linux-kernel - [PATCH 03/14] KVM: arm64: Directly read owner id field in stage2_pte_is

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Date:   Tue, 30 Aug 2022 19:41:21 +0000
From:   Oliver Upton <oliver.upton@...ux.dev>
To:     Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Quentin Perret <qperret@...gle.com>,
        Ricardo Koller <ricarkol@...gle.com>,
        Reiji Watanabe <reijiw@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Ben Gardon <bgardon@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Gavin Shan <gshan@...hat.com>, Peter Xu <peterx@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Oliver Upton <oliver.upton@...ux.dev>
Cc:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 03/14] KVM: arm64: Directly read owner id field in stage2_pte_is_counted()

A subsequent change to KVM will make use of additional bits in invalid
ptes. Prepare for said change by explicitly checking the valid bit and
owner fields in stage2_pte_is_counted()

Signed-off-by: Oliver Upton <oliver.upton@...ux.dev>
---
 arch/arm64/kvm/hyp/pgtable.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 5c0c8028d71c..b6ce786ae570 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -172,6 +172,11 @@ static kvm_pte_t kvm_init_invalid_leaf_owner(u8 owner_id)
 	return FIELD_PREP(KVM_INVALID_PTE_OWNER_MASK, owner_id);
 }
 
+static u8 kvm_invalid_pte_owner(kvm_pte_t pte)
+{
+	return FIELD_GET(KVM_INVALID_PTE_OWNER_MASK, pte);
+}
+
 static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data, u64 addr,
 				  u32 level, kvm_pte_t *ptep,
 				  enum kvm_pgtable_walk_flags flag)
@@ -679,7 +684,7 @@ static bool stage2_pte_is_counted(kvm_pte_t pte)
 	 * encode ownership of a page to another entity than the page-table
 	 * owner, whose id is 0.
 	 */
-	return !!pte;
+	return kvm_pte_valid(pte) || kvm_invalid_pte_owner(pte);
 }
 
 static void stage2_put_pte(kvm_pte_t *ptep, struct kvm_s2_mmu *mmu, u64 addr,
-- 
2.37.2.672.g94769d06f0-goog