On Tue, May 6, 2025 at 6:04 PM Yan Zhao <yan.y.zhao@xxxxxxxxx> wrote:
>
> On Mon, May 05, 2025 at 08:44:26PM +0800, Huang, Kai wrote:
> > On Fri, 2025-05-02 at 16:08 +0300, Kirill A. Shutemov wrote:
> > > +static int tdx_pamt_add(atomic_t *pamt_refcount, unsigned long hpa,
> > > + struct list_head *pamt_pages)
> > > +{
> > > + u64 err;
> > > +
> > > + hpa = ALIGN_DOWN(hpa, SZ_2M);
> > > +
> > > + spin_lock(&pamt_lock);
> >
> > Just curious, Can the lock be per-2M-range?
> Me too.
> Could we introduce smaller locks each covering a 2M range?
>
> And could we deposit 2 pamt pages per-2M hpa range no matter if it's finally
> mapped as a huge page or not?
>
Are you suggesting to keep 2 PAMT pages allocated for each private 2M
page even if it's mapped as a hugepage? It will lead to wastage of
memory of 4 MB per 1GB of guest memory range. For large VM sizes that
will amount to high values.
