KVM: arm64: ptdump: Initialize parser_state before pgtable walk

If we go through the "need a bigger buffer" path in seq_read_iter(), which
is likely to happen as we're dumping page tables, we will pass the
populated-by-last-run st::parser_state to
kvm_pgtable_walk()/kvm_ptdump_visitor(). As a result, the output of
stage2_page_tables on my box looks like

0x0000000240000000-0x0000000000000000   17179869175G 1
0x0000000000000000-0x0000000000200000           2M 2   R   px ux  AF BLK
0x0000000000200000-0x0000000040000000        1022M 2
0x0000000040000000-0x0000000040200000           2M 2   R W PXNUXN AF BLK
[...]

Fix it by always initializing st::parser_state before starting a new
pgtable walk.

Besides, remove st::range as it's not used by note_page(); remove the
explicit initialization of parser_state::start_address as it will be
initialized in note_page() anyway.

Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
Link: https://patch.msgid.link/20260328053155.12219-1-zenghui.yu@linux.dev
[maz: rebased on top of NV support]
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/kvm/ptdump.c b/arch/arm64/kvm/ptdump.c
index f5753ac37a05c8181e1a38e071bca9d1ab84c001..c9140e22abcf13606b338e7c6270f416b2bd5241 100644 (file)
--- a/arch/arm64/kvm/ptdump.c
+++ b/arch/arm64/kvm/ptdump.c
@@ -24,7 +24,6 @@ struct kvm_ptdump_guest_state {
        struct ptdump_pg_state  parser_state;
        struct addr_marker      ipa_marker[MARKERS_LEN];
        struct ptdump_pg_level  level[KVM_PGTABLE_MAX_LEVELS];
-       struct ptdump_range     range[MARKERS_LEN];
 };
 
 static const struct ptdump_prot_bits stage2_pte_bits[] = {
@@ -132,17 +131,8 @@ static struct kvm_ptdump_guest_state *kvm_ptdump_parser_create(struct kvm_s2_mmu
 
        st->ipa_marker[0].name          = "Guest IPA";
        st->ipa_marker[1].start_address = BIT(pgtable->ia_bits);
-       st->range[0].end                = BIT(pgtable->ia_bits);
 
        st->mmu                         = mmu;
-       st->parser_state = (struct ptdump_pg_state) {
-               .marker         = &st->ipa_marker[0],
-               .level          = -1,
-               .pg_level       = &st->level[0],
-               .ptdump.range   = &st->range[0],
-               .start_address  = 0,
-       };
-
        return st;
 }
 
@@ -152,14 +142,18 @@ static int kvm_ptdump_guest_show(struct seq_file *m, void *unused)
        struct kvm_ptdump_guest_state *st = m->private;
        struct kvm_s2_mmu *mmu = st->mmu;
        struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
-       struct ptdump_pg_state *parser_state = &st->parser_state;
        struct kvm_pgtable_walker walker = (struct kvm_pgtable_walker) {
                .cb     = kvm_ptdump_visitor,
-               .arg    = parser_state,
+               .arg    = &st->parser_state,
                .flags  = KVM_PGTABLE_WALK_LEAF,
        };
 
-       parser_state->seq = m;
+       st->parser_state = (struct ptdump_pg_state) {
+               .marker         = &st->ipa_marker[0],
+               .level          = -1,
+               .pg_level       = &st->level[0],
+               .seq            = m,
+       };
 
        write_lock(&kvm->mmu_lock);
        ret = kvm_pgtable_walk(mmu->pgt, 0, BIT(mmu->pgt->ia_bits), &walker);