Alexandru Elisei <[email protected]> writes:
> Hi Jack,
>
> On Fri, Jun 12, 2026 at 05:23:50PM +0100, Jack Thomson wrote:
>> From: Jack Thomson <[email protected]>
....
>> + if (kvm_is_error_hva(hva)) {
>> + ret = -EFAULT;
>> + goto out;
>> + }
>> +
>> + s2fd.hva = hva;
>> + ret = user_mem_abort(&s2fd);
>
> If is_protected_kvm_enabled(), this function doesn't check if the mapping
> already exists. user_mem_abort() will call **p**kvm_pgtable_stage2_map()
> (emphasis is mine) to create the mapping, and pkvm_pgtable_stage2_map() will
> return -EAGAIN, and keep returning -EAGAIN until the mapping is destroyed,
> which
> might be some time away.
>
> Same thing happens **without** pKVM, kvm_pgtable_stage2_map() will return
> -EAGAIN if the mapping exists. But that's not such a big issue, when the
> user calls KVM_PRE_FAULT_MEMORY on the remaining range
> kvm_pgtable_get_leaf() will detect the existing mapping. Which you have
> already taken into consideration judging by the comment, so all good here.
>
But both gmem_abort() and user_mem_abort() handle -EAGAIN internally, don't
they?
For gmem_abort(), we have:
1692: return ret != -EAGAIN ? ret : 0;
For user_mem_abort(), the call path is:
user_mem_abort()
-> kvm_s2_fault_map()
-> KVM_PGT_FN(kvm_pgtable_stage2_map)(pgt, ...)
and kvm_s2_fault_map() does:
2111: if (ret != -EAGAIN)
return ret;
return 0;
-aneesh
