Specifically that it indicates passthrough support for PV guests as well
Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
---
CC: Keir Fraser <k...@xen.org>
CC: Jan Beulich <jbeul...@suse.com>
CC: Tim Deegan <t...@xen.org>
CC: Ian Campbell <ian.campb...@citrix.com>
CC: Ian Jackson <ian.jack...@eu.citrix.com>
---
xen/include/public/sysctl.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index 96680eb..cbbeecd 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -89,7 +89,14 @@ DEFINE_XEN_GUEST_HANDLE(xen_sysctl_tbuf_op_t);
/* (x86) The platform supports HVM guests. */
#define _XEN_SYSCTL_PHYSCAP_hvm 0
#define XEN_SYSCTL_PHYSCAP_hvm (1u<<_XEN_SYSCTL_PHYSCAP_hvm)
- /* (x86) The platform supports HVM-guest direct access to I/O devices. */
+ /*
+ * (x86) The platform supports guest direct access to I/O devices.
+ *
+ * Note that this parameter has been misnamed since its introduction, and is
+ * now too baked into APIs and ABIs to change. Despite the "hvm" in its
+ * name, it simply indicates the presence of an enabled IOMMU, allowing for
+ * passthrough of devices to guests, including PV guests.
+ */
#define _XEN_SYSCTL_PHYSCAP_hvm_directio 1
#define XEN_SYSCTL_PHYSCAP_hvm_directio (1u<<_XEN_SYSCTL_PHYSCAP_hvm_directio)
struct xen_sysctl_physinfo {
--
2.1.4
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