linux-kernel - [PATCH v3 55/60] arm64: kvm: avoid CONFIG_PGTABLE

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Date:   Tue,  7 Mar 2023 15:05:17 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     linux-arm-kernel@...ts.infradead.org,
        Ard Biesheuvel <ardb@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ryan Roberts <ryan.roberts@....com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Kees Cook <keescook@...omium.org>
Subject: [PATCH v3 55/60] arm64: kvm: avoid CONFIG_PGTABLE_LEVELS for runtime levels

get_user_mapping_size() uses vabits_actual and CONFIG_PGTABLE_LEVELS to
provide the starting point for a table walk. This is fine for LVA, as
the number of translation levels is the same regardless of whether LVA
is enabled. However, with LPA2, this will no longer be the case, so
let's derive the number of levels from the number of VA bits directly.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/arm64/kvm/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index d64be7b5f6692e8b..4e7c0f9a9c286c09 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -663,7 +663,7 @@ static int get_user_mapping_size(struct kvm *kvm, u64 addr)
 		.pgd		= (kvm_pteref_t)kvm->mm->pgd,
 		.ia_bits	= vabits_actual,
 		.start_level	= (KVM_PGTABLE_MAX_LEVELS -
-				   CONFIG_PGTABLE_LEVELS),
+				   ARM64_HW_PGTABLE_LEVELS(pgt.ia_bits)),
 		.mm_ops		= &kvm_user_mm_ops,
 	};
 	kvm_pte_t pte = 0;	/* Keep GCC quiet... */
-- 
2.39.2