[RFC PATCH v1] powerpc/prom_init: disable XIVE in Secure VM.

[Ram Pai <linuxram@us.ibm.com>]

XIVE is not correctly enabled for Secure VM in the KVM Hypervisor yet.

Hence Secure VM, must always default to XICS interrupt controller.

If XIVE is requested through kernel command line option "xive=on",
override and turn it off.

If XIVE is the only supported platform interrupt controller; specified
through qemu option "ic-mode=xive", simply abort. Otherwise default to
XICS.

Cc: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc: Michael Anderson <andmike@linux.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Greg Kurz <groug@kaod.org>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
 arch/powerpc/kernel/prom_init.c | 43 ++++++++++++++++++++++++++++-------------
 1 file changed, 30 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 5773453..dd96c82 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -805,6 +805,18 @@ static void __init early_cmdline_parse(void)
 #endif
 	}
 
+#ifdef CONFIG_PPC_SVM
+	opt = prom_strstr(prom_cmd_line, "svm=");
+	if (opt) {
+		bool val;
+
+		opt += sizeof("svm=") - 1;
+		if (!prom_strtobool(opt, &val))
+			prom_svm_enable = val;
+		prom_printf("svm =%d\n", prom_svm_enable);
+	}
+#endif /* CONFIG_PPC_SVM */
+
 #ifdef CONFIG_PPC_PSERIES
 	prom_radix_disable = !IS_ENABLED(CONFIG_PPC_RADIX_MMU_DEFAULT);
 	opt = prom_strstr(prom_cmd_line, "disable_radix");
@@ -823,23 +835,22 @@ static void __init early_cmdline_parse(void)
 	if (prom_radix_disable)
 		prom_debug("Radix disabled from cmdline\n");
 
-	opt = prom_strstr(prom_cmd_line, "xive=off");
-	if (opt) {
+#ifdef CONFIG_PPC_SVM
+	if (prom_svm_enable) {
 		prom_xive_disable = true;
-		prom_debug("XIVE disabled from cmdline\n");
+		prom_debug("XIVE disabled in Secure VM\n");
 	}
-#endif /* CONFIG_PPC_PSERIES */
-
-#ifdef CONFIG_PPC_SVM
-	opt = prom_strstr(prom_cmd_line, "svm=");
-	if (opt) {
-		bool val;
+#endif /* CONFIG_PPC_SVM */
 
-		opt += sizeof("svm=") - 1;
-		if (!prom_strtobool(opt, &val))
-			prom_svm_enable = val;
+	if (!prom_xive_disable) {
+		opt = prom_strstr(prom_cmd_line, "xive=off");
+		if (opt) {
+			prom_xive_disable = true;
+			prom_debug("XIVE disabled from cmdline\n");
+		}
 	}
-#endif /* CONFIG_PPC_SVM */
+
+#endif /* CONFIG_PPC_PSERIES */
 }
 
 #ifdef CONFIG_PPC_PSERIES
@@ -1251,6 +1262,12 @@ static void __init prom_parse_xive_model(u8 val,
 		break;
 	case OV5_FEAT(OV5_XIVE_EXPLOIT): /* Only Exploitation mode */
 		prom_debug("XIVE - exploitation mode supported\n");
+
+#ifdef CONFIG_PPC_SVM
+		if (prom_svm_enable)
+			prom_panic("WARNING: xive unsupported in Secure VM\n");
+#endif /* CONFIG_PPC_SVM */
+
 		if (prom_xive_disable) {
 			/*
 			 * If we __have__ to do XIVE, we're better off ignoring
-- 
1.8.3.1