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

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Message-ID: <b46960c5-6046-4d71-4b4b-9efe96a9489b@gmail.com>
Date:   Tue, 29 May 2018 21:23:21 +0300
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-media@...r.kernel.org,
        jgross@...e.com, konrad.wilk@...cle.com
Cc:     daniel.vetter@...el.com, dongwon.kim@...el.com,
        matthew.d.roper@...el.com,
        Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: Re: [PATCH 2/8] xen/balloon: Move common memory reservation routines
 to a module



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