On 07/07/2011 08:07 PM, Glauber Costa wrote:
+static void record_steal_time(struct kvm_vcpu *vcpu)
+{
+ u64 delta;
+
+ if (!(vcpu->arch.st.msr_val& KVM_MSR_ENABLED))
+ return;
+
+ if (unlikely(kvm_read_guest_cached(vcpu->kvm,&vcpu->arch.st.stime,
+ &vcpu->arch.st.steal, sizeof(struct kvm_steal_time))))
+ return;
The guest memory page is not pinned, sleeping via
__copy_from_user/to_user is not allowed in vcpu_load context. Either pin
it or use atomic acessors.
I do recognize the problem.
Avi, what's your take here?
The easiest solution is to set a KVM_REQ bit in atomic context, and move
the sleepy code to vcpu_enter_guest().
+ case MSR_KVM_STEAL_TIME:
+ vcpu->arch.st.msr_val = data;
+
+ if (!(data& KVM_MSR_ENABLED)) {
+ break;
+ }
On failure below this point, msr_val should be cleared of
KVM_MSR_ENABLED?
No, msr_val has to hold whatever the guest wrote into it.
We should probably use an independent variable here to indicate that
we failed to activate it.
If we fail, we return a #GP to the guest (and don't write any value into
the msr).
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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