[PATCH 3/3] VMX: Enhance invalid guest state emulation

Mohammed Gamal
2009-08-28T14:49:26Z

- Change returned handle_invalid_guest_state() to return relevant exit codes
- Move triggering the emulation from vmx_vcpu_run() to vmx_handle_exit()
- Return to userspace instead of repeatedly trying to emulate
instructions that have already failed

Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
---
arch/x86/kvm/vmx.c | 24 ++++++++++++++----------
1 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 78101dd..e422470 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3318,10 +3318,11 @@ static int handle_nmi_window(struct kvm_vcpu *vcpu)
return 1;
}

-static void handle_invalid_guest_state(struct kvm_vcpu *vcpu)
+static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
enum emulation_result err = EMULATE_DONE;
+ int ret = 1;

local_irq_enable();
preempt_enable();
@@ -3329,11 +3330,16 @@ static void handle_invalid_guest_state(struct kvm_vcpu *vcpu)
while (!guest_state_valid(vcpu)) {
err = emulate_instruction(vcpu, 0, 0, 0);

- if (err == EMULATE_DO_MMIO)
+ if (err == EMULATE_DO_MMIO) {
+ ret = 0;
break;
+ }

if (err != EMULATE_DONE) {
kvm_report_emulation_failure(vcpu, "emulation failure");
+ vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+ vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
+ ret = 0;
break;
}

@@ -3347,6 +3353,7 @@ static void handle_invalid_guest_state(struct kvm_vcpu *vcpu)
local_irq_disable();

vmx->invalid_state_emulation_result = err;
+ return ret;
}

/*
@@ -3405,9 +3412,12 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
/* If we need to emulate an MMIO from handle_invalid_guest_state
* we just return 0 */
if (vmx->emulation_required && emulate_invalid_guest_state) {
- if (guest_state_valid(vcpu))
+ if (guest_state_valid(vcpu)) {
vmx->emulation_required = 0;
- return vmx->invalid_state_emulation_result != EMULATE_DO_MMIO;
+ return vmx->invalid_state_emulation_result != EMULATE_DO_MMIO;
+ } else {
+ return handle_invalid_guest_state(vcpu);
+ }
}

/* Access CR3 don't cause VMExit in paging mode, so we need
@@ -3603,12 +3613,6 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked))
vmx->entry_time = ktime_get();

- /* Handle invalid guest state instead of entering VMX */
- if (vmx->emulation_required && emulate_invalid_guest_state) {
- handle_invalid_guest_state(vcpu);
- return;
- }
-
if (test_bit(VCPU_REGS_RSP, (unsigned long *)&vcpu->arch.regs_dirty))
vmcs_writel(GUEST_RSP, vcpu->arch.regs[VCPU_REGS_RSP]);
if (test_bit(VCPU_REGS_RIP, (unsigned long *)&vcpu->arch.regs_dirty))
--
1.6.0.4