Re: with kerenl 2.6.27, CONFIG_KVM_GUEST does not work

[Xavier Gnata <xavier.gnata@gmail.com>]

Held Bernhard wrote:
>> Does the attached work for you?
>>
>> 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 <mtosatti@redhat.com>
>>
>> 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;
>>  }
>>     
> This patch works for me (kvm-77, 2.6.27 host and guest)!
>
> kvm-75 works fine, but kvm-76 and kvm-77 (all unpatched) show lot's of
> segfaults in the guest (2.6.26.5 or 2.6.27, x86_64 on host and guest).
>
> Thanks for the patch!
>
> HTH,
> Bernhard
>   
Hi,

Using this patch on a vanilla 2.6.27 kernel, I get this when I try to 
compile it:

arch/x86/kvm/mmu.c: In function ‘kvm_pv_mmu_flush_tlb’:
arch/x86/kvm/mmu.c:2241: error: ‘KVM_REQ_MMU_SYNC’ undeclared (first use 
in this function)
arch/x86/kvm/mmu.c:2241: error: (Each undeclared identifier is reported 
only once
arch/x86/kvm/mmu.c:2241: error: for each function it appears in.)
make[2]: *** [arch/x86/kvm/mmu.o] Error 1

It was fine with kvm-75 but I still not able to start my ubuntu 2.6.27 
guest with kvm 75 qnd kvm 76.
host : vanilla 2.6.27 x86_64
guest : ubuntu 8.10 (2.6.27)

I must be missing a patch somewhere...

Xavier