x86: retrieve keyboard shift status flags from BIOS

Recent Linux tries to make use of this, and has no way of getting at
these bits without Xen assisting it.

There doesn't appear to be a way to obtain the same information from
UEFI.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/xen/arch/x86/platform_hypercall.c b/xen/arch/x86/platform_hypercall.c
index 88880b0d63..d75a83f2bc 100644
--- a/xen/arch/x86/platform_hypercall.c
+++ b/xen/arch/x86/platform_hypercall.c
@@ -29,6 +29,7 @@
 #include <asm/edd.h>
 #include <asm/mtrr.h>
 #include <asm/io_apic.h>
+#include <asm/setup.h>
 #include "cpu/mtrr/mtrr.h"
 #include <xsm/xsm.h>
 
@@ -319,6 +320,18 @@ ret_t do_platform_op(XEN_GUEST_HANDLE(xen_platform_op_t) u_xenpf_op)
                                      u.firmware_info.u.efi_info) )
                 ret = -EFAULT;
             break;
+        case XEN_FW_KBD_SHIFT_FLAGS:
+            ret = -ESRCH;
+            if ( op->u.firmware_info.index != 0 )
+                break;
+
+            op->u.firmware_info.u.kbd_shift_flags = bootsym(kbd_shift_flags);
+
+            ret = 0;
+            if ( copy_field_to_guest(u_xenpf_op, op,
+                                     u.firmware_info.u.kbd_shift_flags) )
+                ret = -EFAULT;
+            break;
         default:
             ret = -EINVAL;
             break;