paravirt: helper to disable all IO space
In a virtual environment, device drivers such as legacy IDE will waste
quite a lot of time probing for their devices which will never appear.
This helper function allows a paravirt implementation to lay claim to
the whole iomem and ioport space, thereby disabling all device drivers
trying to claim IO resources.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c
index faab09a..60e08b9 100644
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -228,6 +228,41 @@
}
core_initcall(print_banner);
+static struct resource reserve_ioports = {
+ .start = 0,
+ .end = IO_SPACE_LIMIT,
+ .name = "paravirt-ioport",
+ .flags = IORESOURCE_IO | IORESOURCE_BUSY,
+};
+
+static struct resource reserve_iomem = {
+ .start = 0,
+ .end = -1,
+ .name = "paravirt-iomem",
+ .flags = IORESOURCE_MEM | IORESOURCE_BUSY,
+};
+
+/*
+ * Reserve the whole legacy IO space to prevent any legacy drivers
+ * from wasting time probing for their hardware. This is a fairly
+ * brute-force approach to disabling all non-virtual drivers.
+ *
+ * Note that this must be called very early to have any effect.
+ */
+int paravirt_disable_iospace(void)
+{
+ int ret;
+
+ ret = request_resource(&ioport_resource, &reserve_ioports);
+ if (ret == 0) {
+ ret = request_resource(&iomem_resource, &reserve_iomem);
+ if (ret)
+ release_resource(&reserve_ioports);
+ }
+
+ return ret;
+}
+
struct paravirt_ops paravirt_ops = {
.name = "bare hardware",
.paravirt_enabled = 0,
