KVM: VMX: Modify mode switching and vmentry functions

This patch modifies mode switching and vmentry function in order to
drive invalid guest state emulation.

Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index eae1f2c64f9..9840f37925a 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1298,7 +1298,9 @@ static void fix_pmode_dataseg(int seg, struct kvm_save_segment *save)
 static void enter_pmode(struct kvm_vcpu *vcpu)
 {
         unsigned long flags;
+        struct vcpu_vmx *vmx = to_vmx(vcpu);
 
+        vmx->emulation_required = 1;
         vcpu->arch.rmode.active = 0;
 
         vmcs_writel(GUEST_TR_BASE, vcpu->arch.rmode.tr.base);
@@ -1315,6 +1317,9 @@ static void enter_pmode(struct kvm_vcpu *vcpu)
 
         update_exception_bitmap(vcpu);
 
+        if (emulate_invalid_guest_state)
+                return;
+
         fix_pmode_dataseg(VCPU_SREG_ES, &vcpu->arch.rmode.es);
         fix_pmode_dataseg(VCPU_SREG_DS, &vcpu->arch.rmode.ds);
         fix_pmode_dataseg(VCPU_SREG_GS, &vcpu->arch.rmode.gs);
@@ -1355,7 +1360,9 @@ static void fix_rmode_seg(int seg, struct kvm_save_segment *save)
 static void enter_rmode(struct kvm_vcpu *vcpu)
 {
         unsigned long flags;
+        struct vcpu_vmx *vmx = to_vmx(vcpu);
 
+        vmx->emulation_required = 1;
         vcpu->arch.rmode.active = 1;
 
         vcpu->arch.rmode.tr.base = vmcs_readl(GUEST_TR_BASE);
@@ -1377,6 +1384,9 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
         vmcs_writel(GUEST_CR4, vmcs_readl(GUEST_CR4) | X86_CR4_VME);
         update_exception_bitmap(vcpu);
 
+        if (emulate_invalid_guest_state)
+                goto continue_rmode;
+
         vmcs_write16(GUEST_SS_SELECTOR, vmcs_readl(GUEST_SS_BASE) >> 4);
         vmcs_write32(GUEST_SS_LIMIT, 0xffff);
         vmcs_write32(GUEST_SS_AR_BYTES, 0xf3);
@@ -1392,6 +1402,7 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
         fix_rmode_seg(VCPU_SREG_GS, &vcpu->arch.rmode.gs);
         fix_rmode_seg(VCPU_SREG_FS, &vcpu->arch.rmode.fs);
 
+continue_rmode:
         kvm_mmu_reset_context(vcpu);
         init_rmode(vcpu->kvm);
 }
@@ -2317,6 +2328,9 @@ static int vmx_vcpu_reset(struct kvm_vcpu *vcpu)
 
         ret = 0;
 
+        /* HACK: Don't enable emulation on guest boot/reset */
+        vmx->emulation_required = 0;
+
 out:
         up_read(&vcpu->kvm->slots_lock);
         return ret;
@@ -3190,6 +3204,12 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
         struct vcpu_vmx *vmx = to_vmx(vcpu);
         u32 intr_info;
 
+        /* Handle invalid guest state instead of entering VMX */
+        if (vmx->emulation_required && emulate_invalid_guest_state) {
+                handle_invalid_guest_state(vcpu, kvm_run);
+                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))