From 71e4fbbedc30d6e820a32957668560e60b4b9d96 Mon Sep 17 00:00:00 2001 From: "kaf24@firebug.cl.cam.ac.uk" Date: Wed, 13 Sep 2006 14:46:54 +0100 Subject: [PATCH] [XEN] Allow direct reads of port 0x61 by any guest. Often used by BIOS code which may be executed e.g., when starting an X server. From: Jan Beulich Signed-off-by: Keir Fraser --- xen/arch/x86/traps.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c index c11adb2779..07486ddcdd 100644 --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -1003,7 +1003,21 @@ static inline int admin_io_okay( } /* Check admin limits. Silently fail the access if it is disallowed. */ -#define inb_user(_p, _d, _r) (admin_io_okay(_p, 1, _d, _r) ? inb(_p) : ~0) +static inline unsigned char inb_user( + unsigned int port, struct vcpu *v, struct cpu_user_regs *regs) +{ + /* + * Allow read access to port 0x61. Bit 4 oscillates with period 30us, and + * so it is often used for timing loops in BIOS code. This hack can go + * away when we have separate read/write permission rangesets. + * Note that we could emulate bit 4 instead of directly reading port 0x61, + * but there's not really a good reason to do so. + */ + if ( admin_io_okay(port, 1, v, regs) || (port == 0x61) ) + return inb(port); + return ~0; +} +//#define inb_user(_p, _d, _r) (admin_io_okay(_p, 1, _d, _r) ? inb(_p) : ~0) #define inw_user(_p, _d, _r) (admin_io_okay(_p, 2, _d, _r) ? inw(_p) : ~0) #define inl_user(_p, _d, _r) (admin_io_okay(_p, 4, _d, _r) ? inl(_p) : ~0) #define outb_user(_v, _p, _d, _r) \ -- 2.30.2