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Date: Tue, 20 Feb 2024 15:10:35 +0000
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Subject: [PATCH v6 6/6] KVM: arm64: Expose guest stage-2 pagetable config to debugfs
From: Sebastian Ene <sebastianene@google.com>
To: catalin.marinas@arm.com, gshan@redhat.com, james.morse@arm.com, 
	mark.rutland@arm.com, maz@kernel.org, oliver.upton@linux.dev, 
	rananta@google.com, ricarkol@google.com, ryan.roberts@arm.com, 
	shahuang@redhat.com, suzuki.poulose@arm.com, will@kernel.org, 
	yuzenghui@huawei.com
Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, 
	linux-kernel@vger.kernel.org, kernel-team@android.com, vdonnefort@google.com, 
	Sebastian Ene <sebastianene@google.com>
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Make the start level and the IPA bits properties available in the
virtual machine debugfs directory. Make sure that the KVM structure
doesn't disappear behind our back and keep a reference to the KVM struct
while these files are opened.

Signed-off-by: Sebastian Ene <sebastianene@google.com>
---
 arch/arm64/kvm/ptdump.c | 50 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/arch/arm64/kvm/ptdump.c b/arch/arm64/kvm/ptdump.c
index 2c4e0c122d23..a68a22592e97 100644
--- a/arch/arm64/kvm/ptdump.c
+++ b/arch/arm64/kvm/ptdump.c
@@ -213,8 +213,58 @@ static const struct file_operations kvm_ptdump_guest_fops = {
 	.release	= kvm_ptdump_guest_close,
 };
 
+static int kvm_pgtable_debugfs_show(struct seq_file *m, void *)
+{
+	const struct file *file = m->file;
+	struct kvm_pgtable *pgtable = m->private;
+
+	if (!strcmp(file_dentry(file)->d_iname, "ipa_range"))
+		seq_printf(m, "%2u\n", pgtable->ia_bits);
+	else if (!strcmp(file_dentry(file)->d_iname, "stage2_levels"))
+		seq_printf(m, "%1d\n", pgtable->start_level);
+	return 0;
+}
+
+static int kvm_pgtable_debugfs_open(struct inode *m, struct file *file)
+{
+	struct kvm *kvm = m->i_private;
+	struct kvm_s2_mmu *mmu;
+	struct kvm_pgtable *pgtable;
+	int ret;
+
+	if (!kvm_get_kvm_safe(kvm))
+		return -ENOENT;
+
+	mmu = &kvm->arch.mmu;
+	pgtable = mmu->pgt;
+
+	ret = single_open(file, kvm_pgtable_debugfs_show, pgtable);
+	if (ret < 0)
+		kvm_put_kvm(kvm);
+	return ret;
+}
+
+static int kvm_pgtable_debugfs_close(struct inode *m, struct file *file)
+{
+	struct kvm *kvm = m->i_private;
+
+	kvm_put_kvm(kvm);
+	return single_release(m, file);
+}
+
+static const struct file_operations kvm_pgtable_debugfs_fops = {
+	.open		= kvm_pgtable_debugfs_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= kvm_pgtable_debugfs_close,
+};
+
 void kvm_ptdump_guest_register(struct kvm *kvm)
 {
 	debugfs_create_file("stage2_page_tables", 0400, kvm->debugfs_dentry,
 			    kvm, &kvm_ptdump_guest_fops);
+	debugfs_create_file("ipa_range", 0400, kvm->debugfs_dentry, kvm,
+			    &kvm_pgtable_debugfs_fops);
+	debugfs_create_file("stage2_levels", 0400, kvm->debugfs_dentry,
+			    kvm, &kvm_pgtable_debugfs_fops);
 }
-- 
2.44.0.rc0.258.g7320e95886-goog