From d572929cdd12a60732c3522f7cf011bfa29165cf Mon Sep 17 00:00:00 2001
From: Jeremy Fitzhardinge <jeremy@xensource.com>
Date: Tue, 17 Jul 2007 18:37:04 -0700
Subject: [PATCH] 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>
---
arch/i386/kernel/paravirt.c | 35 +++++++++++++++++++++++++++++++++++
include/asm-i386/paravirt.h | 1 +
2 files changed, 36 insertions(+)
diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c
index faab09abca5e..60e08b9b50a4 100644
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -228,6 +228,41 @@ static int __init print_banner(void)
}
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,
diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index 786856950b1a..690ada22437a 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -262,6 +262,7 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers, void *site, unsigned len)
unsigned paravirt_patch_insns(void *site, unsigned len,
const char *start, const char *end);
+int paravirt_disable_iospace(void);
/*
* This generates an indirect call based on the operation type number.