[PATCH v2 1/2] Drivers: hv: vmbus: add vmbus_establish_gpadl_caller_decrypted()

[Kameron Carr <kameroncarr@linux.microsoft.com>]

Add a new vmbus_establish_gpadl_caller_decrypted() for callers that want to
decrypt their own buffers. Add a new hv_gpadl_type,
HV_GPADL_BUFFER_DECRYPTED, to communicate the decryption status of the
buffer.

No functional change for existing callers.

Signed-off-by: Kameron Carr <kameroncarr@linux.microsoft.com>
---
 drivers/hv/channel.c   | 27 +++++++++++++++++++++++++--
 include/linux/hyperv.h |  8 +++++++-
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 6821f225248b1..4782f5070bba9 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -40,6 +40,7 @@ static inline u32 hv_gpadl_size(enum hv_gpadl_type type, u32 size)
 {
 	switch (type) {
 	case HV_GPADL_BUFFER:
+	case HV_GPADL_BUFFER_DECRYPTED:
 		return size;
 	case HV_GPADL_RING:
 		/* The size of a ringbuffer must be page-aligned */
@@ -100,6 +101,7 @@ static inline u64 hv_gpadl_hvpfn(enum hv_gpadl_type type, void *kbuffer,
 
 	switch (type) {
 	case HV_GPADL_BUFFER:
+	case HV_GPADL_BUFFER_DECRYPTED:
 		break;
 	case HV_GPADL_RING:
 		if (i == 0)
@@ -460,7 +462,8 @@ static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
 	}
 
 	gpadl->decrypted = !((channel->co_external_memory && type == HV_GPADL_BUFFER) ||
-		(channel->co_ring_buffer && type == HV_GPADL_RING));
+		(channel->co_ring_buffer && type == HV_GPADL_RING) ||
+		(type == HV_GPADL_BUFFER_DECRYPTED));
 	if (gpadl->decrypted) {
 		/*
 		 * The "decrypted" flag being true assumes that set_memory_decrypted() succeeds.
@@ -575,7 +578,7 @@ static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
  * @channel: a channel
  * @kbuffer: from kmalloc or vmalloc
  * @size: page-size multiple
- * @gpadl_handle: some funky thing
+ * @gpadl: output gpadl
  */
 int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
 			  u32 size, struct vmbus_gpadl *gpadl)
@@ -585,6 +588,26 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
 }
 EXPORT_SYMBOL_GPL(vmbus_establish_gpadl);
 
+/*
+ * vmbus_establish_gpadl_caller_decrypted - Establish a GPADL for a buffer
+ * that has already been decrypted by the caller.
+ *
+ * @channel: a channel
+ * @kbuffer: from kmalloc or vmalloc; must already be decrypted by the caller
+ * @size: page-size multiple
+ * @gpadl: output gpadl
+ *
+ * The caller is responsible for re-encrypting the buffer before freeing it.
+ */
+int vmbus_establish_gpadl_caller_decrypted(struct vmbus_channel *channel,
+					   void *kbuffer, u32 size,
+					   struct vmbus_gpadl *gpadl)
+{
+	return __vmbus_establish_gpadl(channel, HV_GPADL_BUFFER_DECRYPTED,
+				       kbuffer, size, 0U, gpadl);
+}
+EXPORT_SYMBOL_GPL(vmbus_establish_gpadl_caller_decrypted);
+
 /**
  * request_arr_init - Allocates memory for the requestor array. Each slot
  * keeps track of the next available slot in the array. Initially, each
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 964f1be8150c5..1146addbb42c4 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -70,7 +70,8 @@
  */
 enum hv_gpadl_type {
 	HV_GPADL_BUFFER,
-	HV_GPADL_RING
+	HV_GPADL_RING,
+	HV_GPADL_BUFFER_DECRYPTED
 };
 
 /* Single-page buffer */
@@ -1205,6 +1206,11 @@ extern int vmbus_establish_gpadl(struct vmbus_channel *channel,
 				      u32 size,
 				      struct vmbus_gpadl *gpadl);
 
+extern int vmbus_establish_gpadl_caller_decrypted(struct vmbus_channel *channel,
+						  void *kbuffer,
+						  u32 size,
+						  struct vmbus_gpadl *gpadl);
+
 extern int vmbus_teardown_gpadl(struct vmbus_channel *channel,
 				     struct vmbus_gpadl *gpadl);
 
-- 
2.45.4