diff mbox series

[04/13] HV: Mark vmbus ring buffer visible to host in Isolation VM

Message ID 20210728145232.285861-5-ltykernel@gmail.com (mailing list archive)
State Superseded
Headers show
Series x86/Hyper-V: Add Hyper-V Isolation VM support | expand

Commit Message

Tianyu Lan July 28, 2021, 2:52 p.m. UTC 
From: Tianyu Lan <Tianyu.Lan@microsoft.com>

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

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

Comments

Joerg Roedel Aug. 2, 2021, 12:07 p.m. UTC | #1 
On Wed, Jul 28, 2021 at 10:52:19AM -0400, Tianyu Lan wrote:
> +	if (type == HV_GPADL_BUFFER)
> +		index = 0;
> +	else
> +		index = channel->gpadl_range[1].gpadlhandle ? 2 : 1;

Hmm... This doesn't look very robust. Can you set fixed indexes for
different buffer types? HV_GPADL_BUFFER already has fixed index 0. But
as it is implemented here you risk that index 2 gets overwritten by
subsequent calls.
Tianyu Lan Aug. 2, 2021, 12:56 p.m. UTC | #2 
On 8/2/2021 8:07 PM, Joerg Roedel wrote:
> On Wed, Jul 28, 2021 at 10:52:19AM -0400, Tianyu Lan wrote:
>> +	if (type == HV_GPADL_BUFFER)
>> +		index = 0;
>> +	else
>> +		index = channel->gpadl_range[1].gpadlhandle ? 2 : 1;
> 
> Hmm... This doesn't look very robust. Can you set fixed indexes for
> different buffer types? HV_GPADL_BUFFER already has fixed index 0. But
> as it is implemented here you risk that index 2 gets overwritten by
> subsequent calls.

Both second and third are HV_GPADL_RING type. One is send ring and the
other is receive ring. The driver keeps the order to allocate rx and
tx buffer. You are right this is not robust and will add a mutex to keep
the order.
Joerg Roedel Aug. 2, 2021, 12:59 p.m. UTC | #3 
On Mon, Aug 02, 2021 at 08:56:29PM +0800, Tianyu Lan wrote:
> Both second and third are HV_GPADL_RING type. One is send ring and the
> other is receive ring. The driver keeps the order to allocate rx and
> tx buffer. You are right this is not robust and will add a mutex to keep
> the order.

Or you introduce fixed indexes for the RX and TX buffers?
Tianyu Lan Aug. 2, 2021, 1:08 p.m. UTC | #4 
On 8/2/2021 8:59 PM, Joerg Roedel wrote:
> On Mon, Aug 02, 2021 at 08:56:29PM +0800, Tianyu Lan wrote:
>> Both second and third are HV_GPADL_RING type. One is send ring and the
>> other is receive ring. The driver keeps the order to allocate rx and
>> tx buffer. You are right this is not robust and will add a mutex to keep
>> the order.
> 
> Or you introduce fixed indexes for the RX and TX buffers?
>

The interface just allocates a buffer and driver will continue to 
configure the buffer to be rx or tx after calling.
diff mbox series

Patch

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;