Re: KVM swapping with mmu notifiers

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Marcelo Tosatti wrote:
>>  
>> +static void unmap_spte(struct kvm *kvm, u64 *spte)
>> +{
>> +	struct page *page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
>> +	get_page(page);
>> +	rmap_remove(kvm, spte);
>> +	set_shadow_pte(spte, shadow_trap_nonpresent_pte);
>> +	kvm_flush_remote_tlbs(kvm);
>> +	__free_page(page);
>> +}
>> +
>> +void kvm_rmap_unmap_gfn(struct kvm *kvm, gfn_t gfn)
>> +{
>> +	unsigned long *rmapp;
>> +	u64 *spte, *curr_spte;
>> +
>> +	spin_lock(&kvm->mmu_lock);
>> +	gfn = unalias_gfn(kvm, gfn);
>> +	rmapp = gfn_to_rmap(kvm, gfn);
>>     
>
> The alias and memslot maps are protected only by mmap_sem, so you
> should make kvm_set_memory_region/set_memory_alias grab the mmu spinlock
> in addition to mmap_sem in write mode.
>
> kvm_mmu_zap_all() grabs the mmu lock.. that should probably move up into
> the caller.
>
>   

Aren't mmu notifiers called with mmap_sem held for read?

Maybe not from the swap path?

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


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