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KVM: x86 emulator: restart string instruction without going back to a guest.

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Currently when string instruction is only partially complete we go back
to a guest mode, guest tries to reexecute instruction and exits again
and at this point emulation continues. Avoid all of this by restarting
instruction without going back to a guest mode, but return to a guest
mode each 1024 iterations to allow interrupt injection. Pending
exception causes immediate guest entry too.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Gleb Natapov
2010-03-18 15:20:26 +02:00
committed by Avi Kivity
parent cb404fe089
commit 5cd21917da
3 changed files with 42 additions and 12 deletions
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19
arch/x86/kvm/x86.c
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@@ -3755,6 +3755,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
return EMULATE_DONE;
}
restart:
r = x86_emulate_insn(&vcpu->arch.emulate_ctxt, &emulate_ops);
shadow_mask = vcpu->arch.emulate_ctxt.interruptibility;
@@ -3777,7 +3778,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
if (r) {
if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
return EMULATE_DONE;
goto done;
if (!vcpu->mmio_needed) {
kvm_report_emulation_failure(vcpu, "mmio");
return EMULATE_FAIL;
@@ -3792,6 +3793,13 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
return EMULATE_DO_MMIO;
}
done:
if (vcpu->arch.exception.pending)
vcpu->arch.emulate_ctxt.restart = false;
if (vcpu->arch.emulate_ctxt.restart)
goto restart;
return EMULATE_DONE;
}
EXPORT_SYMBOL_GPL(emulate_instruction);
@@ -4560,6 +4568,15 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
goto out;
}
}
if (vcpu->arch.emulate_ctxt.restart) {
vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
r = emulate_instruction(vcpu, 0, 0, EMULTYPE_NO_DECODE);
srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
if (r == EMULATE_DO_MMIO) {
r = 0;
goto out;
}
}
if (kvm_run->exit_reason == KVM_EXIT_HYPERCALL)
kvm_register_write(vcpu, VCPU_REGS_RAX,
kvm_run->hypercall.ret);