linux-kernel - [RFC PATCH 05/27] KVM: arm64: Avoid free

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20201117181607.1761516-6-qperret@google.com>
Date:   Tue, 17 Nov 2020 18:15:45 +0000
From:   Quentin Perret <qperret@...gle.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     "moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)" 
        <kvmarm@...ts.cs.columbia.edu>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" 
        <devicetree@...r.kernel.org>, kernel-team@...roid.com,
        android-kvm@...gle.com, Quentin Perret <qperret@...gle.com>
Subject: [RFC PATCH 05/27] 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 consitent by using put_page() throughout, and reduce the
memory management API surface used by the page-table code. This will
ease factoring out page-alloction from pgtable.c, which is a
pre-requisite to creating page-tables at EL2.

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 0271b4a3b9fe..d7122c5eac24 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -410,7 +410,7 @@ 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;
 }
 
@@ -422,7 +422,7 @@ 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;
 }
 
@@ -551,7 +551,7 @@ 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) {
@@ -674,7 +674,7 @@ 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;
 }
@@ -871,7 +871,7 @@ 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;
 }
-- 
2.29.2.299.gdc1121823c-goog