Re: [PATCH 2/8] xen/balloon: Move common memory reservation routines to a module

[Oleksandr Andrushchenko]

On 05/29/2018 09:24 PM, Boris Ostrovsky wrote:
> 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.
Will rework it to be NOp for !CONFIG_XEN_HAVE_PVMMU
> -boris