[PATCH v2 08/11] arm64: ptdump: Parse the host stage-2 page-tables from the snapshot

Sebastian Ene
2023-10-19T14:41:36Z

Add a walker function which configures ptdump to parse the page-tables
from the snapshot. Convert the physical address of the pagetable's start
address to a host virtual address and use the ptdump walker to parse the
page-table descriptors.

Signed-off-by: Sebastian Ene <sebastianene@google.com>
---
arch/arm64/mm/ptdump.c | 63 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 63 insertions(+)

diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
index 7c78b8994ca1..3ba4848272df 100644
--- a/arch/arm64/mm/ptdump.c
+++ b/arch/arm64/mm/ptdump.c
@@ -479,6 +479,11 @@ static void *ptdump_host_va(phys_addr_t phys)
return __va(phys);
}

+static struct kvm_pgtable_mm_ops host_mmops = {
+ .phys_to_virt = ptdump_host_va,
+ .virt_to_phys = ptdump_host_pa,
+};
+
static size_t stage2_get_pgd_len(void)
{
u64 mmfr0, mmfr1, vtcr;
@@ -604,6 +609,63 @@ static void stage2_ptdump_end_walk(struct ptdump_info *info)
free_pages_exact(snapshot, PAGE_SIZE);
info->priv = NULL;
}
+
+static int stage2_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;
+
+ if (st->pg_level[ctx->level].mask & ctx->old)
+ pt_st->note_page(pt_st, ctx->addr, ctx->level, ctx->old);
+
+ return 0;
+}
+
+static void stage2_ptdump_walk(struct seq_file *s, struct ptdump_info *info)
+{
+ struct kvm_pgtable_snapshot *snapshot = info->priv;
+ struct pg_state st;
+ struct kvm_pgtable *pgtable;
+ u64 start_ipa = 0, end_ipa;
+ struct addr_marker ipa_address_markers[3];
+ struct kvm_pgtable_walker walker = (struct kvm_pgtable_walker) {
+ .cb = stage2_ptdump_visitor,
+ .arg = &st,
+ .flags = KVM_PGTABLE_WALK_LEAF,
+ };
+
+ if (snapshot == NULL || !snapshot->pgtable.pgd)
+ return;
+
+ pgtable = &snapshot->pgtable;
+ pgtable->mm_ops = &host_mmops;
+ end_ipa = BIT(pgtable->ia_bits) - 1;
+
+ memset(&ipa_address_markers[0], 0, sizeof(ipa_address_markers));
+
+ ipa_address_markers[0].start_address = start_ipa;
+ ipa_address_markers[0].name = "IPA start";
+
+ ipa_address_markers[1].start_address = end_ipa;
+ ipa_address_markers[1].name = "IPA end";
+
+ st = (struct pg_state) {
+ .seq = s,
+ .marker = &ipa_address_markers[0],
+ .level = pgtable->start_level - 1,
+ .pg_level = &stage2_pg_level[0],
+ .ptdump = {
+ .note_page = note_page,
+ .range = (struct ptdump_range[]) {
+ {start_ipa, end_ipa},
+ {0, 0},
+ },
+ },
+ };
+
+ kvm_pgtable_walk(pgtable, start_ipa, end_ipa, &walker);
+}
#endif /* CONFIG_NVHE_EL2_PTDUMP_DEBUGFS */

static void __init ptdump_register_host_stage2(void)
@@ -616,6 +678,7 @@ static void __init ptdump_register_host_stage2(void)
.mc_len = host_s2_pgtable_pages(),
.ptdump_prepare_walk = stage2_ptdump_prepare_walk,
.ptdump_end_walk = stage2_ptdump_end_walk,
+ .ptdump_walk = stage2_ptdump_walk,
};

mutex_init(&stage2_kernel_ptdump_info.file_lock);
--
2.42.0.655.g421f12c284-goog