linux-kernel - [PATCH v6 6/6] KVM: arm64: Expose guest stage-2 pagetable config to debugfs

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Date: Tue, 20 Feb 2024 15:10:35 +0000
From: Sebastian Ene <sebastianene@...gle.com>
To: catalin.marinas@....com, gshan@...hat.com, james.morse@....com, 
	mark.rutland@....com, maz@...nel.org, oliver.upton@...ux.dev, 
	rananta@...gle.com, ricarkol@...gle.com, ryan.roberts@....com, 
	shahuang@...hat.com, suzuki.poulose@....com, will@...nel.org, 
	yuzenghui@...wei.com
Cc: kvmarm@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, kernel-team@...roid.com, vdonnefort@...gle.com, 
	Sebastian Ene <sebastianene@...gle.com>
Subject: [PATCH v6 6/6] KVM: arm64: Expose guest stage-2 pagetable config to debugfs

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@...gle.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