Hello,
occasionally we encounter a null pointer access in VMEmt.cpp. We added
an assertion like
+++ src/VBox/VMM/VMMR3/VMEmt.cpp
@@ -156,6 +156,10 @@
PVM pVM = pUVM->pVM;
PVMCPU pVCpu = pUVCpu->pVCpu;
enmBefore = pVM->enmVMState;
+
+ Assert(pVM);
+ Assert(pVCpu);
+
if (pUVM->vm.s.fTerminateEMT)
{
rc = VINF_EM_TERMINATE;
The second assertion triggers from time to time during early bootstrap
of a VM and using multiple vCPUs.
After some debugging in turned out, that the assignment of the pUVM->pVM
pointer in VM.cpp is done to early, so that the actual pUVM->aCpus[] are
not yet initialized.
Following kind of quirk avoid the issue for us:
+++ src/VBox/VMM/VMMR3/VM.cpp
@@ -605,7 +605,7 @@
rc = SUPR3CallVMMR0Ex(NIL_RTR0PTR, NIL_VMCPUID,
VMMR0_DO_GVMM_CREATE_VM, 0, &CreateVMReq.Hdr);
if (RT_SUCCESS(rc))
{
- PVM pVM = pUVM->pVM = CreateVMReq.pVMR3;
+ PVM pVM = CreateVMReq.pVMR3;
AssertRelease(VALID_PTR(pVM));
AssertRelease(pVM->pVMR0 == CreateVMReq.pVMR0);
AssertRelease(pVM->pSession == pUVM->vm.s.pSession);
@@ -635,6 +635,14 @@
pUVM->aCpus[i].pVM = pVM;
}
+ /*
+ * vmR3EmulationThreadWithId checks (from within another
thread) for
+ * !pUVM->pVM. If not null the function also expects
+ * pUVM->aCpus[i].pVCpu to be not null. So, make the assignment
after
+ * pUVM->aCpus[i] are actually initialized.
+ */
+ ASMCompilerBarrier();
+ pUVM->pVM = pVM;
/*
* Init the configuration.
We encountered/have seen the issue occasionally in 5.1.10 - 5.1.16.
Cheers,
--
Alexander Boettcher
Genode Labs
http://www.genode-labs.com - http://www.genode.org
Genode Labs GmbH - Amtsgericht Dresden - HRB 28424 - Sitz Dresden
Geschäftsführer: Dr.-Ing. Norman Feske, Christian Helmuth
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