arm64: add hypervisor stub
If booted in EL2, install an dummy hypervisor whose only purpose
is to be replaced by a full fledged one.
A minimal API allows to:
- obtain the current HYP vectors (__hyp_get_vectors)
- set new HYP vectors (__hyp_set_vectors)
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
new file mode 100644
index 0000000..0959611
--- /dev/null
+++ b/arch/arm64/kernel/hyp-stub.S
@@ -0,0 +1,109 @@
+/*
+ * Hypervisor stub
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+
+#include <asm/assembler.h>
+#include <asm/ptrace.h>
+#include <asm/virt.h>
+
+ .text
+ .align 11
+
+ENTRY(__hyp_stub_vectors)
+ ventry el2_sync_invalid // Synchronous EL2t
+ ventry el2_irq_invalid // IRQ EL2t
+ ventry el2_fiq_invalid // FIQ EL2t
+ ventry el2_error_invalid // Error EL2t
+
+ ventry el2_sync_invalid // Synchronous EL2h
+ ventry el2_irq_invalid // IRQ EL2h
+ ventry el2_fiq_invalid // FIQ EL2h
+ ventry el2_error_invalid // Error EL2h
+
+ ventry el1_sync // Synchronous 64-bit EL1
+ ventry el1_irq_invalid // IRQ 64-bit EL1
+ ventry el1_fiq_invalid // FIQ 64-bit EL1
+ ventry el1_error_invalid // Error 64-bit EL1
+
+ ventry el1_sync_invalid // Synchronous 32-bit EL1
+ ventry el1_irq_invalid // IRQ 32-bit EL1
+ ventry el1_fiq_invalid // FIQ 32-bit EL1
+ ventry el1_error_invalid // Error 32-bit EL1
+ENDPROC(__hyp_stub_vectors)
+
+ .align 11
+
+el1_sync:
+ mrs x1, esr_el2
+ lsr x1, x1, #26
+ cmp x1, #0x16
+ b.ne 2f // Not an HVC trap
+ cbz x0, 1f
+ msr vbar_el2, x0 // Set vbar_el2
+ b 2f
+1: mrs x0, vbar_el2 // Return vbar_el2
+2: eret
+ENDPROC(el1_sync)
+
+.macro invalid_vector label
+\label:
+ b \label
+ENDPROC(\label)
+.endm
+
+ invalid_vector el2_sync_invalid
+ invalid_vector el2_irq_invalid
+ invalid_vector el2_fiq_invalid
+ invalid_vector el2_error_invalid
+ invalid_vector el1_sync_invalid
+ invalid_vector el1_irq_invalid
+ invalid_vector el1_fiq_invalid
+ invalid_vector el1_error_invalid
+
+/*
+ * __hyp_set_vectors: Call this after boot to set the initial hypervisor
+ * vectors as part of hypervisor installation. On an SMP system, this should
+ * be called on each CPU.
+ *
+ * x0 must be the physical address of the new vector table, and must be
+ * 2KB aligned.
+ *
+ * Before calling this, you must check that the stub hypervisor is installed
+ * everywhere, by waiting for any secondary CPUs to be brought up and then
+ * checking that is_hyp_mode_available() is true.
+ *
+ * If not, there is a pre-existing hypervisor, some CPUs failed to boot, or
+ * something else went wrong... in such cases, trying to install a new
+ * hypervisor is unlikely to work as desired.
+ *
+ * When you call into your shiny new hypervisor, sp_el2 will contain junk,
+ * so you will need to set that to something sensible at the new hypervisor's
+ * initialisation entry point.
+ */
+
+ENTRY(__hyp_get_vectors)
+ mov x0, xzr
+ // fall through
+ENTRY(__hyp_set_vectors)
+ hvc #0
+ ret
+ENDPROC(__hyp_get_vectors)
+ENDPROC(__hyp_set_vectors)