Staging: unisys: detect s-Par firmware

This patch adds support for detection of s-Par firmware by checking for
the hypervisor bit in the CPU capabilities, and then querying the hypervisor
ID cpuid leaf.

This functionality will be used by the unisys drivers to determine if
they are being loaded on an s-Par platform and refuse to load if no
s-Par firmware is present.

This fixes a problem reported from upstream where a panic occurs if the
unisys drivers are loaded on a non s-Par system.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Ken Cox <jkc@redhat.com>
Tested by: Ken Cox <jkc@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/channels/chanstub.c

@@ -25,11 +25,14 @@
 
 #include "channel.h"
 #include "chanstub.h"
+#include "timskmodutils.h"
 #include "version.h"
 
 static __init int
 channel_mod_init(void)
 {
+	if (!unisys_spar_platform)
+		return -ENODEV;
 	return 0;
 }
 

drivers/staging/unisys/include/timskmodutils.h

@@ -72,4 +72,6 @@ char *cyclesToSomethingsPerSecond(u64 cycles, u64 cyclesPerSecond,
 struct seq_file *visor_seq_file_new_buffer(void *buf, size_t buf_size);
 void visor_seq_file_done_buffer(struct seq_file *m);
 
+extern int unisys_spar_platform;
+
 #endif

drivers/staging/unisys/uislib/uislib.c

@@ -2277,6 +2277,9 @@ static int __init
 uislib_mod_init(void)
 {
 
+	if (!unisys_spar_platform)
+		return -ENODEV;
+
 	LOGINF("MONITORAPIS");
 
 	LOGINF("sizeof(struct uiscmdrsp):%lu bytes\n",

drivers/staging/unisys/virthba/virthba.c

@@ -1699,6 +1699,9 @@ virthba_mod_init(void)
 	int error;
 	int i;
 
+	if (!unisys_spar_platform)
+		return -ENODEV;
+
 	LOGINF("Entering virthba_mod_init...\n");
 
 	POSTCODE_LINUX_2(VHBA_CREATE_ENTRY_PC, POSTCODE_SEVERITY_INFO);

drivers/staging/unisys/virtpci/virtpci.c

@@ -39,6 +39,7 @@
 #include <linux/version.h>
 #include "version.h"
 #include "guestlinuxdebug.h"
+#include "timskmodutils.h"
 
 struct driver_private {
 	struct kobject kobj;
@@ -1687,6 +1688,9 @@ static int __init virtpci_mod_init(void)
 	int ret;
 
 
+	if (!unisys_spar_platform)
+		return -ENODEV;
+
 	LOGINF("Module build: Date:%s Time:%s...\n", __DATE__, __TIME__);
 
 	POSTCODE_LINUX_2(VPCI_CREATE_ENTRY_PC, POSTCODE_SEVERITY_INFO);

drivers/staging/unisys/visorchannel/visorchannel_main.c

@@ -29,6 +29,9 @@
 static int __init
 visorchannel_init(void)
 {
+	if (!unisys_spar_platform)
+		return -ENODEV;
+
 	INFODRV("driver version %s loaded", VERSION);
 	return 0;
 }

drivers/staging/unisys/visorchipset/visorchipset_main.c

@@ -2699,6 +2699,9 @@ visorchipset_init(void)
 	struct proc_dir_entry *toolaction_file;
 	struct proc_dir_entry *bootToTool_file;
 
+	if (!unisys_spar_platform)
+		return -ENODEV;
+
 	LOGINF("chipset driver version %s loaded", VERSION);
 	/* process module options */
 	POSTCODE_LINUX_2(DRIVER_ENTRY_PC, POSTCODE_SEVERITY_INFO);

drivers/staging/unisys/visorutil/visorkmodutils.c

@@ -20,6 +20,22 @@
 
 #define MYDRVNAME "timskmodutils"
 
+/* s-Par uses the Intel processor's VT-X features to separate groups of
+ * processors into partitions. The firmware sets the hypervisor bit and
+ * reports an ID in the HV capabilities leaf so that the partition's OS
+ * knows s-Par is present and managing the processors.
+ */
+
+#define UNISYS_SPAR_LEAF_ID 0x40000000
+
+/* The s-Par leaf ID returns "UnisysSpar64" encoded across ebx, ecx, edx */
+#define UNISYS_SPAR_ID_EBX 0x73696e55
+#define UNISYS_SPAR_ID_ECX 0x70537379
+#define UNISYS_SPAR_ID_EDX 0x34367261
+
+int unisys_spar_platform;
+EXPORT_SYMBOL_GPL(unisys_spar_platform);
+
 /** Callers to interfaces that set __GFP_NORETRY flag below
  *  must check for a NULL (error) result as we are telling the
  *  kernel interface that it is okay to fail.
@@ -69,3 +85,41 @@ void visor_seq_file_done_buffer(struct seq_file *m)
 	kfree(m);
 }
 EXPORT_SYMBOL_GPL(visor_seq_file_done_buffer);
+
+static __init uint32_t
+visorutil_spar_detect(void)
+{
+	unsigned int eax, ebx, ecx, edx;
+
+	if (cpu_has_hypervisor) {
+		/* check the ID */
+		cpuid(UNISYS_SPAR_LEAF_ID, &eax, &ebx, &ecx, &edx);
+		return  (ebx == UNISYS_SPAR_ID_EBX) &&
+			(ecx == UNISYS_SPAR_ID_ECX) &&
+			(edx == UNISYS_SPAR_ID_EDX);
+	} else
+		return 0;
+
+}
+
+
+
+
+static __init int
+visorutil_mod_init(void)
+{
+	if (visorutil_spar_detect()) {
+		unisys_spar_platform = TRUE;
+		return 0;
+	} else
+		return -ENODEV;
+}
+
+static __exit void
+visorutil_mod_exit(void)
+{
+}
+
+module_init(visorutil_mod_init);
+module_exit(visorutil_mod_exit);
+