From: Changyuan Lyu <changyuanl@google.com>
Allow users of KHO to cancel the previous preservation by adding the
necessary interfaces to unpreserve folio.
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Co-developed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
---
include/linux/kexec_handover.h | 12 +++++
kernel/kexec_handover.c | 90 +++++++++++++++++++++++++++++-----
2 files changed, 89 insertions(+), 13 deletions(-)
diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h
index cabdff5f50a2..383e9460edb9 100644
--- a/include/linux/kexec_handover.h
+++ b/include/linux/kexec_handover.h
@@ -33,7 +33,9 @@ struct folio;
bool kho_is_enabled(void);
int kho_preserve_folio(struct folio *folio);
+int kho_unpreserve_folio(struct folio *folio);
int kho_preserve_phys(phys_addr_t phys, size_t size);
+int kho_unpreserve_phys(phys_addr_t phys, size_t size);
struct folio *kho_restore_folio(phys_addr_t phys);
int kho_add_subtree(const char *name, void *fdt);
void kho_remove_subtree(void *fdt);
@@ -58,11 +60,21 @@ static inline int kho_preserve_folio(struct folio *folio)
return -EOPNOTSUPP;
}
+static inline int kho_unpreserve_folio(struct folio *folio)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int kho_preserve_phys(phys_addr_t phys, size_t size)
{
return -EOPNOTSUPP;
}
+static inline int kho_unpreserve_phys(phys_addr_t phys, size_t size)
+{
+ return -EOPNOTSUPP;
+}
+
static inline struct folio *kho_restore_folio(phys_addr_t phys)
{
return NULL;
diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c
index 8a4894e8ac71..b2e99aefbb32 100644
--- a/kernel/kexec_handover.c
+++ b/kernel/kexec_handover.c
@@ -136,26 +136,33 @@ static void *xa_load_or_alloc(struct xarray *xa, unsigned long index, size_t sz)
return elm;
}
-static void __kho_unpreserve(struct kho_mem_track *track, unsigned long pfn,
- unsigned long end_pfn)
+static void __kho_unpreserve_order(struct kho_mem_track *track, unsigned long pfn,
+ unsigned int order)
{
struct kho_mem_phys_bits *bits;
struct kho_mem_phys *physxa;
+ const unsigned long pfn_high = pfn >> order;
- while (pfn < end_pfn) {
- const unsigned int order =
- min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn));
- const unsigned long pfn_high = pfn >> order;
+ physxa = xa_load(&track->orders, order);
+ if (!physxa)
+ return;
- physxa = xa_load(&track->orders, order);
- if (!physxa)
- continue;
+ bits = xa_load(&physxa->phys_bits, pfn_high / PRESERVE_BITS);
+ if (!bits)
+ return;
- bits = xa_load(&physxa->phys_bits, pfn_high / PRESERVE_BITS);
- if (!bits)
- continue;
+ clear_bit(pfn_high % PRESERVE_BITS, bits->preserve);
+}
- clear_bit(pfn_high % PRESERVE_BITS, bits->preserve);
+static void __kho_unpreserve(struct kho_mem_track *track, unsigned long pfn,
+ unsigned long end_pfn)
+{
+ unsigned int order;
+
+ while (pfn < end_pfn) {
+ order = min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn));
+
+ __kho_unpreserve_order(track, pfn, order);
pfn += 1 << order;
}
@@ -667,6 +674,30 @@ int kho_preserve_folio(struct folio *folio)
}
EXPORT_SYMBOL_GPL(kho_preserve_folio);
+/**
+ * kho_unpreserve_folio - unpreserve a folio.
+ * @folio: folio to unpreserve.
+ *
+ * Instructs KHO to unpreserve a folio that was preserved by
+ * kho_preserve_folio() before. The provided @folio (pfn and order)
+ * must exactly match a previously preserved folio.
+ *
+ * Return: 0 on success, error code on failure
+ */
+int kho_unpreserve_folio(struct folio *folio)
+{
+ const unsigned long pfn = folio_pfn(folio);
+ const unsigned int order = folio_order(folio);
+ struct kho_mem_track *track = &kho_out.track;
+
+ if (kho_out.finalized)
+ return -EBUSY;
+
+ __kho_unpreserve_order(track, pfn, order);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kho_unpreserve_folio);
+
/**
* kho_preserve_phys - preserve a physically contiguous range across kexec.
* @phys: physical address of the range.
@@ -712,6 +743,39 @@ int kho_preserve_phys(phys_addr_t phys, size_t size)
}
EXPORT_SYMBOL_GPL(kho_preserve_phys);
+/**
+ * kho_unpreserve_phys - unpreserve a physically contiguous range.
+ * @phys: physical address of the range.
+ * @size: size of the range.
+ *
+ * Instructs KHO to unpreserve the memory range from @phys to @phys + @size.
+ * The @phys address must be aligned to @size, and @size must be a
+ * power-of-2 multiple of PAGE_SIZE.
+ * This call must exactly match a granularity at which memory was originally
+ * preserved (either by a `kho_preserve_phys` call with the same `phys` and
+ * `size`). Unpreserving arbitrary sub-ranges of larger preserved blocks is not
+ * supported.
+ *
+ * Return: 0 on success, error code on failure
+ */
+int kho_unpreserve_phys(phys_addr_t phys, size_t size)
+{
+ struct kho_mem_track *track = &kho_out.track;
+ unsigned long pfn = PHYS_PFN(phys);
+ unsigned long end_pfn = PHYS_PFN(phys + size);
+
+ if (kho_out.finalized)
+ return -EBUSY;
+
+ if (!PAGE_ALIGNED(phys) || !PAGE_ALIGNED(size))
+ return -EINVAL;
+
+ __kho_unpreserve(track, pfn, end_pfn);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kho_unpreserve_phys);
+
static int __kho_abort(void)
{
int err = 0;
--
2.50.1.565.gc32cd1483b-goog