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9dd060afe2
This patch rolls back some of the changes introduced by commit
121f2faca2 "xen/balloon: rename alloc/free_xenballooned_pages"
in order to make possible to still allocate xenballooned pages
if CONFIG_XEN_UNPOPULATED_ALLOC is enabled.
On Arm the unpopulated pages will be allocated on top of extended
regions provided by Xen via device-tree (the subsequent patches
will add required bits to support unpopulated-alloc feature on Arm).
The problem is that extended regions feature has been introduced
into Xen quite recently (during 4.16 release cycle). So this
effectively means that Linux must only use unpopulated-alloc on Arm
if it is running on "new Xen" which advertises these regions.
But, it will only be known after parsing the "hypervisor" node
at boot time, so before doing that we cannot assume anything.
In order to keep working if CONFIG_XEN_UNPOPULATED_ALLOC is enabled
and the extended regions are not advertised (Linux is running on
"old Xen", etc) we need the fallback to alloc_xenballooned_pages().
This way we wouldn't reduce the amount of memory usable (wasting
RAM pages) for any of the external mappings anymore (and eliminate
XSA-300) with "new Xen", but would be still functional ballooning
out RAM pages with "old Xen".
Also rename alloc(free)_xenballooned_pages to xen_alloc(free)_ballooned_pages
and make xen_alloc(free)_unpopulated_pages static inline in xen.h
if CONFIG_XEN_UNPOPULATED_ALLOC is disabled.
Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/1639080336-26573-4-git-send-email-olekstysh@gmail.com
Signed-off-by: Juergen Gross <jgross@suse.com>
40 lines
1 KiB
C
40 lines
1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/******************************************************************************
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* Xen balloon functionality
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*/
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#ifndef _XEN_BALLOON_H
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#define _XEN_BALLOON_H
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#define RETRY_UNLIMITED 0
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struct balloon_stats {
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/* We aim for 'current allocation' == 'target allocation'. */
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unsigned long current_pages;
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unsigned long target_pages;
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unsigned long target_unpopulated;
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/* Number of pages in high- and low-memory balloons. */
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unsigned long balloon_low;
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unsigned long balloon_high;
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unsigned long total_pages;
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unsigned long schedule_delay;
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unsigned long max_schedule_delay;
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unsigned long retry_count;
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unsigned long max_retry_count;
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};
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extern struct balloon_stats balloon_stats;
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void balloon_set_new_target(unsigned long target);
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int xen_alloc_ballooned_pages(unsigned int nr_pages, struct page **pages);
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void xen_free_ballooned_pages(unsigned int nr_pages, struct page **pages);
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#ifdef CONFIG_XEN_BALLOON
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void xen_balloon_init(void);
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#else
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static inline void xen_balloon_init(void)
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{
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}
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#endif
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#endif /* _XEN_BALLOON_H */
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