On 2013-03-14 11:15, Jan Kiszka wrote:
>>>
>>> - if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_SIPI_RECEIVED)) {
>>> - pr_debug("vcpu %d received sipi with vector # %x\n",
>>> - vcpu->vcpu_id, vcpu->arch.sipi_vector);
>>> - kvm_lapic_reset(vcpu);
>>> - kvm_vcpu_reset(vcpu);
>>> - vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
>>> - }
>>> -
>>> vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
>>> r = vapic_enter(vcpu);
>>
>> vmx_vcpu_reset overwrites vcpu->srcu_idx if ->vcpu_reset is called from
>> within srcu section.
>
> Indeed.
>
> Do you know what the look over vmx_set_cr0 actually protects?
Found it: It's not actually protecting anything. enter_rmode is called,
and that assumes that lock to be held. If enter_rmode faces an
uninitialized tss, it drops the lock before calling vmx_set_tss_addr.
Well, I wonder if that is a good place to fix the TSS issue. Why not
make that special case (lacking KVM_SET_TSS_ADDR before first KVM_RUN) a
static jump key and check for it on KVM_RUN?
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux
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