Re: [PATCH v3 01/11] KVM: MMU: avoid pte_list_desc running out in kvm_mmu_pte_write

Avi Kivity
2011-09-13T09:51:23Z

On 08/30/2011 05:34 AM, Xiao Guangrong wrote:
> kvm_mmu_pte_write is unsafe since we need to alloc pte_list_desc in the
> function when spte is prefetched, unfortunately, we can not know how many
> spte need to be prefetched on this path, that means we can use out of the
> free pte_list_desc object in the cache, and BUG_ON() is triggered, also some
> path does not fill the cache, such as INS instruction emulated that does not
> trigger page fault
>
> @@ -3716,10 +3735,6 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code,
> goto out;
> }
>
> - r = mmu_topup_memory_caches(vcpu);
> - if (r)
> - goto out;
> -
> er = x86_emulate_instruction(vcpu, cr2, 0, insn, insn_len);
>

Suppose we are out of memory, can't this get us in an endless loop?

return -ENOMEM breaks as out (and kills the guest, likely).

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