linux-kernel - [PATCH 09/11] arm64: ptdump: Interpret memory attributes based on runtime configuration

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Date:   Wed, 27 Sep 2023 11:25:15 +0000
From:   Sebastian Ene <sebastianene@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     kernel-team@...roid.com, will@...nel.org, ryan.roberts@....com,
        mark.rutland@....com, maz@...nel.org, vdonnefort@...gle.com,
        Sebastian Ene <sebastianene@...gle.com>
Subject: [PATCH 09/11] arm64: ptdump: Interpret memory attributes based on
 runtime configuration

When FWB is used the memory attributes stored in the descriptors have a
different bitfield layout. Introduce two callbacks that verify the current
runtime configuration before parsing the attribute fields.
Add support for parsing the memory attribute fields from the page table
descriptors.

Signed-off-by: Sebastian Ene <sebastianene@...gle.com>
---
 arch/arm64/mm/ptdump.c | 67 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 66 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
index c0e7a80992f4..964758d5e76d 100644
--- a/arch/arm64/mm/ptdump.c
+++ b/arch/arm64/mm/ptdump.c
@@ -85,13 +85,22 @@ struct pg_state {
 	bool check_wx;
 	unsigned long wx_pages;
 	unsigned long uxn_pages;
+	struct ptdump_info *info;
 };
 
+/*
+ * This callback checks the runtime configuration before interpreting the
+ * attributes defined in the prot_bits.
+ */
+typedef bool (*is_feature_cb)(const void *ctx);
+
 struct prot_bits {
 	u64		mask;
 	u64		val;
 	const char	*set;
 	const char	*clear;
+	is_feature_cb   feature_on;  /* bit ignored if the callback returns false */
+	is_feature_cb   feature_off; /* bit ignored if the callback returns true */
 };
 
 static const struct prot_bits pte_bits[] = {
@@ -173,6 +182,34 @@ static const struct prot_bits pte_bits[] = {
 	}
 };
 
+static bool is_fwb_enabled(const void *ctx)
+{
+	const struct pg_state *st = ctx;
+	const struct ptdump_info *info = st->info;
+	struct kvm_pgtable_snapshot *snapshot = info->priv;
+	struct kvm_pgtable *pgtable = &snapshot->pgtable;
+
+	bool fwb_enabled = false;
+
+	if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB))
+		fwb_enabled = !(pgtable->flags & KVM_PGTABLE_S2_NOFWB);
+
+	return fwb_enabled;
+}
+
+static bool is_table_bit_ignored(const void *ctx)
+{
+	const struct pg_state *st = ctx;
+
+	if (!(st->current_prot & PTE_VALID))
+		return true;
+
+	if (st->level == CONFIG_PGTABLE_LEVELS)
+		return true;
+
+	return false;
+}
+
 static const struct prot_bits stage2_pte_bits[] = {
 	{
 		.mask	= PTE_VALID,
@@ -214,6 +251,27 @@ static const struct prot_bits stage2_pte_bits[] = {
 		.val	= PTE_TABLE_BIT,
 		.set	= "   ",
 		.clear	= "BLK",
+		.feature_off	= is_table_bit_ignored,
+	}, {
+		.mask	= KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR | PTE_VALID,
+		.val	= PTE_S2_MEMATTR(MT_S2_DEVICE_nGnRE) | PTE_VALID,
+		.set	= "DEVICE/nGnRE",
+		.feature_off	= is_fwb_enabled,
+	}, {
+		.mask	= KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR | PTE_VALID,
+		.val	= PTE_S2_MEMATTR(MT_S2_FWB_DEVICE_nGnRE) | PTE_VALID,
+		.set	= "DEVICE/nGnRE FWB",
+		.feature_on	= is_fwb_enabled,
+	}, {
+		.mask	= KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR | PTE_VALID,
+		.val	= PTE_S2_MEMATTR(MT_S2_NORMAL) | PTE_VALID,
+		.set	= "MEM/NORMAL",
+		.feature_off	= is_fwb_enabled,
+	}, {
+		.mask	= KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR | PTE_VALID,
+		.val	= PTE_S2_MEMATTR(MT_S2_FWB_NORMAL) | PTE_VALID,
+		.set	= "MEM/NORMAL FWB",
+		.feature_on	= is_fwb_enabled,
 	}, {
 		.mask	= KVM_PGTABLE_PROT_SW0,
 		.val	= KVM_PGTABLE_PROT_SW0,
@@ -289,13 +347,19 @@ static struct pg_level stage2_pg_level[] = {
 };
 
 static void dump_prot(struct pg_state *st, const struct prot_bits *bits,
-			size_t num)
+		      size_t num)
 {
 	unsigned i;
 
 	for (i = 0; i < num; i++, bits++) {
 		const char *s;
 
+		if (bits->feature_on && !bits->feature_on(st))
+			continue;
+
+		if (bits->feature_off && bits->feature_off(st))
+			continue;
+
 		if ((st->current_prot & bits->mask) == bits->val)
 			s = bits->set;
 		else
@@ -651,6 +715,7 @@ static void stage2_ptdump_walk(struct seq_file *s, struct ptdump_info *info)
 			.marker		= info->markers,
 			.level		= pgtable->start_level,
 			.pg_level	= &stage2_pg_level[0],
+			.info		= info,
 			.ptdump		= {
 				.note_page	= note_page,
 				.range		= (struct ptdump_range[]) {
-- 
2.42.0.515.g380fc7ccd1-goog