[PATCH 1/4] mshv: Support larger memory deposits

[Stanislav Kinsburskii]

Convert hv_call_deposit_pages() into a wrapper supporting arbitrary number
of pages, and use it in the memory deposit code paths.

Signed-off-by: Stanislav Kinsburskii <skinsburskii@xxxxxxxxxxxxxxxxxxx>
---
 drivers/hv/hv_proc.c |   50 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c
index 5f4fd9c3231c..0f84a70def30 100644
--- a/drivers/hv/hv_proc.c
+++ b/drivers/hv/hv_proc.c
@@ -16,7 +16,7 @@
 #define HV_DEPOSIT_MAX (HV_HYP_PAGE_SIZE / sizeof(u64) - 1)
 
 /* Deposits exact number of pages. Must be called with interrupts enabled.  */
-int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
+static int __hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
 {
 	struct page **pages, *page;
 	int *counts;
@@ -108,6 +108,54 @@ int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
 	kfree(counts);
 	return ret;
 }
+
+/**
+ * hv_call_deposit_pages - Deposit memory pages to a partition
+ * @node        : NUMA node from which to allocate pages
+ * @partition_id: Target partition ID to deposit pages to
+ * @num_pages   : Number of pages to deposit
+ *
+ * Deposits memory pages to the specified partition. The deposit is
+ * performed in chunks of HV_DEPOSIT_MAX pages to handle large requests
+ * efficiently.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
+{
+	u32 done;
+	int ret = 0;
+
+	/*
+	 * Do a double deposit for L1VH. This reserves enough memory for
+	 * Hypervisor Hot Restart (HHR).
+	 *
+	 * During HHR, every data structure must be recreated in the new
+	 * ("proto") hypervisor. Memory is required by the proto hypervisor
+	 * to do this work.
+	 *
+	 * For regular L1 partitions, more memory can be requested from the
+	 * root during HHR by sending an asynchronous message. But this is
+	 * not supported for L1VHs. A guest must not be allowed to block
+	 * HHR by refusing to deposit more memory.
+	 *
+	 * So for L1VH a deposit is always required for both current needs
+	 * and future HHR work.
+	 */
+	if (hv_l1vh_partition())
+		num_pages *= 2;
+
+	for (done = 0; done < num_pages; done += HV_DEPOSIT_MAX) {
+		u32 to_deposit = min(num_pages - done, HV_DEPOSIT_MAX);
+
+		ret = __hv_call_deposit_pages(node, partition_id,
+					      to_deposit);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
 EXPORT_SYMBOL_GPL(hv_call_deposit_pages);
 
 int hv_deposit_memory_node(int node, u64 partition_id,