KVM: x86 emulator: make read_segment_descriptor() return the address

Some operations want to modify the descriptor later on, so save the
address for future use.

Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 7b575ad..99e3df2 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1296,7 +1296,8 @@ static void get_descriptor_table_ptr(struct x86_emulate_ctxt *ctxt,
 
 /* allowed just for 8 bytes segments */
 static int read_segment_descriptor(struct x86_emulate_ctxt *ctxt,
-                                  u16 selector, struct desc_struct *desc)
+                                  u16 selector, struct desc_struct *desc,
+                                  ulong *desc_addr_p)
 {
        struct desc_ptr dt;
        u16 index = selector >> 3;
@@ -1307,7 +1308,7 @@ static int read_segment_descriptor(struct x86_emulate_ctxt *ctxt,
        if (dt.size < index * 8 + 7)
                return emulate_gp(ctxt, selector & 0xfffc);
 
-       addr = dt.address + index * 8;
+       *desc_addr_p = addr = dt.address + index * 8;
        return ctxt->ops->read_std(ctxt, addr, desc, sizeof *desc,
                                   &ctxt->exception);
 }
@@ -1339,6 +1340,7 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
        unsigned err_vec = GP_VECTOR;
        u32 err_code = 0;
        bool null_selector = !(selector & ~0x3); /* 0000-0003 are null */
+       ulong desc_addr;
        int ret;
 
        memset(&seg_desc, 0, sizeof seg_desc);
@@ -1374,7 +1376,7 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
        if (null_selector) /* for NULL selector skip all following checks */
                goto load;
 
-       ret = read_segment_descriptor(ctxt, selector, &seg_desc);
+       ret = read_segment_descriptor(ctxt, selector, &seg_desc, &desc_addr);
        if (ret != X86EMUL_CONTINUE)
                return ret;
 
@@ -2614,13 +2616,14 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt,
        ulong old_tss_base =
                ops->get_cached_segment_base(ctxt, VCPU_SREG_TR);
        u32 desc_limit;
+       ulong desc_addr;
 
        /* FIXME: old_tss_base == ~0 ? */
 
-       ret = read_segment_descriptor(ctxt, tss_selector, &next_tss_desc);
+       ret = read_segment_descriptor(ctxt, tss_selector, &next_tss_desc, &desc_addr);
        if (ret != X86EMUL_CONTINUE)
                return ret;
-       ret = read_segment_descriptor(ctxt, old_tss_sel, &curr_tss_desc);
+       ret = read_segment_descriptor(ctxt, old_tss_sel, &curr_tss_desc, &desc_addr);
        if (ret != X86EMUL_CONTINUE)
                return ret;