Re: [PATCH 2/2] KVM: Prevent internal slots from being COWed

[Avi Kivity <avi@redhat.com>]

On 06/21/2010 11:23 PM, Marcelo Tosatti wrote:
> On Mon, Jun 21, 2010 at 11:18:13AM +0300, Avi Kivity wrote:
>    
>> If a process with a memory slot is COWed, the page will change its address
>> (despite having an elevated reference count).  This breaks internal memory
>> slots which have their physical addresses loaded into vmcs registers (see
>> the APIC access memory slot).
>>
>> Signed-off-by: Avi Kivity<avi@redhat.com>
>> ---
>>   arch/x86/kvm/x86.c |    5 +++++
>>   1 files changed, 5 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 33156a3..d9a33e6 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -5633,6 +5633,11 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
>>   				int user_alloc)
>>   {
>>   	int npages = memslot->npages;
>> +	int map_flags = MAP_PRIVATE | MAP_ANONYMOUS;
>> +
>> +	/* Prevent internal slot pages from being moved by fork()/COW. */
>> +	if (memslot->id>= KVM_MEMORY_SLOTS)
>> +		map_flags = MAP_SHARED | MAP_ANONYMOUS;
>>
>>   	/*To keep backward compatibility with older userspace,
>>   	 *x86 needs to hanlde !user_alloc case.
>>      
> Forgot to use map_flags below.
>
>    

Ouch, corrected and applied.

-- 
error compiling committee.c: too many arguments to function