linux-kernel - [PATCH v2 02/43] kvm: arm64: pgtable: Track the number of pages in the entry level

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Date: Fri, 12 Apr 2024 09:42:28 +0100
From: Steven Price <steven.price@....com>
To: kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Suzuki K Poulose <suzuki.poulose@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Marc Zyngier <maz@...nel.org>,
	Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>,
	linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
	Steven Price <steven.price@....com>
Subject: [PATCH v2 02/43] kvm: arm64: pgtable: Track the number of pages in the entry level

From: Suzuki K Poulose <suzuki.poulose@....com>

Keep track of the number of pages allocated for the top level PGD,
rather than computing it everytime (though we need it only twice now).
This will be used later by Arm CCA KVM changes.

Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Steven Price <steven.price@....com>
---
 arch/arm64/include/asm/kvm_pgtable.h | 2 ++
 arch/arm64/kvm/hyp/pgtable.c         | 5 +++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 19278dfe7978..0350c08ada7a 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -362,6 +362,7 @@ static inline bool kvm_pgtable_walk_lock_held(void)
  * struct kvm_pgtable - KVM page-table.
  * @ia_bits:		Maximum input address size, in bits.
  * @start_level:	Level at which the page-table walk starts.
+ * @pgd_pages:		Number of pages in the entry level of the page-table.
  * @pgd:		Pointer to the first top-level entry of the page-table.
  * @mm_ops:		Memory management callbacks.
  * @mmu:		Stage-2 KVM MMU struct. Unused for stage-1 page-tables.
@@ -372,6 +373,7 @@ static inline bool kvm_pgtable_walk_lock_held(void)
 struct kvm_pgtable {
 	u32					ia_bits;
 	s8					start_level;
+	u8					pgd_pages;
 	kvm_pteref_t				pgd;
 	struct kvm_pgtable_mm_ops		*mm_ops;
 
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 3fae5830f8d2..9decff9736ac 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1552,7 +1552,8 @@ int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
 	u32 sl0 = FIELD_GET(VTCR_EL2_SL0_MASK, vtcr);
 	s8 start_level = VTCR_EL2_TGRAN_SL0_BASE - sl0;
 
-	pgd_sz = kvm_pgd_pages(ia_bits, start_level) * PAGE_SIZE;
+	pgt->pgd_pages = kvm_pgd_pages(ia_bits, start_level);
+	pgd_sz = pgt->pgd_pages * PAGE_SIZE;
 	pgt->pgd = (kvm_pteref_t)mm_ops->zalloc_pages_exact(pgd_sz);
 	if (!pgt->pgd)
 		return -ENOMEM;
@@ -1604,7 +1605,7 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt)
 	};
 
 	WARN_ON(kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker));
-	pgd_sz = kvm_pgd_pages(pgt->ia_bits, pgt->start_level) * PAGE_SIZE;
+	pgd_sz = pgt->pgd_pages * PAGE_SIZE;
 	pgt->mm_ops->free_pages_exact(kvm_dereference_pteref(&walker, pgt->pgd), pgd_sz);
 	pgt->pgd = NULL;
 }
-- 
2.34.1