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>

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 50ebc32..0f52135 100644 (file)
--- 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 a90d7e0..d6088b8 100644 (file)
--- 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 b9c2b8e..01f08a6 100644 (file)
--- 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;