On 23.07.2024 10:02, Oleksii Kurochko wrote:
> On Mon, Jul 22, 2024 at 7:27 PM Julien Grall <jul...@xen.org> wrote:
>>>> On 22/07/2024 15:44, Oleksii Kurochko wrote:
>>> /* Map a 4k page in a fixmap entry */
>>> void set_fixmap(unsigned map, mfn_t mfn, unsigned int flags)
>>> {
>>> pte_t pte;
>>>
>>> pte = mfn_to_xen_entry(mfn, flags);
>>> pte.pte |= PTE_LEAF_DEFAULT;
>>> write_pte(&xen_fixmap[pt_index(0, FIXMAP_ADDR(map))], pte);
>>
>> It would be saner to check if you are not overwriting any existing
>> mapping as otherwise you will probably need a TLB flush.
>>
>>> }
>>>
>>> /* Remove a mapping from a fixmap entry */
>>> void clear_fixmap(unsigned map)
>>> {
>>> pte_t pte = {0};
>>> write_pte(&xen_fixmap[pt_index(0, FIXMAP_ADDR(map))], pte);
>>
>> Don't you need a TLB flush?
>>
> Inside write_pte() there is "sfence.vma".
That's just a fence though, not a TLB flush.
Jan
