linux-kernel - [PATCH v4 19/21] KVM: arm64: Refactor protected nVHE stage-1 locking

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Message-Id: <20210809152448.1810400-20-qperret@google.com>
Date:   Mon,  9 Aug 2021 16:24:46 +0100
From:   Quentin Perret <qperret@...gle.com>
To:     maz@...nel.org, james.morse@....com, alexandru.elisei@....com,
        suzuki.poulose@....com, catalin.marinas@....com, will@...nel.org
Cc:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, ardb@...nel.org, qwandor@...gle.com,
        tabba@...gle.com, dbrazdil@...gle.com, kernel-team@...roid.com,
        qperret@...gle.com
Subject: [PATCH v4 19/21] KVM: arm64: Refactor protected nVHE stage-1 locking

Refactor the hypervisor stage-1 locking in nVHE protected mode to expose
a new pkvm_create_mappings_locked() function. This will be used in later
patches to allow walking and changing the hypervisor stage-1 without
releasing the lock.

Signed-off-by: Quentin Perret <qperret@...gle.com>
---
 arch/arm64/kvm/hyp/include/nvhe/mm.h |  1 +
 arch/arm64/kvm/hyp/nvhe/mm.c         | 18 ++++++++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/hyp/include/nvhe/mm.h b/arch/arm64/kvm/hyp/include/nvhe/mm.h
index 8ec3a5a7744b..c76d7136ed9b 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mm.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mm.h
@@ -23,6 +23,7 @@ int hyp_map_vectors(void);
 int hyp_back_vmemmap(phys_addr_t phys, unsigned long size, phys_addr_t back);
 int pkvm_cpu_set_vector(enum arm64_hyp_spectre_vector slot);
 int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot);
+int pkvm_create_mappings_locked(void *from, void *to, enum kvm_pgtable_prot prot);
 int __pkvm_create_mappings(unsigned long start, unsigned long size,
 			   unsigned long phys, enum kvm_pgtable_prot prot);
 unsigned long __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
diff --git a/arch/arm64/kvm/hyp/nvhe/mm.c b/arch/arm64/kvm/hyp/nvhe/mm.c
index a8efdf0f9003..6fbe8e8030f6 100644
--- a/arch/arm64/kvm/hyp/nvhe/mm.c
+++ b/arch/arm64/kvm/hyp/nvhe/mm.c
@@ -67,13 +67,15 @@ unsigned long __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
 	return addr;
 }
 
-int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
+int pkvm_create_mappings_locked(void *from, void *to, enum kvm_pgtable_prot prot)
 {
 	unsigned long start = (unsigned long)from;
 	unsigned long end = (unsigned long)to;
 	unsigned long virt_addr;
 	phys_addr_t phys;
 
+	hyp_assert_lock_held(&pkvm_pgd_lock);
+
 	start = start & PAGE_MASK;
 	end = PAGE_ALIGN(end);
 
@@ -81,7 +83,8 @@ int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
 		int err;
 
 		phys = hyp_virt_to_phys((void *)virt_addr);
-		err = __pkvm_create_mappings(virt_addr, PAGE_SIZE, phys, prot);
+		err = kvm_pgtable_hyp_map(&pkvm_pgtable, virt_addr, PAGE_SIZE,
+					  phys, prot);
 		if (err)
 			return err;
 	}
@@ -89,6 +92,17 @@ int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
 	return 0;
 }
 
+int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
+{
+	int ret;
+
+	hyp_spin_lock(&pkvm_pgd_lock);
+	ret = pkvm_create_mappings_locked(from, to, prot);
+	hyp_spin_unlock(&pkvm_pgd_lock);
+
+	return ret;
+}
+
 int hyp_back_vmemmap(phys_addr_t phys, unsigned long size, phys_addr_t back)
 {
 	unsigned long start, end;
-- 
2.32.0.605.g8dce9f2422-goog