According to Intel SDM Vol3 Section 5.5 "Privilege Levels" and 5.6
"Privilege Level Checking When Accessing Data Segments" RPL checking is
done during loading of a segment selector, not during data access. We
already do checking during segment selector loading, so drop the check
during data access. Checking RPL during data access triggers #GP if
after transition from real mode to protected mode RPL bits in a segment
selector are set.
Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
---
arch/x86/kvm/emulate.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index c7547b3..a3d31e3 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -665,7 +665,7 @@ static int __linearize(struct x86_emulate_ctxt *ctxt,
ulong la;
u32 lim;
u16 sel;
- unsigned cpl, rpl;
+ unsigned cpl;
la = seg_base(ctxt, addr.seg) + addr.ea;
switch (ctxt->mode) {
@@ -699,11 +699,6 @@ static int __linearize(struct x86_emulate_ctxt *ctxt,
goto bad;
}
cpl = ctxt->ops->cpl(ctxt);
- if (ctxt->mode == X86EMUL_MODE_REAL)
- rpl = 0;
- else
- rpl = sel & 3;
- cpl = max(cpl, rpl);
if (!(desc.type & 8)) {
/* data segment */
if (cpl > desc.dpl)
--
1.7.10.4
--
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