From: Andre Przywara <andre.przywara@xxxxxxx>
In the segment descriptor _cache_ the accessed bit is always set
(although it can be cleared in the descriptor itself). Since Intel
checks for this condition on a VMENTRY, set this bit in the AMD path
to enable cross vendor migration.
Cc: stable@xxxxxxxxxx
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
Acked-By: Amit Shah <amit.shah@xxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
---
arch/x86/kvm/svm.c | 41 +++++++++++++++++++++++++++++------------
1 files changed, 29 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 22e88a4..1821c20 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -796,20 +796,37 @@ static void svm_get_segment(struct kvm_vcpu *vcpu,
var->db = (s->attrib >> SVM_SELECTOR_DB_SHIFT) & 1;
var->g = (s->attrib >> SVM_SELECTOR_G_SHIFT) & 1;
- /*
- * SVM always stores 0 for the 'G' bit in the CS selector in
- * the VMCB on a VMEXIT. This hurts cross-vendor migration:
- * Intel's VMENTRY has a check on the 'G' bit.
- */
- if (seg == VCPU_SREG_CS)
+ switch (seg) {
+ case VCPU_SREG_CS:
+ /*
+ * SVM always stores 0 for the 'G' bit in the CS selector in
+ * the VMCB on a VMEXIT. This hurts cross-vendor migration:
+ * Intel's VMENTRY has a check on the 'G' bit.
+ */
var->g = s->limit > 0xfffff;
-
- /*
- * Work around a bug where the busy flag in the tr selector
- * isn't exposed
- */
- if (seg == VCPU_SREG_TR)
+ break;
+ case VCPU_SREG_TR:
+ /*
+ * Work around a bug where the busy flag in the tr selector
+ * isn't exposed
+ */
var->type |= 0x2;
+ break;
+ case VCPU_SREG_DS:
+ case VCPU_SREG_ES:
+ case VCPU_SREG_FS:
+ case VCPU_SREG_GS:
+ /*
+ * The accessed bit must always be set in the segment
+ * descriptor cache, although it can be cleared in the
+ * descriptor, the cached bit always remains at 1. Since
+ * Intel has a check on this, set it here to support
+ * cross-vendor migration.
+ */
+ if (!var->unusable)
+ var->type |= 0x1;
+ break;
+ }
var->unusable = !var->present;
}
--
1.6.0.6
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