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Re: [PATCH V3 04/13] HV: Mark vmbus ring buffer visible to host in Isolation VM

On 8/13/2021 6:20 AM, Michael Kelley wrote:
@@ -474,6 +482,13 @@ static int __vmbus_establish_gpadl(struct vmbus_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");
Enhance this message a bit.  "Failed to set host visibility for new GPADL\n"
and also output the value of ret.

OK. This looks better. Thanks.

@@ -539,6 +554,10 @@ static int __vmbus_establish_gpadl(struct vmbus_channel 
        /* At this point, we received the gpadl created msg */
        *gpadl_handle = gpadlmsg->gpadl;

+       channel->gpadl_array[index].size = size;
+       channel->gpadl_array[index].buffer = kbuffer;
+       channel->gpadl_array[index].gpadlhandle = *gpadl_handle;
I can see the merits of transparently stashing the memory address and size
that will be needed by vmbus_teardown_gpadl(), so that the callers of
__vmbus_establish_gpadl() don't have to worry about it.  But doing the
stashing transparently is somewhat messy.

Given that the callers are already have memory allocated to save the
GPADL handle, a little refactoring would make for a much cleaner solution.
Instead of having memory allocated for the 32-bit GPADL handle, callers
should allocate the slightly larger struct vmbus_gpadl that you've
defined below.  The calling interfaces can be updated to take a pointer
to this structure instead of a pointer to the 32-bit GPADL handle, and
you can save the memory address and size right along with the GPADL
handle.  This approach touches a few more files, but I think there are
only two callers outside of the channel management code -- netvsc
and hv_uio -- so it's not a big change.

Yes, this is a good suggestion and Will update in the next version.

@@ -859,6 +886,19 @@ int vmbus_teardown_gpadl(struct vmbus_channel *channel, 
u32 gpadl_handle)
        spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);

+       /* Find gpadl buffer virtual address and size. */
+       for (i = 0; i < VMBUS_GPADL_RANGE_COUNT; i++)
+               if (channel->gpadl_array[i].gpadlhandle == gpadl_handle)
+                       break;
+       if (set_memory_encrypted((unsigned long)channel->gpadl_array[i].buffer,
+                       HVPFN_UP(channel->gpadl_array[i].size)))
+               pr_warn("Fail to set mem host visibility.\n");
Enhance this message a bit: "Failed to set host visibility in GPADL teardown\n".
Also output the returned error code to help in debugging any occurrences of
a failure
Yes, agree. Will update.




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