Avi, could you apply this patch to kvm.git and linux-2.6.29-rcx? It
fixes cross vendor migration with multithreaded guest applications.
Also the two cross-vendor migration patches (in this very place) from Amit from
October are not in upstream Linux, could you push (or pull-request) them?
Commit-IDs: 397248be81d79a3e03871b05d136e742a737b640
dc2a503e2f2fbab2dca788d49bb7057604db11b4
Thanks,
Andre.
-----------------
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.
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
arch/x86/kvm/svm.c | 23 +++++++++++++++++++++--
1 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 22e88a4..dc5d88f 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -796,20 +796,39 @@ 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;
+ switch (seg) {
/*
* 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)
+ case VCPU_SREG_CS:
var->g = s->limit > 0xfffff;
+ break;
/*
* Work around a bug where the busy flag in the tr selector
* isn't exposed
*/
- if (seg == VCPU_SREG_TR)
+ case VCPU_SREG_TR:
var->type |= 0x2;
+ break;
+
+ /*
+ * 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.
+ */
+ case VCPU_SREG_DS:
+ case VCPU_SREG_ES:
+ case VCPU_SREG_FS:
+ case VCPU_SREG_GS:
+ if (!var->unusable)
+ var->type |= 0x1;
+ break;
+ }
var->unusable = !var->present;
}
--
1.5.2.2
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