KVM: emulator: Fix io permission checking for 64bit guest

Current implementation truncates upper 32bit of TR base address during IO
permission bitmap check. The patch fixes this.

Reported-and-tested-by: Francis Moreau <francis.moro@gmail.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

3 files changed, 35 insertions, 21 deletions

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 50ebc327a368..0f5213564326 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -142,9 +142,9 @@ struct x86_emulate_ops {
         int (*pio_out_emulated)(int size, unsigned short port, const void *val,
                                 unsigned int count, struct kvm_vcpu *vcpu);
 
-        bool (*get_cached_descriptor)(struct desc_struct *desc,
+        bool (*get_cached_descriptor)(struct desc_struct *desc, u32 *base3,
                                       int seg, struct kvm_vcpu *vcpu);
-        void (*set_cached_descriptor)(struct desc_struct *desc,
+        void (*set_cached_descriptor)(struct desc_struct *desc, u32 base3,
                                       int seg, struct kvm_vcpu *vcpu);
         u16 (*get_segment_selector)(int seg, struct kvm_vcpu *vcpu);
         void (*set_segment_selector)(u16 sel, int seg, struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a90d7e033304..d6088b8686fb 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -878,7 +878,8 @@ static void get_descriptor_table_ptr(struct x86_emulate_ctxt *ctxt,
         if (selector & 1 << 2) {
                 struct desc_struct desc;
                 memset (dt, 0, sizeof *dt);
-                if (!ops->get_cached_descriptor(&desc, VCPU_SREG_LDTR, ctxt->vcpu))
+                if (!ops->get_cached_descriptor(&desc, NULL, VCPU_SREG_LDTR,
+                                                ctxt->vcpu))
                         return;
 
                 dt->size = desc_limit_scaled(&desc); /* what if limit > 65535? */
@@ -930,6 +931,7 @@ static int write_segment_descriptor(struct x86_emulate_ctxt *ctxt,
         return ret;
 }
 
+/* Does not support long mode */
 static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
                                    struct x86_emulate_ops *ops,
                                    u16 selector, int seg)
@@ -1041,7 +1043,7 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
         }
 load:
         ops->set_segment_selector(selector, seg, ctxt->vcpu);
-        ops->set_cached_descriptor(&seg_desc, seg, ctxt->vcpu);
+        ops->set_cached_descriptor(&seg_desc, 0, seg, ctxt->vcpu);
         return X86EMUL_CONTINUE;
 exception:
         emulate_exception(ctxt, err_vec, err_code, true);
@@ -1561,7 +1563,7 @@ setup_syscalls_segments(struct x86_emulate_ctxt *ctxt,
                         struct desc_struct *ss)
 {
         memset(cs, 0, sizeof(struct desc_struct));
-        ops->get_cached_descriptor(cs, VCPU_SREG_CS, ctxt->vcpu);
+        ops->get_cached_descriptor(cs, NULL, VCPU_SREG_CS, ctxt->vcpu);
         memset(ss, 0, sizeof(struct desc_struct));
 
         cs->l = 0;              /* will be adjusted later */
@@ -1608,9 +1610,9 @@ emulate_syscall(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
                 cs.d = 0;
                 cs.l = 1;
         }
-        ops->set_cached_descriptor(&cs, VCPU_SREG_CS, ctxt->vcpu);
+        ops->set_cached_descriptor(&cs, 0, VCPU_SREG_CS, ctxt->vcpu);
         ops->set_segment_selector(cs_sel, VCPU_SREG_CS, ctxt->vcpu);
-        ops->set_cached_descriptor(&ss, VCPU_SREG_SS, ctxt->vcpu);
+        ops->set_cached_descriptor(&ss, 0, VCPU_SREG_SS, ctxt->vcpu);
         ops->set_segment_selector(ss_sel, VCPU_SREG_SS, ctxt->vcpu);
 
         c->regs[VCPU_REGS_RCX] = c->eip;
@@ -1680,9 +1682,9 @@ emulate_sysenter(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
                 cs.l = 1;
         }
 
-        ops->set_cached_descriptor(&cs, VCPU_SREG_CS, ctxt->vcpu);
+        ops->set_cached_descriptor(&cs, 0, VCPU_SREG_CS, ctxt->vcpu);
         ops->set_segment_selector(cs_sel, VCPU_SREG_CS, ctxt->vcpu);
-        ops->set_cached_descriptor(&ss, VCPU_SREG_SS, ctxt->vcpu);
+        ops->set_cached_descriptor(&ss, 0, VCPU_SREG_SS, ctxt->vcpu);
         ops->set_segment_selector(ss_sel, VCPU_SREG_SS, ctxt->vcpu);
 
         ops->get_msr(ctxt->vcpu, MSR_IA32_SYSENTER_EIP, &msr_data);
@@ -1737,9 +1739,9 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
         cs_sel |= SELECTOR_RPL_MASK;
         ss_sel |= SELECTOR_RPL_MASK;
 
