xen: use errno instead of rc for xc_domain_add_to_physmap

In Xen 4.6 commit cd2f100f0f61b3f333d52d1737dd73f02daee592
"libxc: Fix do_memory_op to return negative value on errors"
made the libxc API less odd-ball: On errors, return value is
-1 and error code is in errno. On success the return value
is either 0 or an positive value.

Since we could be running with an old toolstack in which the
Exx value is in rc or the newer, we add an wrapper around
the xc_domain_add_to_physmap (called xen_xc_domain_add_to_physmap)
which will always return the EXX.

Xen 4.6 did not change the libxc functions mentioned (same parameters)
so we piggyback on the fact that Xen 4.6 has a new function:
commit 504ed2053362381ac01b98db9313454488b7db40 "tools/libxc: Expose
new hypercall xc_reserved_device_memory_map" and check for that.

Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Suggested-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index 19d0bca14e..d7fa6a4d01 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -417,4 +417,26 @@ static inline int xen_set_ioreq_server_state(XenXC xc, domid_t dom,
 
 #endif
 
+#if CONFIG_XEN_CTRL_INTERFACE_VERSION < 460
+static inline int xen_xc_domain_add_to_physmap(XenXC xch, uint32_t domid,
+                                               unsigned int space,
+                                               unsigned long idx,
+                                               xen_pfn_t gpfn)
+{
+    return xc_domain_add_to_physmap(xch, domid, space, idx, gpfn);
+}
+#else
+static inline int xen_xc_domain_add_to_physmap(XenXC xch, uint32_t domid,
+                                               unsigned int space,
+                                               unsigned long idx,
+                                               xen_pfn_t gpfn)
+{
+    /* In Xen 4.6 rc is -1 and errno contains the error value. */
+    int rc = xc_domain_add_to_physmap(xch, domid, space, idx, gpfn);
+    if (rc == -1)
+        return errno;
+    return rc;
+}
+#endif
+
 #endif /* QEMU_HW_XEN_COMMON_H */