vfio-ccw: Skip second copy of guest cp to host (62465902) · Commits · 戴 / test

We already pinned/copied/unpinned 2K (256 CCWs) of guest memory to the host space anchored off vfio_ccw_private. There's no need to do that again once we have the length calculated, when we could just copy the section we need to the "permanent" space for the I/O. Signed-off-by:

Eric Farman <farman@linux.ibm.com> Message-Id: <20190618202352.39702-3-farman@linux.ibm.com> Reviewed-by:

Cornelia Huck <cohuck@redhat.com> Reviewed-by:

Farhan Ali <alifm@linux.ibm.com> Signed-off-by:

Cornelia Huck <cohuck@redhat.com>

drivers/s390/cio/vfio_ccw_cp.c

+3 −7

Original line number	Diff line number	Diff line
		@@ -444,7 +444,7 @@ static int ccwchain_loop_tic(struct ccwchain *chain,
		static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
		{
		struct ccwchain *chain;
		int len, ret;
		int len;

		/* Copy the chain from cda to cp, and count the CCWs in it */
		len = ccwchain_calc_length(cda, cp);
		@@ -457,12 +457,8 @@ static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
		return -ENOMEM;
		chain->ch_iova = cda;

		/* Copy the new chain from user. */
		ret = copy_ccw_from_iova(cp, chain->ch_ccw, cda, len);
		if (ret) {
		ccwchain_free(chain);
		return ret;
		}
		/* Copy the actual CCWs into the new chain */
		memcpy(chain->ch_ccw, cp->guest_cp, len * sizeof(struct ccw1));

		/* Loop for tics on this new chain. */
		return ccwchain_loop_tic(chain, cp);

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