Subject: [RFC PATCH V4 03/12] HV: Mark vmbus ring buffer visible to host in Isolation VM

From: Tianyu Lan <[email-masked]>
Date: Wed, 7 Jul 2021 11:34:44 -0400

From: Tianyu Lan <[email-masked]>

Mark vmbus ring buffer visible with set_memory_decrypted() when
establish gpadl handle.

Signed-off-by: Tianyu Lan <[email-masked]>
---
 drivers/hv/channel.c   | 38 ++++++++++++++++++++++++++++++++++++--
 include/linux/hyperv.h | 10 ++++++++++
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index f3761c73b074..01048bb07082 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -17,6 +17,7 @@
 #include <linux/hyperv.h>
 #include <linux/uio.h>
 #include <linux/interrupt.h>
+#include <linux/set_memory.h>
 #include <asm/page.h>
 #include <asm/mshyperv.h>
 
@@ -465,7 +466,7 @@ static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
 	struct list_head *curr;
 	u32 next_gpadl_handle;
 	unsigned long flags;
-	int ret = 0;
+	int ret = 0, index;
 
 	next_gpadl_handle =
 		(atomic_inc_return(&vmbus_connection.next_gpadl_handle) - 1);
@@ -474,6 +475,13 @@ static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
 	if (ret)
 		return ret;
 
+	ret = set_memory_decrypted((unsigned long)kbuffer,
+				   HVPFN_UP(size));
+	if (ret) {
+		pr_warn("Failed to set host visibility.\n");
+		return ret;
+	}
+
 	init_completion(&msginfo->waitevent);
 	msginfo->waiting_channel = channel;
 
@@ -539,6 +547,15 @@ static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
 	/* At this point, we received the gpadl created msg */
 	*gpadl_handle = gpadlmsg->gpadl;
 
+	if (type == HV_GPADL_BUFFER)
+		index = 0;
+	else
+		index = channel->gpadl_range[1].gpadlhandle ? 2 : 1;
+
+	channel->gpadl_range[index].size = size;
+	channel->gpadl_range[index].buffer = kbuffer;
+	channel->gpadl_range[index].gpadlhandle = *gpadl_handle;
+
 cleanup:
 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 	list_del(&msginfo->msglistentry);
@@ -549,6 +566,11 @@ static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
 	}
 
 	kfree(msginfo);
+
+	if (ret)
+		set_memory_encrypted((unsigned long)kbuffer,
+				     HVPFN_UP(size));
+
 	return ret;
 }
 
@@ -811,7 +833,7 @@ int vmbus_teardown_gpadl(struct vmbus_channel *channel, u32 gpadl_handle)
 	struct vmbus_channel_gpadl_teardown *msg;
 	struct vmbus_channel_msginfo *info;
 	unsigned long flags;
-	int ret;
+	int ret, i;
 
 	info = kzalloc(sizeof(*info) +
 		       sizeof(struct vmbus_channel_gpadl_teardown), GFP_KERNEL);
@@ -859,6 +881,18 @@ int vmbus_teardown_gpadl(struct vmbus_channel *channel, u32 gpadl_handle)
 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 
 	kfree(info);
+
+	/* Find gpadl buffer virtual address and size. */
+	for (i = 0; i < VMBUS_GPADL_RANGE_COUNT; i++)
+		if (channel->gpadl_range[i].gpadlhandle == gpadl_handle)
+			break;
+
+	if (set_memory_encrypted((unsigned long)channel->gpadl_range[i].buffer,
+			HVPFN_UP(channel->gpadl_range[i].size)))
+		pr_warn("Fail to set mem host visibility.\n");
+
+	channel->gpadl_range[i].gpadlhandle = 0;
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl);
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 2e859d2f9609..06eccaba10c5 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -809,6 +809,14 @@ struct vmbus_device {
 
 #define VMBUS_DEFAULT_MAX_PKT_SIZE 4096
 
+struct vmbus_gpadl_range {
+	u32 gpadlhandle;
+	u32 size;
+	void *buffer;
+};
+
+#define VMBUS_GPADL_RANGE_COUNT		3
+
 struct vmbus_channel {
 	struct list_head listentry;
 
@@ -829,6 +837,8 @@ struct vmbus_channel {
 	struct completion rescind_event;
 
 	u32 ringbuffer_gpadlhandle;
+	/* GPADL_RING and Send/Receive GPADL_BUFFER. */
+	struct vmbus_gpadl_range gpadl_range[VMBUS_GPADL_RANGE_COUNT];
 
 	/* Allocated memory for ring buffer */
 	struct page *ringbuffer_page;
-- 
2.25.1