[PATCH v2 23/26] KVM: x86 emulator: make read_segment_descriptor() return the address

Avi Kivity
2012-06-27T15:20:24Z

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

Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/x86/kvm/emulate.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 7b575ad..99e3df2 100644
--- 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;

--
1.7.11