linux-kernel - [PATCH v6 05/38] KVM: arm64: Avoid free

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Date:   Fri, 19 Mar 2021 10:01:13 +0000
From:   Quentin Perret <qperret@...gle.com>
To:     catalin.marinas@....com, will@...nel.org, maz@...nel.org,
        james.morse@....com, julien.thierry.kdev@...il.com,
        suzuki.poulose@....com
Cc:     android-kvm@...gle.com, seanjc@...gle.com, mate.toth-pal@....com,
        linux-kernel@...r.kernel.org, robh+dt@...nel.org,
        linux-arm-kernel@...ts.infradead.org, kernel-team@...roid.com,
        kvmarm@...ts.cs.columbia.edu, tabba@...gle.com, ardb@...nel.org,
        mark.rutland@....com, dbrazdil@...gle.com, qperret@...gle.com
Subject: [PATCH v6 05/38] KVM: arm64: Avoid free_page() in page-table allocator

Currently, the KVM page-table allocator uses a mix of put_page() and
free_page() calls depending on the context even though page-allocation
is always achieved using variants of __get_free_page().

Make the code consistent by using put_page() throughout, and reduce the
memory management API surface used by the page-table code. This will
ease factoring out page-allocation from pgtable.c, which is a
pre-requisite to creating page-tables at EL2.

Acked-by: Will Deacon <will@...nel.org>
Signed-off-by: Quentin Perret <qperret@...gle.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 926fc07074f5..0990fda19198 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -414,7 +414,7 @@ int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits)
 static int hyp_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 			   enum kvm_pgtable_walk_flags flag, void * const arg)
 {
-	free_page((unsigned long)kvm_pte_follow(*ptep));
+	put_page(virt_to_page(kvm_pte_follow(*ptep)));
 	return 0;
 }
 
@@ -426,7 +426,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
 	};
 
 	WARN_ON(kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker));
-	free_page((unsigned long)pgt->pgd);
+	put_page(virt_to_page(pgt->pgd));
 	pgt->pgd = NULL;
 }
 
@@ -578,7 +578,7 @@ static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level,
 	if (!data->anchor)
 		return 0;
 
-	free_page((unsigned long)kvm_pte_follow(*ptep));
+	put_page(virt_to_page(kvm_pte_follow(*ptep)));
 	put_page(virt_to_page(ptep));
 
 	if (data->anchor == ptep) {
@@ -701,7 +701,7 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	}
 
 	if (childp)
-		free_page((unsigned long)childp);
+		put_page(virt_to_page(childp));
 
 	return 0;
 }
@@ -898,7 +898,7 @@ static int stage2_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	put_page(virt_to_page(ptep));
 
 	if (kvm_pte_table(pte, level))
-		free_page((unsigned long)kvm_pte_follow(pte));
+		put_page(virt_to_page(kvm_pte_follow(pte)));
 
 	return 0;
 }
-- 
2.31.0.rc2.261.g7f71774620-goog