[Patch 2/4] x86/hpet: Sanitise HPET ACPI table and warn about multiple tables

[Andrew Cooper <andrew.cooper3@citrix.com>]

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Keir Fraser <keir@xen.org>
CC: Jan Beulich <JBeulich@suse.com>
---
 xen/arch/x86/acpi/boot.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/xen/arch/x86/acpi/boot.c b/xen/arch/x86/acpi/boot.c
index 0e1d570..1f6cbe6 100644
--- a/xen/arch/x86/acpi/boot.c
+++ b/xen/arch/x86/acpi/boot.c
@@ -276,6 +276,21 @@ static int __init acpi_parse_hpet(struct acpi_table_header *table)
 		return -1;
 	}
 
+	if ( !hpet_tbl->address.address || !(hpet_tbl->address.address + 1) )
+	{
+		printk(KERN_WARNING PREFIX "Bad HPET address %#lx\n",
+		       hpet_tbl->address.address);
+		return -1;
+	}
+
+	/*
+	 * Hopefully someone might implement multiple HPET support in Xen.
+	 * Until then, warn the user if multiple HPET tables are found.
+	 */
+	if ( hpet_address )
+		printk(KERN_WARNING PREFIX
+		       "Xen only supports one HPET - Using latest table\n");
+
 	hpet_address = hpet_tbl->address.address;
 	hpet_blockid = hpet_tbl->sequence;
 	printk(KERN_INFO PREFIX "HPET id: %#x base: %#lx\n",
-- 
1.7.10.4