[PATCH 33/45] KVM: VMX: Handle mmio emulation when guest state is invalid

Avi Kivity
2008-12-08T11:45:55Z

From: Guillaume Thouvenin <guillaume.thouvenin@ext.bull.net>

If emulate_invalid_guest_state is enabled, the emulator is called
when guest state is invalid. Until now, we reported an mmio failure
when emulate_instruction() returned EMULATE_DO_MMIO. This patch adds
the case where emulate_instruction() failed and an MMIO emulation
is needed.

Signed-off-by: Guillaume Thouvenin <guillaume.thouvenin@ext.bull.net>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/x86/kvm/vmx.c | 27 +++++++++++++++------------
1 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 816d231..427dbc1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3052,16 +3052,12 @@ static void handle_invalid_guest_state(struct kvm_vcpu *vcpu,
while (!guest_state_valid(vcpu)) {
err = emulate_instruction(vcpu, kvm_run, 0, 0, 0);

- switch (err) {
- case EMULATE_DONE:
- break;
- case EMULATE_DO_MMIO:
- kvm_report_emulation_failure(vcpu, "mmio");
- /* TODO: Handle MMIO */
- return;
- default:
- kvm_report_emulation_failure(vcpu, "emulation failure");
- return;
+ if (err == EMULATE_DO_MMIO)
+ break;
+
+ if (err != EMULATE_DONE) {
+ kvm_report_emulation_failure(vcpu, "emulation failure");
+ return;
}

if (signal_pending(current))
@@ -3073,8 +3069,10 @@ static void handle_invalid_guest_state(struct kvm_vcpu *vcpu,
local_irq_disable();
preempt_disable();

- /* Guest state should be valid now, no more emulation should be needed */
- vmx->emulation_required = 0;
+ /* Guest state should be valid now except if we need to
+ * emulate an MMIO */
+ if (guest_state_valid(vcpu))
+ vmx->emulation_required = 0;
}

/*
@@ -3121,6 +3119,11 @@ static int kvm_handle_exit(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
KVMTRACE_3D(VMEXIT, vcpu, exit_reason, (u32)kvm_rip_read(vcpu),
(u32)((u64)kvm_rip_read(vcpu) >> 32), entryexit);

+ /* If we need to emulate an MMIO from handle_invalid_guest_state
+ * we just return 0 */
+ if (vmx->emulation_required && emulate_invalid_guest_state)
+ return 0;
+
/* Access CR3 don't cause VMExit in paging mode, so we need
* to sync with guest real CR3. */
if (vm_need_ept() && is_paging(vcpu)) {
--
1.6.0.3