-        ops->set_cached_descriptor(&cs, VCPU_SREG_CS, ctxt->vcpu);
+        ops->set_cached_descriptor(&cs, 0, VCPU_SREG_CS, ctxt->vcpu);
         ops->set_segment_selector(cs_sel, VCPU_SREG_CS, ctxt->vcpu);
-        ops->set_cached_descriptor(&ss, VCPU_SREG_SS, ctxt->vcpu);
+        ops->set_cached_descriptor(&ss, 0, VCPU_SREG_SS, ctxt->vcpu);
         ops->set_segment_selector(ss_sel, VCPU_SREG_SS, ctxt->vcpu);
 
         c->eip = c->regs[VCPU_REGS_RDX];
@@ -1765,24 +1767,29 @@ static bool emulator_io_port_access_allowed(struct x86_emulate_ctxt *ctxt,
                                             u16 port, u16 len)
 {
         struct desc_struct tr_seg;
+        u32 base3;
         int r;
         u16 io_bitmap_ptr;
         u8 perm, bit_idx = port & 0x7;
         unsigned mask = (1 << len) - 1;
+        unsigned long base;
 
-        ops->get_cached_descriptor(&tr_seg, VCPU_SREG_TR, ctxt->vcpu);
+        ops->get_cached_descriptor(&tr_seg, &base3, VCPU_SREG_TR, ctxt->vcpu);
         if (!tr_seg.p)
                 return false;
         if (desc_limit_scaled(&tr_seg) < 103)
                 return false;
-        r = ops->read_std(get_desc_base(&tr_seg) + 102, &io_bitmap_ptr, 2,
-                          ctxt->vcpu, NULL);
+        base = get_desc_base(&tr_seg);
+#ifdef CONFIG_X86_64
+        base |= ((u64)base3) << 32;
+#endif
+        r = ops->read_std(base + 102, &io_bitmap_ptr, 2, ctxt->vcpu, NULL);
         if (r != X86EMUL_CONTINUE)
                 return false;
         if (io_bitmap_ptr + port/8 > desc_limit_scaled(&tr_seg))
                 return false;
-        r = ops->read_std(get_desc_base(&tr_seg) + io_bitmap_ptr + port/8,
-                          &perm, 1, ctxt->vcpu, NULL);
+        r = ops->read_std(base + io_bitmap_ptr + port/8, &perm, 1, ctxt->vcpu,
+                          NULL);
         if (r != X86EMUL_CONTINUE)
                 return false;
         if ((perm >> bit_idx) & mask)
@@ -2127,7 +2134,7 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt,
         }
 
         ops->set_cr(0,  ops->get_cr(0, ctxt->vcpu) | X86_CR0_TS, ctxt->vcpu);
-        ops->set_cached_descriptor(&next_tss_desc, VCPU_SREG_TR, ctxt->vcpu);
+        ops->set_cached_descriptor(&next_tss_desc, 0, VCPU_SREG_TR, ctxt->vcpu);
         ops->set_segment_selector(tss_selector, VCPU_SREG_TR, ctxt->vcpu);
 
         if (has_error_code) {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b9c2b8e6c70c..01f08a65d09b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4162,8 +4162,8 @@ static unsigned long emulator_get_cached_segment_base(int seg,
         return get_segment_base(vcpu, seg);
 }
 
-static bool emulator_get_cached_descriptor(struct desc_struct *desc, int seg,
-                                           struct kvm_vcpu *vcpu)
+static bool emulator_get_cached_descriptor(struct desc_struct *desc, u32 *base3,
+                                           int seg, struct kvm_vcpu *vcpu)
 {
         struct kvm_segment var;
 
@@ -4176,6 +4176,10 @@ static bool emulator_get_cached_descriptor(struct desc_struct *desc, int seg,
                 var.limit >>= 12;
         set_desc_limit(desc, var.limit);
         set_desc_base(desc, (unsigned long)var.base);
+#ifdef CONFIG_X86_64
+        if (base3)
+                *base3 = var.base >> 32;
+#endif
         desc->type = var.type;
         desc->s = var.s;
         desc->dpl = var.dpl;
@@ -4188,8 +4192,8 @@ static bool emulator_get_cached_descriptor(struct desc_struct *desc, int seg,
         return true;
 }
 
-static void emulator_set_cached_descriptor(struct desc_struct *desc, int seg,
-                                           struct kvm_vcpu *vcpu)
+static void emulator_set_cached_descriptor(struct desc_struct *desc, u32 base3,
+                                           int seg, struct kvm_vcpu *vcpu)
 {
         struct kvm_segment var;
 
@@ -4197,6 +4201,9 @@ static void emulator_set_cached_descriptor(struct desc_struct *desc, int seg,
         kvm_get_segment(vcpu, &var, seg);
 
         var.base = get_desc_base(desc);
+#ifdef CONFIG_X86_64
+        var.base |= ((u64)base3) << 32;
+#endif
         var.limit = get_desc_limit(desc);
         if (desc->g)
                 var.limit = (var.limit << 12) | 0xfff;