1 files changed, 215 insertions, 0 deletions
diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
new file mode 100644
index 000000000..f3aa7738b
--- /dev/null
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -0,0 +1,215 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2015 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ */
+
+#include <linux/linkage.h>
+
+#include <asm/alternative.h>
+#include <asm/assembler.h>
+#include <asm/fpsimdmacros.h>
+#include <asm/kvm.h>
+#include <asm/kvm_arm.h>
+#include <asm/kvm_asm.h>
+#include <asm/kvm_mmu.h>
+#include <asm/kvm_mte.h>
+#include <asm/kvm_ptrauth.h>
+
+	.text
+
+/*
+ * u64 __guest_enter(struct kvm_vcpu *vcpu);
+ */
+SYM_FUNC_START(__guest_enter)
+	// x0: vcpu
+	// x1-x17: clobbered by macros
+	// x29: guest context
+
+	adr_this_cpu x1, kvm_hyp_ctxt, x2
+
+	// Store the hyp regs
+	save_callee_saved_regs x1
+
+	// Save hyp's sp_el0
+	save_sp_el0	x1, x2
+
+	// Now the hyp state is stored if we have a pending RAS SError it must
+	// affect the host or hyp. If any asynchronous exception is pending we
+	// defer the guest entry. The DSB isn't necessary before v8.2 as any
+	// SError would be fatal.
+alternative_if ARM64_HAS_RAS_EXTN
+	dsb	nshst
+	isb
+alternative_else_nop_endif
+	mrs	x1, isr_el1
+	cbz	x1,  1f
+	mov	x0, #ARM_EXCEPTION_IRQ
+	ret
+
+1:
+	set_loaded_vcpu x0, x1, x2
+
+	add	x29, x0, #VCPU_CONTEXT
+
+	// mte_switch_to_guest(g_ctxt, h_ctxt, tmp1)
+	mte_switch_to_guest x29, x1, x2
+
+	// Macro ptrauth_switch_to_guest format:
+	// 	ptrauth_switch_to_guest(guest cxt, tmp1, tmp2, tmp3)
+	// The below macro to restore guest keys is not implemented in C code
+	// as it may cause Pointer Authentication key signing mismatch errors
+	// when this feature is enabled for kernel code.
+	ptrauth_switch_to_guest x29, x0, x1, x2
+
+	// Restore the guest's sp_el0
+	restore_sp_el0 x29, x0
+
+	// Restore guest regs x0-x17
+	ldp	x0, x1,   [x29, #CPU_XREG_OFFSET(0)]
+	ldp	x2, x3,   [x29, #CPU_XREG_OFFSET(2)]
+	ldp	x4, x5,   [x29, #CPU_XREG_OFFSET(4)]
+	ldp	x6, x7,   [x29, #CPU_XREG_OFFSET(6)]
+	ldp	x8, x9,   [x29, #CPU_XREG_OFFSET(8)]
+	ldp	x10, x11, [x29, #CPU_XREG_OFFSET(10)]
+	ldp	x12, x13, [x29, #CPU_XREG_OFFSET(12)]
+	ldp	x14, x15, [x29, #CPU_XREG_OFFSET(14)]
+	ldp	x16, x17, [x29, #CPU_XREG_OFFSET(16)]
+
+	// Restore guest regs x18-x29, lr
+	restore_callee_saved_regs x29
+
+	// Do not touch any register after this!
+	eret
+	sb
+
+SYM_INNER_LABEL(__guest_exit_panic, SYM_L_GLOBAL)
+	// x2-x29,lr: vcpu regs
+	// vcpu x0-x1 on the stack
+
+	// If the hyp context is loaded, go straight to hyp_panic
+	get_loaded_vcpu x0, x1
+	cbnz	x0, 1f
+	b	hyp_panic
+
+1:
+	// The hyp context is saved so make sure it is restored to allow
+	// hyp_panic to run at hyp and, subsequently, panic to run in the host.
+	// This makes use of __guest_exit to avoid duplication but sets the
+	// return address to tail call into hyp_panic. As a side effect, the
+	// current state is saved to the guest context but it will only be
+	// accurate if the guest had been completely restored.
