Commit 3a78a4f4 authored Dec 20, 2012 by Gleb Natapov Committed by Marcelo Tosatti Jan 02, 2013

KVM: emulator: drop RPL check from linearize() function



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@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

parent 11393a07

arch/x86/kvm/emulate.c

+1 −6

Original line number	Diff line number	Diff line
		@@ -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)

Admin message