commit c697518a861e6c43b92b848895f9926580ee63c3
author Gleb Natapov <gleb@redhat.com> Thu Feb 18 12:15:01 2010 +0200
committer Marcelo Tosatti <mtosatti@redhat.com> Mon Mar 01 12:36:14 2010 -0300
tree 23c0b9169dfe783bd4615795cd5495f369d42122
parent 6f550484a15ea1b468665cdf59f020bf08ccb292

KVM: Fix segment descriptor loading

Add proper error and permission checking. This patch also change task
switching code to load segment selectors before segment descriptors, like
SDM requires, otherwise permission checking during segment descriptor
loading will be incorrect.

Cc: stable@kernel.org (2.6.33, 2.6.32)
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/emulate.c

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 2db760f..a1a7b27 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1309,7 +1309,7 @@
 	if (rc != 0)
 		return rc;
 
-	rc = kvm_load_segment_descriptor(ctxt->vcpu, (u16)selector, 1, seg);
+	rc = kvm_load_segment_descriptor(ctxt->vcpu, (u16)selector, seg);
 	return rc;
 }
 
@@ -1491,7 +1491,7 @@
 	rc = emulate_pop(ctxt, ops, &cs, c->op_bytes);
 	if (rc)
 		return rc;
-	rc = kvm_load_segment_descriptor(ctxt->vcpu, (u16)cs, 1, VCPU_SREG_CS);
+	rc = kvm_load_segment_descriptor(ctxt->vcpu, (u16)cs, VCPU_SREG_CS);
 	return rc;
 }
 
@@ -2122,12 +2122,11 @@
 		break;
 	case 0x8e: { /* mov seg, r/m16 */
 		uint16_t sel;
-		int type_bits;
-		int err;
 
 		sel = c->src.val;
 
-		if (c->modrm_reg == VCPU_SREG_CS) {
+		if (c->modrm_reg == VCPU_SREG_CS ||
+		    c->modrm_reg > VCPU_SREG_GS) {
 			kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
 			goto done;
 		}
@@ -2135,18 +2134,7 @@
 		if (c->modrm_reg == VCPU_SREG_SS)
 			toggle_interruptibility(ctxt, X86_SHADOW_INT_MOV_SS);
 
-		if (c->modrm_reg <= 5) {
-			type_bits = (c->modrm_reg == 1) ? 9 : 1;
-			err = kvm_load_segment_descriptor(ctxt->vcpu, sel,
-							  type_bits, c->modrm_reg);
-		} else {
-			printk(KERN_INFO "Invalid segreg in modrm byte 0x%02x\n",
-					c->modrm);
-			goto cannot_emulate;
-		}
-
-		if (err < 0)
-			goto cannot_emulate;
+		rc = kvm_load_segment_descriptor(ctxt->vcpu, sel, c->modrm_reg);
 
 		c->dst.type = OP_NONE;  /* Disable writeback. */
 		break;
@@ -2320,11 +2308,9 @@
 	case 0xe9: /* jmp rel */
 		goto jmp;
 	case 0xea: /* jmp far */
-		if (kvm_load_segment_descriptor(ctxt->vcpu, c->src2.val, 9,
-					VCPU_SREG_CS) < 0) {
-			DPRINTF("jmp far: Failed to load CS descriptor\n");
-			goto cannot_emulate;
-		}
+		if (kvm_load_segment_descriptor(ctxt->vcpu, c->src2.val,
+						VCPU_SREG_CS))
+			goto done;
 
 		c->eip = c->src.val;
 		break;