+	adr_this_cpu x0, kvm_hyp_ctxt, x1
+	adr_l	x1, hyp_panic
+	str	x1, [x0, #CPU_XREG_OFFSET(30)]
+
+	get_vcpu_ptr	x1, x0
+
+SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
+	// x0: return code
+	// x1: vcpu
+	// x2-x29,lr: vcpu regs
+	// vcpu x0-x1 on the stack
+
+	add	x1, x1, #VCPU_CONTEXT
+
+	ALTERNATIVE(nop, SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
+
+	// Store the guest regs x2 and x3
+	stp	x2, x3,   [x1, #CPU_XREG_OFFSET(2)]
+
+	// Retrieve the guest regs x0-x1 from the stack
+	ldp	x2, x3, [sp], #16	// x0, x1
+
+	// Store the guest regs x0-x1 and x4-x17
+	stp	x2, x3,   [x1, #CPU_XREG_OFFSET(0)]
+	stp	x4, x5,   [x1, #CPU_XREG_OFFSET(4)]
+	stp	x6, x7,   [x1, #CPU_XREG_OFFSET(6)]
+	stp	x8, x9,   [x1, #CPU_XREG_OFFSET(8)]
+	stp	x10, x11, [x1, #CPU_XREG_OFFSET(10)]
+	stp	x12, x13, [x1, #CPU_XREG_OFFSET(12)]
+	stp	x14, x15, [x1, #CPU_XREG_OFFSET(14)]
+	stp	x16, x17, [x1, #CPU_XREG_OFFSET(16)]
+
+	// Store the guest regs x18-x29, lr
+	save_callee_saved_regs x1
+
+	// Store the guest's sp_el0
+	save_sp_el0	x1, x2
+
+	adr_this_cpu x2, kvm_hyp_ctxt, x3
+
+	// Macro ptrauth_switch_to_hyp format:
+	// 	ptrauth_switch_to_hyp(guest cxt, host cxt, tmp1, tmp2, tmp3)
+	// The below macro to save/restore keys is not implemented in C code
+	// as it may cause Pointer Authentication key signing mismatch errors
+	// when this feature is enabled for kernel code.
+	ptrauth_switch_to_hyp x1, x2, x3, x4, x5
+
+	// mte_switch_to_hyp(g_ctxt, h_ctxt, reg1)
+	mte_switch_to_hyp x1, x2, x3
+
+	// Restore hyp's sp_el0
+	restore_sp_el0 x2, x3
+
+	// Now restore the hyp regs
+	restore_callee_saved_regs x2
+
+	set_loaded_vcpu xzr, x2, x3
+
+alternative_if ARM64_HAS_RAS_EXTN
+	// If we have the RAS extensions we can consume a pending error
+	// without an unmask-SError and isb. The ESB-instruction consumed any
+	// pending guest error when we took the exception from the guest.
+	mrs_s	x2, SYS_DISR_EL1
+	str	x2, [x1, #(VCPU_FAULT_DISR - VCPU_CONTEXT)]
+	cbz	x2, 1f
+	msr_s	SYS_DISR_EL1, xzr
+	orr	x0, x0, #(1<<ARM_EXIT_WITH_SERROR_BIT)
+1:	ret
+alternative_else
+	dsb	sy		// Synchronize against in-flight ld/st
+	isb			// Prevent an early read of side-effect free ISR
+	mrs	x2, isr_el1
+	tbnz	x2, #ISR_EL1_A_SHIFT, 2f
+	ret
+	nop
+2:
+alternative_endif
+	// We know we have a pending asynchronous abort, now is the
+	// time to flush it out. From your VAXorcist book, page 666:
+	// "Threaten me not, oh Evil one!  For I speak with
+	// the power of DEC, and I command thee to show thyself!"
+	mrs	x2, elr_el2
+	mrs	x3, esr_el2
+	mrs	x4, spsr_el2
+	mov	x5, x0
+
+	msr	daifclr, #4	// Unmask aborts
+
+	// This is our single instruction exception window. A pending
+	// SError is guaranteed to occur at the earliest when we unmask
+	// it, and at the latest just after the ISB.
+abort_guest_exit_start:
+
+	isb
+
+abort_guest_exit_end:
+
+	msr	daifset, #4	// Mask aborts
+	ret
+
+	_kvm_extable	abort_guest_exit_start, 9997f
+	_kvm_extable	abort_guest_exit_end, 9997f
+9997:
+	msr	daifset, #4	// Mask aborts
+	mov	x0, #(1 << ARM_EXIT_WITH_SERROR_BIT)
+
+	// restore the EL1 exception context so that we can report some
+	// information. Merge the exception code with the SError pending bit.
+	msr	elr_el2, x2
+	msr	esr_el2, x3
+	msr	spsr_el2, x4
+	orr	x0, x0, x5
+1:	ret
+SYM_FUNC_END(__guest_enter)