Re: [PATCH 5/6] KVM: x86: Preserve injected TF across emulation

Jan Kiszka
2010-02-23T10:13:32Z

Gleb Natapov wrote:
> On Mon, Feb 22, 2010 at 06:51:22PM +0100, Jan Kiszka wrote:
>> Call directly into the vendor services for getting/setting rflags in
>> emulate_instruction to ensure injected TF survives the emulation.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>> arch/x86/kvm/x86.c | 4 ++--
>> 1 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index e2e03a4..19e8b28 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -3468,7 +3468,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
>> kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
>>
>> vcpu->arch.emulate_ctxt.vcpu = vcpu;
>> - vcpu->arch.emulate_ctxt.eflags = kvm_get_rflags(vcpu);
>> + vcpu->arch.emulate_ctxt.eflags = kvm_x86_ops->get_rflags(vcpu);
> So now emulator runs with injected TF? Hmm, then may be emulator should
> inject DB when appropriate and caller of emulate_instruction() should
> emulate DB intercept if external debugging is going on?

That is what patch 6 aims at, both for external as well as
guest-internal debugging.

>
>> vcpu->arch.emulate_ctxt.mode =
>> (!is_protmode(vcpu)) ? X86EMUL_MODE_REAL :
>> (vcpu->arch.emulate_ctxt.eflags & X86_EFLAGS_VM)
>> @@ -3547,7 +3547,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
>> return EMULATE_DO_MMIO;
>> }
>>
>> - kvm_set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);
>> + kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);
>>
>> if (vcpu->mmio_is_write) {
>> vcpu->mmio_needed = 0;
>> --
>> 1.6.0.2

Jan

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