vmbus_recommended_features_enabled(void);
+
 #endif
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 42970ab..e68cbe9 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -1650,6 +1650,13 @@ static int hyperv_init_vcpu(X86CPU *cpu)
         }
     }
 
+    /* Skip SynIC and VP_INDEX since they are hard deps already */
+    if (hyperv_feat_enabled(cpu, HYPERV_FEAT_STIMER) &&
+        hyperv_feat_enabled(cpu, HYPERV_FEAT_VAPIC) &&
+        hyperv_feat_enabled(cpu, HYPERV_FEAT_RUNTIME)) {
+        hyperv_x86_set_vmbus_recommended_features_enabled();
+    }
+
     return 0;
 }