Christian Hesse wrote:
>> It may be the cpuid strangeness that Rusty saw. Can you try the
>> attached patch?
>>
>
> No, that does not help.
>
Ah, I see it. The Core processor does not have the STAR msr.
Can you try backing out the attached patch?
--
Do not meddle in the internals of kernels, for they are subtle and quick to
panic.
commit 5c828f83928f186320d74627089122ebc9ea98ce
Author: Avi Kivity <[EMAIL PROTECTED]>
Date: Thu Apr 19 14:28:44 2007 +0300
KVM: VMX: Only save/restore MSR_K6_STAR if necessary
Intel hosts only support syscall/sysret in long more (and only if efer.sce
is enabled), so only reload the related MSR_K6_STAR if the guest will
actually be able to use it.
This reduces vmexit cost by about 500 cycles (6400 -> 5870) on my setup.
Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index b61d4dd..3f43f50 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -323,6 +323,16 @@ static void setup_msrs(struct kvm_vcpu *vcpu)
nr_skip = NR_64BIT_MSRS;
nr_good_msrs = vcpu->nmsrs - nr_skip;
+ /*
+ * MSR_K6_STAR is only needed on long mode guests, and only
+ * if efer.sce is enabled.
+ */
+ --nr_good_msrs;
+#if CONFIG_X86_64
+ if (is_long_mode(vcpu) && (vcpu->shadow_efer & EFER_SCE))
+ ++nr_good_msrs;
+#endif
+
vmcs_writel(VM_ENTRY_MSR_LOAD_ADDR,
virt_to_phys(vcpu->guest_msrs + nr_skip));
vmcs_writel(VM_EXIT_MSR_STORE_ADDR,
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