On Sat, Oct 11, 2008 at 11:04 AM, Marcelo Tosatti <[EMAIL PROTECTED]> wrote:
> On Fri, Oct 10, 2008 at 06:11:08PM +0200, xming wrote:
>> Kernel 2.6.27 + kvm-76 on the host really gives some performance boost here.
>> but:
>>
>> When running 2.6.27 compiled with CONFIG_KVM_GUEST=y in the guest, the guest
>> won't start, lot's of segfaults (in the guest) especially udev
>> initializations.
>>
>> unset CONFIG_KVM_GUEST=y, then the guest runs fine
>
> Does the attached work for you?
I was running a bunch of VM's on kvm-75 (gentoo/intel x86_64/virtio
guests) just fine. I upgraded to kvm-77 this morning and the VM's
failed to mount root read-write. I checked the list before digging
too deep and found a reference to this thread. Adding this patch on
top of stock kvm-77 appears to have fixed the issue.
Thanks,
-Al
> Avi, do you have thoughts on how to proceed with pvmmu? Using hypercalls
> instead of faults can still be beneficial (for the first write before
> page goes out of sync, or for non-leaf tables which currently don't go
> oos). But at the current state pvmmu should be slower in most loads.
> Perhaps disable it?
>
> KVM: MMU: sync root on paravirt TLB flush
>
> The pvmmu TLB flush handler should request a root sync, similarly to
> a native read-write CR3.
>
> Signed-off-by: Marcelo Tosatti <[EMAIL PROTECTED]>
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 79cb4a9..7e70e97 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -2747,6 +2747,7 @@ static int kvm_pv_mmu_write(struct kvm_vcpu *vcpu,
> static int kvm_pv_mmu_flush_tlb(struct kvm_vcpu *vcpu)
> {
> kvm_x86_ops->tlb_flush(vcpu);
> + set_bit(KVM_REQ_MMU_SYNC, &vcpu->requests);
> return 1;
> }
>
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