[PATCH v4 07/10] KVM: arm64: Walk the pagetable snapshot and parse the ptdump descriptors

[Sebastian Ene]

Define the attributes for the stage-2 pagetables that will be used by
the ptdump parser code to interepret and show the descriptors. Build the
pagetable level description dynamically and use the KVM pagetable walker
to visit the PTEs. Display the number of the bits used by the IPA
address space and the start level.

Signed-off-by: Sebastian Ene <sebastianene at google.com>
---
 arch/arm64/kvm/ptdump.c | 135 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 134 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/ptdump.c b/arch/arm64/kvm/ptdump.c
index e99bab427..80c338e03 100644
--- a/arch/arm64/kvm/ptdump.c
+++ b/arch/arm64/kvm/ptdump.c
@@ -40,6 +40,66 @@ static struct kvm_pgtable_mm_ops ptdump_host_mmops = {
 	.virt_to_phys	= get_host_pa,
 };
 
+static const struct prot_bits stage2_pte_bits[] = {
+	{
+		.mask	= PTE_VALID,
+		.val	= PTE_VALID,
+		.set	= " ",
+		.clear	= "F",
+	}, {
+		.mask	= KVM_PTE_LEAF_ATTR_HI_S2_XN,
+		.val	= KVM_PTE_LEAF_ATTR_HI_S2_XN,
+		.set	= "XN",
+		.clear	= "  ",
+	}, {
+		.mask	= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R,
+		.val	= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R,
+		.set	= "R",
+		.clear	= " ",
+	}, {
+		.mask	= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W,
+		.val	= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W,
+		.set	= "W",
+		.clear	= " ",
+	}, {
+		.mask	= KVM_PTE_LEAF_ATTR_LO_S2_AF,
+		.val	= KVM_PTE_LEAF_ATTR_LO_S2_AF,
+		.set	= "AF",
+		.clear	= "  ",
+	}, {
+		.mask	= PTE_NG,
+		.val	= PTE_NG,
+		.set	= "FnXS",
+		.clear	= "  ",
+	}, {
+		.mask	= PTE_CONT,
+		.val	= PTE_CONT,
+		.set	= "CON",
+		.clear	= "   ",
+	}, {
+		.mask	= PTE_TABLE_BIT,
+		.val	= PTE_TABLE_BIT,
+		.set	= "   ",
+		.clear	= "BLK",
+	}, {
+		.mask	= KVM_PGTABLE_PROT_SW0,
+		.val	= KVM_PGTABLE_PROT_SW0,
+		.set	= "SW0", /* PKVM_PAGE_SHARED_OWNED */
+	}, {
+		.mask   = KVM_PGTABLE_PROT_SW1,
+		.val	= KVM_PGTABLE_PROT_SW1,
+		.set	= "SW1", /* PKVM_PAGE_SHARED_BORROWED */
+	}, {
+		.mask	= KVM_PGTABLE_PROT_SW2,
+		.val	= KVM_PGTABLE_PROT_SW2,
+		.set	= "SW2",
+	}, {
+		.mask   = KVM_PGTABLE_PROT_SW3,
+		.val	= KVM_PGTABLE_PROT_SW3,
+		.set	= "SW3",
+	},
+};
+
 static int kvm_ptdump_open(struct inode *inode, struct file *file)
 {
 	struct kvm_ptdump_register *reg = inode->i_private;
@@ -73,9 +133,82 @@ static int kvm_ptdump_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static int kvm_ptdump_build_levels(struct pg_level *level, unsigned int start_level)
+{
+	static const char * const level_names[] = {"PGD", "PUD", "PMD", "PTE"};
+	int i, j, name_index;
+
+	if (start_level > 2) {
+		pr_err("invalid start_level %u\n", start_level);
+		return -EINVAL;
+	}
+
+	for (i = start_level; i < KVM_PGTABLE_MAX_LEVELS; i++) {
+		name_index = i - start_level;
+		name_index += name_index * start_level;
+
+		level[i].name	= level_names[name_index];
+		level[i].num	= ARRAY_SIZE(stage2_pte_bits);
+		level[i].bits	= stage2_pte_bits;
+
+		for (j = 0; j < level[i].num; j++)
+			level[i].mask |= level[i].bits[j].mask;
+	}
+
+	return 0;
+}
+
+static int kvm_ptdump_visitor(const struct kvm_pgtable_visit_ctx *ctx,
+			      enum kvm_pgtable_walk_flags visit)
+{
+	struct pg_state *st = ctx->arg;
+	struct ptdump_state *pt_st = &st->ptdump;
+
+	note_page(pt_st, ctx->addr, ctx->level, ctx->old);
+	return 0;
+}
+
 static int kvm_ptdump_show(struct seq_file *m, void *)
 {
-	return -EINVAL;
+	u64 ipa_size;
+	char ipa_description[32];
+	struct pg_state st;
+	struct addr_marker ipa_addr_markers[3] = {0};
+	struct pg_level pg_level_descr[KVM_PGTABLE_MAX_LEVELS] = {0};
+	struct kvm_pgtable_snapshot *snapshot = m->private;
+	struct kvm_pgtable *pgtable = &snapshot->pgtable;
+	struct kvm_pgtable_walker walker = (struct kvm_pgtable_walker) {
+		.cb	= kvm_ptdump_visitor,
+		.arg	= &st,
+		.flags	= KVM_PGTABLE_WALK_LEAF,
+	};
+
+	if (kvm_ptdump_build_levels(pg_level_descr, pgtable->start_level) < 0)
+		return -EINVAL;
+
+	snprintf(ipa_description, sizeof(ipa_description),
+		 "IPA bits %2u start lvl %1u", pgtable->ia_bits,
+		 pgtable->start_level);
+
+	ipa_size = BIT(pgtable->ia_bits);
+	ipa_addr_markers[0].name = ipa_description;
+	ipa_addr_markers[1].start_address = ipa_size;
+
+	st = (struct pg_state) {
+		.seq		= m,
+		.marker		= &ipa_addr_markers[0],
+		.level		= -1,
+		.pg_level	= &pg_level_descr[0],
+		.ptdump	= {
+			.note_page	= note_page,
+			.range		= (struct ptdump_range[]) {
+				{0, ipa_size},
+				{0, 0},
+			},
+		},
+	};
+
+	return kvm_pgtable_walk(pgtable, 0, ipa_size, &walker);
 }
 
 static void kvm_ptdump_debugfs_register(struct kvm_ptdump_register *reg,
-- 
2.43.0.472.g3155946c3a-goog