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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>
This commit is contained in:
Avi Kivity 2012-06-13 16:29:39 +03:00
parent a14e579f22
commit e919464b53
1 changed files with 8 additions and 5 deletions
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13
arch/x86/kvm/emulate.c
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@ -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;