linux-kernel - [PATCH v4 08/10] arm64: ptdump: Interpret memory attributes based on the runtime config

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Message-ID: <20231218135859.2513568-10-sebastianene@google.com>
Date: Mon, 18 Dec 2023 13:58:58 +0000
From: Sebastian Ene <sebastianene@...gle.com>
To: will@...nel.org, Oliver Upton <oliver.upton@...ux.dev>, 
	James Morse <james.morse@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, catalin.marinas@....com, mark.rutland@....com, 
	akpm@...ux-foundation.org, maz@...nel.org
Cc: kvmarm@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, kernel-team@...roid.com, vdonnefort@...gle.com, 
	qperret@...gle.com, smostafa@...gle.com, 
	Sebastian Ene <sebastianene@...gle.com>
Subject: [PATCH v4 08/10] arm64: ptdump: Interpret memory attributes based on
 the runtime config

Introduce two callbacks that verify the current runtime configuration
before parsing the attribute fields. This is used to check when FWB is
enabled which changes the interpretation of the descriptor bits.

Signed-off-by: Sebastian Ene <sebastianene@...gle.com>
---
 arch/arm64/include/asm/ptdump.h |  7 +++++++
 arch/arm64/kvm/ptdump.c         | 32 ++++++++++++++++++++++++++++++++
 arch/arm64/mm/ptdump.c          |  6 ++++++
 3 files changed, 45 insertions(+)

diff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h
index 4e728d2a1..e150fc21f 100644
--- a/arch/arm64/include/asm/ptdump.h
+++ b/arch/arm64/include/asm/ptdump.h
@@ -23,11 +23,18 @@ struct ptdump_info {
 	unsigned long			base_addr;
 };
 
+/* Forward declaration */
+struct pg_state;
+
 struct prot_bits {
 	u64		mask;
 	u64		val;
 	const char	*set;
 	const char	*clear;
+	/* bit ignored if the callback returns false */
+	bool		(*feature_on)(const struct pg_state *ctxt);
+	/* bit ignored if the callback returns true */
+	bool		(*feature_off)(const struct pg_state *ctxt);
 };
 
 struct pg_level {
diff --git a/arch/arm64/kvm/ptdump.c b/arch/arm64/kvm/ptdump.c
index 80c338e03..0ad7944e5 100644
--- a/arch/arm64/kvm/ptdump.c
+++ b/arch/arm64/kvm/ptdump.c
@@ -40,6 +40,18 @@ static struct kvm_pgtable_mm_ops ptdump_host_mmops = {
 	.virt_to_phys	= get_host_pa,
 };
 
+static bool is_fwb_enabled(const struct pg_state *m)
+{
+	struct kvm_pgtable_snapshot *snapshot = m->seq->private;
+	struct kvm_pgtable *pgtable = &snapshot->pgtable;
+	bool fwb_enabled = false;
+
+	if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
+		fwb_enabled = !(pgtable->flags & KVM_PGTABLE_S2_NOFWB);
+
+	return fwb_enabled;
+}
+
 static const struct prot_bits stage2_pte_bits[] = {
 	{
 		.mask	= PTE_VALID,
@@ -81,6 +93,26 @@ static const struct prot_bits stage2_pte_bits[] = {
 		.val	= PTE_TABLE_BIT,
 		.set	= "   ",
 		.clear	= "BLK",
+	}, {
+		.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,
diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
index 015ed65d3..6c7208f66 100644
--- a/arch/arm64/mm/ptdump.c
+++ b/arch/arm64/mm/ptdump.c
@@ -177,6 +177,12 @@ static void dump_prot(struct pg_state *st, const struct prot_bits *bits,
 	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
-- 
2.43.0.472.g3155946c3a-goog