In tdp_mmu_iter_cond_resched there is a call to tdp_iter_start which
causes the iterator to continue its walk over the paging structure from
the root. This is needed after a yield as paging structure could have
been freed in the interim.
The tdp_iter_start call is not very clear and something of a hack. It
requires exposing tdp_iter fields not used elsewhere in tdp_mmu.c and
the effect is not obvious from the function name. Factor a more aptly
named function out of tdp_iter_start and call it from
tdp_mmu_iter_cond_resched and tdp_iter_start.
No functional change intended.
Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>
---
arch/x86/kvm/mmu/tdp_iter.c | 24 +++++++++++++++++-------
arch/x86/kvm/mmu/tdp_iter.h | 1 +
arch/x86/kvm/mmu/tdp_mmu.c | 4 +---
3 files changed, 19 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_iter.c b/arch/x86/kvm/mmu/tdp_iter.c
index e5f148106e20..f7f94ea65243 100644
--- a/arch/x86/kvm/mmu/tdp_iter.c
+++ b/arch/x86/kvm/mmu/tdp_iter.c
@@ -20,6 +20,21 @@ static gfn_t round_gfn_for_level(gfn_t gfn, int level)
return gfn & -KVM_PAGES_PER_HPAGE(level);
}
+/*
+ * Return the TDP iterator to the root PT and allow it to continue its
+ * traversal over the paging structure from there.
+ */
+void tdp_iter_restart(struct tdp_iter *iter)
+{
+ iter->yielded_gfn = iter->next_last_level_gfn;
+ iter->level = iter->root_level;
+
+ iter->gfn = round_gfn_for_level(iter->next_last_level_gfn, iter->level);
+ tdp_iter_refresh_sptep(iter);
+
+ iter->valid = true;
+}
+
/*
* Sets a TDP iterator to walk a pre-order traversal of the paging structure
* rooted at root_pt, starting with the walk to translate next_last_level_gfn.
@@ -31,16 +46,11 @@ void tdp_iter_start(struct tdp_iter *iter, u64 *root_pt, int root_level,
WARN_ON(root_level > PT64_ROOT_MAX_LEVEL);
iter->next_last_level_gfn = next_last_level_gfn;
- iter->yielded_gfn = iter->next_last_level_gfn;
iter->root_level = root_level;
iter->min_level = min_level;
- iter->level = root_level;
- iter->pt_path[iter->level - 1] = (tdp_ptep_t)root_pt;
+ iter->pt_path[iter->root_level - 1] = (tdp_ptep_t)root_pt;
- iter->gfn = round_gfn_for_level(iter->next_last_level_gfn, iter->level);
- tdp_iter_refresh_sptep(iter);
-
- iter->valid = true;
+ tdp_iter_restart(iter);
}
/*
diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h
index 4cc177d75c4a..8eb424d17c91 100644
--- a/arch/x86/kvm/mmu/tdp_iter.h
+++ b/arch/x86/kvm/mmu/tdp_iter.h
@@ -63,5 +63,6 @@ void tdp_iter_start(struct tdp_iter *iter, u64 *root_pt, int root_level,
int min_level, gfn_t next_last_level_gfn);
void tdp_iter_next(struct tdp_iter *iter);
tdp_ptep_t tdp_iter_root_pt(struct tdp_iter *iter);
+void tdp_iter_restart(struct tdp_iter *iter);
#endif /* __KVM_X86_MMU_TDP_ITER_H */
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 946da74e069c..38b6b6936171 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -664,9 +664,7 @@ static inline bool tdp_mmu_iter_cond_resched(struct kvm *kvm,
WARN_ON(iter->gfn > iter->next_last_level_gfn);
- tdp_iter_start(iter, iter->pt_path[iter->root_level - 1],
- iter->root_level, iter->min_level,
- iter->next_last_level_gfn);
+ tdp_iter_restart(iter);
return true;
}
--
2.31.0.rc2.261.g7f71774620-goog
