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@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-6-qperret@google.com

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 926fc07..0990fda 100644 (file)
--- 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;
 }