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Date: Thu, 15 May 2014 18:51:30 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: jan.kiszka@...mens.com, kvm@...r.kernel.org, gleb@...nel.org,
avi.kivity@...il.com
Subject: [PATCH v2 3/4] KVM: x86: check CS.DPL against RPL during task switch
Table 7-1 of the SDM mentions a check that the code segment's
DPL must match the selector's RPL. This was not done by KVM,
fix it.
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
arch/x86/kvm/emulate.c | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 47e716ef46b7..2fa7ab069817 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1411,7 +1411,7 @@ static int write_segment_descriptor(struct x86_emulate_ctxt *ctxt,
/* Does not support long mode */
static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
- u16 selector, int seg, u8 cpl)
+ u16 selector, int seg, u8 cpl, bool in_task_switch)
{
struct desc_struct seg_desc, old_desc;
u8 dpl, rpl;
@@ -1486,6 +1486,9 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
goto exception;
break;
case VCPU_SREG_CS:
+ if (in_task_switch && rpl != dpl)
+ goto exception;
+
if (!(seg_desc.type & 8))
goto exception;
@@ -1547,7 +1550,7 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
u16 selector, int seg)
{
u8 cpl = ctxt->ops->cpl(ctxt);
- return __load_segment_descriptor(ctxt, selector, seg, cpl);
+ return __load_segment_descriptor(ctxt, selector, seg, cpl, false);
}
static void write_register_operand(struct operand *op)
@@ -2440,19 +2443,19 @@ static int load_state_from_tss16(struct x86_emulate_ctxt *ctxt,
* Now load segment descriptors. If fault happens at this stage
* it is handled in a context of new task
*/
- ret = __load_segment_descriptor(ctxt, tss->ldt, VCPU_SREG_LDTR, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->ldt, VCPU_SREG_LDTR, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
- ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
- ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
- ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
- ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
@@ -2577,25 +2580,25 @@ static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt,
* Now load segment descriptors. If fault happenes at this stage
* it is handled in a context of new task
*/
- ret = __load_segment_descriptor(ctxt, tss->ldt_selector, VCPU_SREG_LDTR, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->ldt_selector, VCPU_SREG_LDTR, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
- ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
- ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
- ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
- ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
- ret = __load_segment_descriptor(ctxt, tss->fs, VCPU_SREG_FS, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->fs, VCPU_SREG_FS, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
- ret = __load_segment_descriptor(ctxt, tss->gs, VCPU_SREG_GS, cpl);
+ ret = __load_segment_descriptor(ctxt, tss->gs, VCPU_SREG_GS, cpl, true);
if (ret != X86EMUL_CONTINUE)
return ret;
--
1.8.3.1
--
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