* [PATCH] KVM: x86: do not check CS.DPL against RPL during task switch
@ 2014-08-20 11:24 Paolo Bonzini
0 siblings, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2014-08-20 11:24 UTC (permalink / raw)
To: linux-kernel, kvm; +Cc: namit
This reverts the check added by commit 5045b468037d (KVM: x86: check CS.DPL
against RPL during task switch, 2014-05-15). Although the CS.DPL=CS.RPL
check is mentioned in table 7-1 of the SDM as causing a #TSS exception,
it is not mentioned in table 6-6 that lists "invalid TSS conditions"
which cause #TSS exceptions. In fact it causes some tests to fail, which
pass on bare-metal.
Keep the rest of the commit, since we will find new uses for it in 3.18.
Reported-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/emulate.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index ef117b842334..03954f7900f5 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1491,9 +1491,6 @@ 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;
--
1.8.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH] KVM: x86: do not check CS.DPL against RPL during task switch
@ 2014-08-20 11:20 Paolo Bonzini
0 siblings, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2014-08-20 11:20 UTC (permalink / raw)
To: linux-kernel; +Cc: namit
This reverts the check added by commit 5045b468037d (KVM: x86: check CS.DPL
against RPL during task switch, 2014-05-15). Although the CS.DPL=CS.RPL
check is mentioned in table 7-1 of the SDM as causing a #TSS exception,
it is not mentioned in table 6-6 that lists "invalid TSS conditions"
which cause #TSS exceptions. In fact it causes some tests to fail, which
pass on bare-metal.
Keep the rest of the commit, since we will find new uses for it in 3.18.
Reported-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/emulate.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index ef117b842334..03954f7900f5 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1491,9 +1491,6 @@ 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;
--
1.8.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH] KVM: x86: do not check CS.DPL against RPL during task switch
@ 2014-08-20 11:19 Paolo Bonzini
0 siblings, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2014-08-20 11:19 UTC (permalink / raw)
To: linux-kernel; +Cc: namit
This reverts the check added by commit 5045b468037d (KVM: x86: check CS.DPL
against RPL during task switch, 2014-05-15). Although the CS.DPL=CS.RPL
check is mentioned in table 7-1 of the SDM as causing a #TSS exception,
it is not mentioned in table 6-6 that lists "invalid TSS conditions"
which cause #TSS exceptions. In fact it causes some tests to fail, which
pass on bare-metal.
Keep the rest of the commit, since we will find new uses for it in 3.18.
Reported-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/emulate.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index ef117b842334..03954f7900f5 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1491,9 +1491,6 @@ 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;
--
1.8.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
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