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From: Will Deacon <will@kernel.org>
To: kvmarm@lists.cs.columbia.edu
Cc: kernel-team@android.com, Marc Zyngier <maz@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 15/20] KVM: arm64: Add support for relaxing stage-2 perms in generic page-table code
Date: Thu, 30 Jul 2020 16:34:01 +0100
Message-ID: <20200730153406.25136-16-will@kernel.org> (raw)
In-Reply-To: <20200730153406.25136-1-will@kernel.org>

Add support for relaxing the permissions of a stage-2 mapping (i.e.
adding additional permissions) to the generic page-table code.

Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/kvm_pgtable.h | 17 +++++++++++++++++
 arch/arm64/kvm/pgtable.c             | 20 ++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index e4d99556a22f..36f0e9e88acd 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -198,6 +198,23 @@ kvm_pte_t kvm_pgtable_stage2_mkyoung(void *cookie, u64 addr);
  */
 kvm_pte_t kvm_pgtable_stage2_mkold(void *cookie, u64 addr);
 
+/**
+ * kvm_pgtable_stage2_relax_perms() - Relax the permissions enforced by a
+ *				      page-table entry.
+ * @cookie:	Opaque cookie allocated by kvm_pgtable_stage2_alloc_cookie().
+ * @addr:	Intermediate physical address to identify the page-table entry.
+ * @prot:	Additional permissions to grant for the mapping.
+ *
+ * If there is a valid, leaf page-table entry used to translate @addr, then
+ * relax the permissions in that entry according to the read, write and
+ * execute permissions specified by @prot. No permissions are removed, and
+ * TLB invalidation is performed after updating the entry.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int kvm_pgtable_stage2_relax_perms(void *cookie, u64 addr,
+				   enum kvm_pgtable_prot prot);
+
 /**
  * kvm_pgtable_stage2_is_young() - Test whether a page-table entry has the
  *				   access flag set.
diff --git a/arch/arm64/kvm/pgtable.c b/arch/arm64/kvm/pgtable.c
index eb41f162a36a..14d8a1b2c4c1 100644
--- a/arch/arm64/kvm/pgtable.c
+++ b/arch/arm64/kvm/pgtable.c
@@ -800,6 +800,26 @@ bool kvm_pgtable_stage2_is_young(void *cookie, u64 addr)
 	return !!(pte & KVM_PTE_LEAF_ATTR_LO_S2_AF);
 }
 
+int kvm_pgtable_stage2_relax_perms(void *cookie, u64 addr,
+				   enum kvm_pgtable_prot prot)
+{
+	int ret;
+	struct kvm_pgtable *pgt = cookie;
+	kvm_pte_t set = 0, clr = 0;
+
+	if (prot & KVM_PGTABLE_PROT_R)
+		set |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R;
+
+	if (prot & KVM_PGTABLE_PROT_W)
+		set |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W;
+
+	if (prot & KVM_PGTABLE_PROT_X)
+		clr |= KVM_PTE_LEAF_ATTR_HI_S2_XN;
+
+	ret = stage2_update_leaf_attrs(cookie, addr, 1, set, clr, NULL);
+	kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, pgt->mmu, addr, 0);
+	return ret;
+}
 
 static int stage2_flush_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 			       enum kvm_pgtable_walk_flags flag,
-- 
2.28.0.rc0.142.g3c755180ce-goog

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  parent reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-30 15:33 [PATCH 00/20] KVM: arm64: Rewrite page-table code and fault handling Will Deacon
2020-07-30 15:33 ` [PATCH 01/20] KVM: arm64: Add stand-alone page-table walker infrastructure Will Deacon
2020-07-30 15:33 ` [PATCH 02/20] KVM: arm64: Add support for creating kernel-agnostic stage-1 page tables Will Deacon
2020-07-31  8:14   ` Quentin Perret
2020-07-31  8:19     ` Quentin Perret
2020-07-31  8:22       ` Will Deacon
2020-07-31  8:36         ` Quentin Perret
2020-07-31  9:06           ` Quentin Perret
2020-07-30 15:33 ` [PATCH 03/20] KVM: arm64: Use generic allocator for hyp stage-1 page-tables Will Deacon
2020-07-30 15:33 ` [PATCH 04/20] KVM: arm64: Add support for creating kernel-agnostic stage-2 page tables Will Deacon
2020-07-30 15:33 ` [PATCH 05/20] KVM: arm64: Add support for stage-2 map()/unmap() in generic page-table Will Deacon
2020-07-30 15:33 ` [PATCH 06/20] KVM: arm64: Convert kvm_phys_addr_ioremap() to generic page-table API Will Deacon
2020-07-30 15:33 ` [PATCH 07/20] KVM: arm64: Convert kvm_set_spte_hva() " Will Deacon
2020-07-30 15:33 ` [PATCH 08/20] KVM: arm64: Convert unmap_stage2_range() " Will Deacon
2020-07-30 15:33 ` [PATCH 09/20] KVM: arm64: Add support for stage-2 page-aging in generic page-table Will Deacon
2020-07-30 15:33 ` [PATCH 10/20] KVM: arm64: Convert page-aging and access faults to generic page-table API Will Deacon
2020-07-30 15:33 ` [PATCH 11/20] KVM: arm64: Add support for stage-2 write-protect in generic page-table Will Deacon
2020-07-30 15:33 ` [PATCH 12/20] KVM: arm64: Convert write-protect operation to generic page-table API Will Deacon
2020-07-30 15:33 ` [PATCH 13/20] KVM: arm64: Add support for stage-2 cache flushing in generic page-table Will Deacon
2020-07-30 15:34 ` [PATCH 14/20] KVM: arm64: Convert memslot cache-flushing code to generic page-table API Will Deacon
2020-07-30 15:34 ` Will Deacon [this message]
2020-07-30 15:34 ` [PATCH 16/20] KVM: arm64: Convert user_mem_abort() " Will Deacon
2020-07-30 15:34 ` [PATCH 17/20] KVM: arm64: Check the cookie instead of the pgd when modifying page-table Will Deacon
2020-07-30 15:34 ` [PATCH 18/20] KVM: arm64: Remove unused page-table code Will Deacon
2020-07-30 15:34 ` [PATCH 19/20] KVM: arm64: Remove unused 'pgd' field from 'struct kvm_s2_mmu' Will Deacon
2020-07-30 15:34 ` [PATCH 20/20] KVM: arm64: Don't constrain maximum IPA size based on host configuration Will Deacon
2020-08-03  8:17 ` [PATCH 00/20] KVM: arm64: Rewrite page-table code and fault handling Andrew Jones
2020-08-03 17:12   ` Quentin Perret

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