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[v2,02/24] KVM: arm64: Allow non-coalescable pages in a hyp_pool

Message ID 20220630135747.26983-3-will@kernel.org (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: Introduce pKVM shadow state at EL2 | expand

Commit Message

Will Deacon June 30, 2022, 1:57 p.m. UTC
From: Quentin Perret <qperret@google.com>

All the contiguous pages used to initialize a 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.

Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
 arch/arm64/kvm/hyp/nvhe/page_alloc.c | 5 +++++
 1 file changed, 5 insertions(+)
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diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
index 1ded09fc9b10..0d15227aced8 100644
--- a/arch/arm64/kvm/hyp/nvhe/page_alloc.c
+++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
@@ -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);
 	/* Mark the new head, and insert it */
 	p->order = order;
 	page_add_to_list(p, &pool->free_area[order]);