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Re: [Xen-devel] [PATCH v5 7/8] libxl/libxc: Move libxl_get_numainfo()'s hypercall buffer management to libxc
- To: Ian Campbell <ian.campbell@xxxxxxxxxx>
- From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
- Date: Fri, 20 Mar 2015 10:59:17 -0400
- Cc: elena.ufimtseva@xxxxxxxxxx, wei.liu2@xxxxxxxxxx, stefano.stabellini@xxxxxxxxxxxxx, andrew.cooper3@xxxxxxxxxx, dario.faggioli@xxxxxxxxxx, ian.jackson@xxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxx, jbeulich@xxxxxxxx, keir@xxxxxxx
- Delivery-date: Fri, 20 Mar 2015 15:01:07 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
On 03/20/2015 10:46 AM, Ian Campbell wrote:
On Fri, 2015-03-20 at 10:31 -0400, Boris Ostrovsky wrote:
On 03/20/2015 09:56 AM, Ian Campbell wrote:
On Thu, 2015-03-19 at 17:54 -0400, Boris Ostrovsky wrote:
diff --git a/tools/libxc/xc_misc.c b/tools/libxc/xc_misc.c
index 411128e..607ae61 100644
--- a/tools/libxc/xc_misc.c
+++ b/tools/libxc/xc_misc.c
@@ -209,22 +209,49 @@ out:
return ret;
}
-int xc_numainfo(xc_interface *xch,
- xc_numainfo_t *put_info)
+int xc_numainfo(xc_interface *xch, unsigned *max_nodes,
+ xc_meminfo_t *meminfo, uint32_t *distance)
{
int ret;
DECLARE_SYSCTL;
+ DECLARE_HYPERCALL_BOUNCE(meminfo, *max_nodes * sizeof(*meminfo),
+ XC_HYPERCALL_BUFFER_BOUNCE_OUT);
+ DECLARE_HYPERCALL_BOUNCE(distance,
+ *max_nodes * *max_nodes * sizeof(*distance),
+ XC_HYPERCALL_BUFFER_BOUNCE_OUT);
- sysctl.cmd = XEN_SYSCTL_numainfo;
+ if (meminfo && distance) {
+ if ((ret = xc_hypercall_bounce_pre(xch, meminfo)))
+ goto out;
+ if ((ret = xc_hypercall_bounce_pre(xch, distance)))
+ goto out;
Same comment about handling NULL as before.
In addition what if only one of meminfo and distance is NULL? Is that
valid or do you need a !!meminfo ^ !!distance check?
I want to treat this as as an error here, which is why I have
} else if (meminfo || distance) {
errno = EINVAL;
return -1;
}
because the hypervisor will only attempt to copy numainfo things when
both are valid. Otherwise (i.e. even if only one is a NULL) it will
assume that this is a request for size. The alternative would be to add
another error there, which I decided not to do.
Sorry, I'd trimmed that bit before I thought of the issue. Yes, what you
had was right (although in general it is nicer to test for parameter
validity first).
I'll flip the test order.
-boris
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