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SubjectRe: [PATCH 2/8] xen/balloon: Move common memory reservation routines to a module
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On 05/25/2018 11:33 AM, Oleksandr Andrushchenko wrote:
> +
> +void xenmem_reservation_va_mapping_update(unsigned long count,
> + struct page **pages,
> + xen_pfn_t *frames)
> +{
> +#ifdef CONFIG_XEN_HAVE_PVMMU
> + int i;
> +
> + for (i = 0; i < count; i++) {
> + struct page *page;
> +
> + page = pages[i];
> + BUG_ON(page == NULL);
> +
> + /*
> + * We don't support PV MMU when Linux and Xen is using
> + * different page granularity.
> + */
> + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
> +
> + if (!xen_feature(XENFEAT_auto_translated_physmap)) {
> + unsigned long pfn = page_to_pfn(page);
> +
> + set_phys_to_machine(pfn, frames[i]);
> +
> + /* Link back into the page tables if not highmem. */
> + if (!PageHighMem(page)) {
> + int ret;
> +
> + ret = HYPERVISOR_update_va_mapping(
> + (unsigned long)__va(pfn << PAGE_SHIFT),
> + mfn_pte(frames[i], PAGE_KERNEL),
> + 0);
> + BUG_ON(ret);
> + }
> + }
> + }
> +#endif
> +}
> +EXPORT_SYMBOL(xenmem_reservation_va_mapping_update);
> +
> +void xenmem_reservation_va_mapping_reset(unsigned long count,
> + struct page **pages)
> +{
> +#ifdef CONFIG_XEN_HAVE_PVMMU
> + int i;
> +
> + for (i = 0; i < count; i++) {
> + /*
> + * We don't support PV MMU when Linux and Xen is using
> + * different page granularity.
> + */
> + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
> +
> + if (!xen_feature(XENFEAT_auto_translated_physmap)) {
> + struct page *page = pages[i];
> + unsigned long pfn = page_to_pfn(page);
> +
> + if (!PageHighMem(page)) {
> + int ret;
> +
> + ret = HYPERVISOR_update_va_mapping(
> + (unsigned long)__va(pfn << PAGE_SHIFT),
> + __pte_ma(0), 0);
> + BUG_ON(ret);
> + }
> + __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
> + }
> + }
> +#endif
> +}
> +EXPORT_SYMBOL(xenmem_reservation_va_mapping_reset);

One other thing I noticed --- both of these can be declared as NOPs in
the header file if !CONFIG_XEN_HAVE_PVMMU.

-boris

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