1 files changed, 30 insertions, 63 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index cd687395e4e7..27c6ece91da6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3267,54 +3267,6 @@ static u32 get_tss_base_addr(struct kvm_vcpu *vcpu,
         return vcpu->arch.mmu.gva_to_gpa(vcpu, base_addr);
 }
 
-static int load_tss_segment32(struct kvm_vcpu *vcpu,
-                              struct desc_struct *seg_desc,
-                              struct tss_segment_32 *tss)
-{
-        u32 base_addr;
-
-        base_addr = get_tss_base_addr(vcpu, seg_desc);
-
-        return kvm_read_guest(vcpu->kvm, base_addr, tss,
-                              sizeof(struct tss_segment_32));
-}
-
-static int save_tss_segment32(struct kvm_vcpu *vcpu,
-                              struct desc_struct *seg_desc,
-                              struct tss_segment_32 *tss)
-{
-        u32 base_addr;
-
-        base_addr = get_tss_base_addr(vcpu, seg_desc);
-
-        return kvm_write_guest(vcpu->kvm, base_addr, tss,
-                               sizeof(struct tss_segment_32));
-}
-
-static int load_tss_segment16(struct kvm_vcpu *vcpu,
-                              struct desc_struct *seg_desc,
-                              struct tss_segment_16 *tss)
-{
-        u32 base_addr;
-
-        base_addr = get_tss_base_addr(vcpu, seg_desc);
-
-        return kvm_read_guest(vcpu->kvm, base_addr, tss,
-                              sizeof(struct tss_segment_16));
-}
-
-static int save_tss_segment16(struct kvm_vcpu *vcpu,
-                              struct desc_struct *seg_desc,
-                              struct tss_segment_16 *tss)
-{
-        u32 base_addr;
-
-        base_addr = get_tss_base_addr(vcpu, seg_desc);
-
-        return kvm_write_guest(vcpu->kvm, base_addr, tss,
-                               sizeof(struct tss_segment_16));
-}
-
 static u16 get_segment_selector(struct kvm_vcpu *vcpu, int seg)
 {
         struct kvm_segment kvm_seg;
@@ -3472,20 +3424,26 @@ static int load_state_from_tss16(struct kvm_vcpu *vcpu,
 }
 
 static int kvm_task_switch_16(struct kvm_vcpu *vcpu, u16 tss_selector,
-                       struct desc_struct *cseg_desc,
+                       u32 old_tss_base,
                        struct desc_struct *nseg_desc)
 {
         struct tss_segment_16 tss_segment_16;
         int ret = 0;
 
-        if (load_tss_segment16(vcpu, cseg_desc, &tss_segment_16))
+        if (kvm_read_guest(vcpu->kvm, old_tss_base, &tss_segment_16,
+                           sizeof tss_segment_16))
                 goto out;
 
         save_state_to_tss16(vcpu, &tss_segment_16);
-        save_tss_segment16(vcpu, cseg_desc, &tss_segment_16);
 
-        if (load_tss_segment16(vcpu, nseg_desc, &tss_segment_16))
+        if (kvm_write_guest(vcpu->kvm, old_tss_base, &tss_segment_16,
+                            sizeof tss_segment_16))
                 goto out;
+
+        if (kvm_read_guest(vcpu->kvm, get_tss_base_addr(vcpu, nseg_desc),
+                           &tss_segment_16, sizeof tss_segment_16))
+                goto out;
+
         if (load_state_from_tss16(vcpu, &tss_segment_16))
                 goto out;
 
@@ -3495,20 +3453,26 @@ out:
 }
 
 static int kvm_task_switch_32(struct kvm_vcpu *vcpu, u16 tss_selector,
-                       struct desc_struct *cseg_desc,
+                       u32 old_tss_base,
                        struct desc_struct *nseg_desc)
 {
         struct tss_segment_32 tss_segment_32;
         int ret = 0;
 
-        if (load_tss_segment32(vcpu, cseg_desc, &tss_segment_32))
+        if (kvm_read_guest(vcpu->kvm, old_tss_base, &tss_segment_32,
+                           sizeof tss_segment_32))
                 goto out;
 
         save_state_to_tss32(vcpu, &tss_segment_32);
-        save_tss_segment32(vcpu, cseg_desc, &tss_segment_32);
 
-        if (load_tss_segment32(vcpu, nseg_desc, &tss_segment_32))
+        if (kvm_write_guest(vcpu->kvm, old_tss_base, &tss_segment_32,
+                            sizeof tss_segment_32))
+                goto out;
+
+        if (kvm_read_guest(vcpu->kvm, get_tss_base_addr(vcpu, nseg_desc),
+                           &tss_segment_32, sizeof tss_segment_32))
                 goto out;
+
         if (load_state_from_tss32(vcpu, &tss_segment_32))
                 goto out;
 
@@ -3523,16 +3487,20 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason)
         struct desc_struct cseg_desc;
         struct desc_struct nseg_desc;
         int ret = 0;
+        u32 old_tss_base = get_segment_base(vcpu, VCPU_SREG_TR);
+        u16 old_tss_sel = get_segment_selector(vcpu, VCPU_SREG_TR);
 
-        kvm_get_segment(vcpu, &tr_seg, VCPU_SREG_TR);
+        old_tss_base = vcpu->arch.mmu.gva_to_gpa(vcpu, old_tss_base);
 
+        /* FIXME: Handle errors. Failure to read either TSS or their
+         * descriptors should generate a pagefault.
+         */
         if (load_guest_segment_descriptor(vcpu, tss_selector, &nseg_desc))
                 goto out;
 
-        if (load_guest_segment_descriptor(vcpu, tr_seg.selector, &cseg_desc))
+        if (load_guest_segment_descriptor(vcpu, old_tss_sel, &cseg_desc))
                 goto out;
 
-
         if (reason != TASK_SWITCH_IRET) {
                 int cpl;
 
@@ -3550,8 +3518,7 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason)
 
         if (reason == TASK_SWITCH_IRET || reason == TASK_SWITCH_JMP) {
                 cseg_desc.type &= ~(1 << 1); //clear the B flag
-                save_guest_segment_descriptor(vcpu, tr_seg.selector,
-                                              &cseg_desc);
+                save_guest_segment_descriptor(vcpu, old_tss_sel, &cseg_desc);
         }
 
         if (reason == TASK_SWITCH_IRET) {
@@ -3563,10 +3530,10 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason)
         kvm_x86_ops->cache_regs(vcpu);
 
         if (nseg_desc.type & 8)
-                ret = kvm_task_switch_32(vcpu, tss_selector, &cseg_desc,
+                ret = kvm_task_switch_32(vcpu, tss_selector, old_tss_base,
                                          &nseg_desc);
         else
-                ret = kvm_task_switch_16(vcpu, tss_selector, &cseg_desc,
+                ret = kvm_task_switch_16(vcpu, tss_selector, old_tss_base,
                                          &nseg_desc);
 
         if (reason == TASK_SWITCH_CALL || reason == TASK_SWITCH_GATE) {