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FROMLIST: KVM: arm64: Allow attaching of non-coalescable pages to a hyp pool

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All the contiguous pages used to initialize a 'struct hyp_pool' are
considered coalescable, which means that the hyp page allocator will
actively try to merge them with their buddies on the hyp_put_page() path.
However, using hyp_put_page() on a page that is not part of the inital
memory range given to a hyp_pool() is currently unsupported.

In order to allow dynamically extending hyp pools at run-time, add a
check to __hyp_attach_page() to allow inserting 'external' pages into
the free-list of order 0. This will be necessary to allow lazy donation
of pages from the host to the hypervisor when allocating guest stage-2
page-table pages at EL2.

Tested-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20221020133827.5541-3-will@kernel.org
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 233587962
Change-Id: Ie417f839ae6d30705847ab3e27e2b3c3ac6ee8dc
This commit is contained in:
Quentin Perret
2022-10-20 14:38:04 +01:00
committed by Will Deacon
parent b58c75b202
commit d10cef530c
1 changed files with 5 additions and 0 deletions
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5
arch/arm64/kvm/hyp/nvhe/page_alloc.c
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@@ -93,11 +93,15 @@ static inline struct hyp_page *node_to_page(struct list_head *node)
static void __hyp_attach_page(struct hyp_pool *pool,
struct hyp_page *p)
{
phys_addr_t phys = hyp_page_to_phys(p);
unsigned short order = p->order;
struct hyp_page *buddy;
memset(hyp_page_to_virt(p), 0, PAGE_SIZE << p->order);
if (phys < pool->range_start || phys >= pool->range_end)
goto insert;
/*
* Only the first struct hyp_page of a high-order page (otherwise known
* as the 'head') should have p->order set. The non-head pages should
@@ -116,6 +120,7 @@ static void __hyp_attach_page(struct hyp_pool *pool,
p = min(p, buddy);
}
insert:
/* Mark the new head, and insert it */
p->order = order;
page_add_to_list(p, &pool->free_area[order]);