From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: [PATCH v2] introduce grant copy for user land
Date: Mon, 8 Dec 2014 11:02:07 +0000
Message-ID: <5485852F.3080600@citrix.com>
References: <1417536806-22562-1-git-send-email-thanos.makatos@citrix.com>
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To: Thanos Makatos <thanos.makatos@citrix.com>, xen-devel@lists.xenproject.org
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On 02/12/14 16:13, Thanos Makatos wrote:
>  
> +struct gntdev_grant_copy_segment {
> +
> +	union {
> +		/* copy from (to) self to (from) guest */
> +		struct {
> +			/*
> +			 * source address and length
> +			 */
> +			struct iovec iov;
> +
> +			/* the granted page */
> +			uint32_t ref;
> +
> +			/* offset in the granted page */
> +			uint16_t offset;
> +		} self;
> +
> +		/* copy from guest to guest */
> +		struct {
> +			uint16_t len;
> +
> +			struct {
> +				/* the granted page */
> +				uint32_t ref;
> +
> +				/* offset in the granted page */
> +				uint16_t offset;
> +			} src, dst;
> +		} g2g;
> +	};
> +
> +	/* grant copy result (GNTST_XXX) */
> +	int16_t status;
> +};

I asked for this ioctl to mirror the hypercall.

Which looks like:

struct gnttab_copy {
        /* IN parameters. */
        struct {
                union {
                        grant_ref_t ref;
                        xen_pfn_t   gmfn;
                } u;
                domid_t  domid;
                uint16_t offset;
        } source, dest;
        uint16_t      len;
        uint16_t      flags;          /* GNTCOPY_* */
        /* OUT parameters. */
        int16_t       status;
};

i.e., each operation specifies the domid of the source and destination
and whether it includes a ref or a virtual address.

David