[PATCH 7/8] arm64/kexec: Add checks for KVM and EFI

[Geoff Levand]

Add runtime checks that fail the arm64 kexec syscall for situations that would
result in system instability do to problems in the KVM and EFI kernel support.
These checks should be removed when the KVM and EFI problems are fixed.

Signed-off-by: Geoff Levand <geoff at infradead.org>
---
 arch/arm64/kernel/machine_kexec.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index 775bcc3..5b62bd1f 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -16,6 +16,12 @@
 #include <asm/cacheflush.h>
 #include <asm/system_misc.h>
 
+/* TODO: Remove this include when KVM can support a kexc reboot. */
+#include <asm/virt.h>
+
+/* TODO: Remove this include when EFI can support a kexc reboot. */
+#include <linux/efi.h>
+
 /* Global variables for the relocate_kernel routine. */
 extern const unsigned char relocate_new_kernel[];
 extern const unsigned long relocate_new_kernel_size;
@@ -101,6 +107,22 @@ int machine_kexec_prepare(struct kimage *image)
 
 	kexec_image_info(image);
 
+	/* TODO: Remove this message when KVM can support a kexc reboot. */
+	if (IS_ENABLED(CONFIG_KVM) && is_hyp_mode_available()) {
+		pr_err("%s: Your kernel is configued with KVM support "
+			"(CONFIG_KVM=y) which currently does not allow for "
+			"kexec re-boot.\n", __func__);
+		return -ENOSYS;
+	}
+
+	/* TODO: Remove this message when EFI can support a kexc reboot. */
+	if (efi_enabled(EFI_BOOT)) {
+		pr_err("%s: Your kernel is using the Extensible Firmware "
+			"Interface (EFI) which currently does not allow for "
+			"kexec re-boot.\n", __func__);
+		return -ENOSYS;
+	}
+
 	return 0;
 }
 
-- 
1.9.1