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Diffstat (limited to 'arch/arm/kvm/hyp/hyp-entry.S')
| -rw-r--r-- | arch/arm/kvm/hyp/hyp-entry.S | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/arch/arm/kvm/hyp/hyp-entry.S b/arch/arm/kvm/hyp/hyp-entry.S new file mode 100644 index 000000000..78091383a --- /dev/null +++ b/arch/arm/kvm/hyp/hyp-entry.S @@ -0,0 +1,169 @@ +/* + * Copyright (C) 2012 - Virtual Open Systems and Columbia University + * Author: Christoffer Dall <c.dall@virtualopensystems.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, write to the Free Software + * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + */ + +#include <linux/linkage.h> +#include <asm/kvm_arm.h> +#include <asm/kvm_asm.h> + + .arch_extension virt + + .text + .pushsection .hyp.text, "ax" + +.macro load_vcpu reg + mrc p15, 4, \reg, c13, c0, 2 @ HTPIDR +.endm + +/******************************************************************** + * Hypervisor exception vector and handlers + * + * + * The KVM/ARM Hypervisor ABI is defined as follows: + * + * Entry to Hyp mode from the host kernel will happen _only_ when an HVC + * instruction is issued since all traps are disabled when running the host + * kernel as per the Hyp-mode initialization at boot time. + * + * HVC instructions cause a trap to the vector page + offset 0x14 (see hyp_hvc + * below) when the HVC instruction is called from SVC mode (i.e. a guest or the + * host kernel) and they cause a trap to the vector page + offset 0x8 when HVC + * instructions are called from within Hyp-mode. + * + * Hyp-ABI: Calling HYP-mode functions from host (in SVC mode): + * Switching to Hyp mode is done through a simple HVC #0 instruction. The + * exception vector code will check that the HVC comes from VMID==0. + * - r0 contains a pointer to a HYP function + * - r1, r2, and r3 contain arguments to the above function. + * - The HYP function will be called with its arguments in r0, r1 and r2. + * On HYP function return, we return directly to SVC. + * + * Note that the above is used to execute code in Hyp-mode from a host-kernel + * point of view, and is a different concept from performing a world-switch and + * executing guest code SVC mode (with a VMID != 0). + */ + + .align 5 +__kvm_hyp_vector: + .global __kvm_hyp_vector + + @ Hyp-mode exception vector + W(b) hyp_reset + W(b) hyp_undef + W(b) hyp_svc + W(b) hyp_pabt + W(b) hyp_dabt + W(b) hyp_hvc + W(b) hyp_irq + W(b) hyp_fiq + +.macro invalid_vector label, cause + .align +\label: mov r0, #\cause + b __hyp_panic +.endm + + invalid_vector hyp_reset ARM_EXCEPTION_RESET + invalid_vector hyp_undef ARM_EXCEPTION_UNDEFINED + invalid_vector hyp_svc ARM_EXCEPTION_SOFTWARE + invalid_vector hyp_pabt ARM_EXCEPTION_PREF_ABORT + invalid_vector hyp_dabt ARM_EXCEPTION_DATA_ABORT + invalid_vector hyp_fiq ARM_EXCEPTION_FIQ + +ENTRY(__hyp_do_panic) + mrs lr, cpsr + bic lr, lr, #MODE_MASK + orr lr, lr, #SVC_MODE +THUMB( orr lr, lr, #PSR_T_BIT ) + msr spsr_cxsf, lr + ldr lr, =panic + msr ELR_hyp, lr + ldr lr, =kvm_call_hyp + clrex + eret +ENDPROC(__hyp_do_panic) + +hyp_hvc: + /* + * Getting here is either because of a trap from a guest, + * or from executing HVC from the host kernel, which means + * "do something in Hyp mode". + */ + push {r0, r1, r2} + + @ Check syndrome register + mrc p15, 4, r1, c5, c2, 0 @ HSR + lsr r0, r1, #HSR_EC_SHIFT + cmp r0, #HSR_EC_HVC + bne guest_trap @ Not HVC instr. + + /* + * Let's check if the HVC came from VMID 0 and allow simple + * switch to Hyp mode + */ + mrrc p15, 6, r0, r2, c2 + lsr r2, r2, #16 + and r2, r2, #0xff + cmp r2, #0 + bne guest_trap @ Guest called HVC + + /* + * Getting here means host called HVC, we shift parameters and branch + * to Hyp function. + */ + pop {r0, r1, r2} + + /* Check for __hyp_get_vectors */ + cmp r0, #-1 + mrceq p15, 4, r0, c12, c0, 0 @ get HVBAR + beq 1f + + push {lr} + + mov lr, r0 + mov r0, r1 + mov r1, r2 + mov r2, r3 + +THUMB( orr lr, #1) + blx lr @ Call the HYP function + + pop {lr} +1: eret + +guest_trap: + load_vcpu r0 @ Load VCPU pointer to r0 + +#ifdef CONFIG_VFPv3 + @ Check for a VFP access + lsr r1, r1, #HSR_EC_SHIFT + cmp r1, #HSR_EC_CP_0_13 + beq __vfp_guest_restore +#endif + + mov r1, #ARM_EXCEPTION_HVC + b __guest_exit + +hyp_irq: + push {r0, r1, r2} + mov r1, #ARM_EXCEPTION_IRQ + load_vcpu r0 @ Load VCPU pointer to r0 + b __guest_exit + + .ltorg + + .popsection |