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Subject: Re: [PATCH v3 2/3] xen/privcmd: Add IOCTL_PRIVCMD_DM_OP
To: Paul Durrant <paul.durrant@citrix.com>, xen-devel@lists.xenproject.org,
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Cc: Juergen Gross <jgross@suse.com>
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Date: Mon, 13 Feb 2017 14:11:02 -0500
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> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 5e5c7ae..a33f17e 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -22,6 +22,7 @@
>  #include <linux/pagemap.h>
>  #include <linux/seq_file.h>
>  #include <linux/miscdevice.h>
> +#include <linux/moduleparam.h>
>
>  #include <asm/pgalloc.h>
>  #include <asm/pgtable.h>
> @@ -32,6 +33,7 @@
>  #include <xen/xen.h>
>  #include <xen/privcmd.h>
>  #include <xen/interface/xen.h>
> +#include <xen/interface/hvm/dm_op.h>
>  #include <xen/features.h>
>  #include <xen/page.h>
>  #include <xen/xen-ops.h>
> @@ -43,6 +45,17 @@ MODULE_LICENSE("GPL");
>
>  #define PRIV_VMA_LOCKED ((void *)1)
>
> +unsigned int privcmd_dm_op_max_num = 16;
> +module_param_named(dm_op_max_nr_bufs, privcmd_dm_op_max_num, uint, 0644);
> +MODULE_PARM_DESC(dm_op_max_nr_bufs,
> +		 "Maximum number of buffers per dm_op hypercall");
> +
> +unsigned int privcmd_dm_op_buf_max_size = XEN_PAGE_SIZE;

These need to be static. (I can fix it when committing.)

And I am still not sure about using XEN_PAGE_SIZE. There is no 
dependency in the hypervisor on buffers being page-sized, is there? If 
not, XEN_PAGE_SIZE is here just because it happens to be 4K, which is a 
reasonable value.

How about just setting it to 4096?


-boris