Re: [PATCHv2 04/12] x86/virt/tdx: Add tdx_alloc/free_page() helpers

[Adrian Hunter <adrian.hunter@intel.com>]

On 09/06/2025 22:13, Kirill A. Shutemov wrote:
> +static void tdx_pamt_put(struct page *page, enum pg_level level)
> +{
> +	unsigned long hpa = page_to_phys(page);
> +	atomic_t *pamt_refcount;
> +	LIST_HEAD(pamt_pages);
> +	u64 err;
> +
> +	if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
> +		return;
> +
> +	if (level != PG_LEVEL_4K)
> +		return;
> +
> +	hpa = ALIGN_DOWN(hpa, PMD_SIZE);
> +
> +	pamt_refcount = tdx_get_pamt_refcount(hpa);
> +	if (!atomic_dec_and_test(pamt_refcount))
> +		return;
> +
> +	scoped_guard(spinlock, &pamt_lock) {
> +		/* Lost race against tdx_pamt_add()? */
> +		if (atomic_read(pamt_refcount) != 0)
> +			return;
> +
> +		err = tdh_phymem_pamt_remove(hpa | TDX_PS_2M, &pamt_pages);
> +
> +		if (err) {
> +			atomic_inc(pamt_refcount);
> +			pr_err("TDH_PHYMEM_PAMT_REMOVE failed: %#llx\n", err);
> +			return;
> +		}
> +	}
> +

Won't any pages that have been used need to be cleared
before being freed.

> +	tdx_free_pamt_pages(&pamt_pages);
> +}