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Diffstat (limited to 'arch/arm/kvm/interrupts.S')
| -rw-r--r-- | arch/arm/kvm/interrupts.S | 478 |
1 files changed, 478 insertions, 0 deletions
diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S new file mode 100644 index 00000000000..c5400d2e97c --- /dev/null +++ b/arch/arm/kvm/interrupts.S @@ -0,0 +1,478 @@ +/* + * 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 <linux/const.h> +#include <asm/unified.h> +#include <asm/page.h> +#include <asm/ptrace.h> +#include <asm/asm-offsets.h> +#include <asm/kvm_asm.h> +#include <asm/kvm_arm.h> +#include <asm/vfpmacros.h> +#include "interrupts_head.S" + + .text + +__kvm_hyp_code_start: + .globl __kvm_hyp_code_start + +/******************************************************************** + * Flush per-VMID TLBs + * + * void __kvm_tlb_flush_vmid(struct kvm *kvm); + * + * We rely on the hardware to broadcast the TLB invalidation to all CPUs + * inside the inner-shareable domain (which is the case for all v7 + * implementations). If we come across a non-IS SMP implementation, we'll + * have to use an IPI based mechanism. Until then, we stick to the simple + * hardware assisted version. + */ +ENTRY(__kvm_tlb_flush_vmid) + push {r2, r3} + + add r0, r0, #KVM_VTTBR + ldrd r2, r3, [r0] + mcrr p15, 6, r2, r3, c2 @ Write VTTBR + isb + mcr p15, 0, r0, c8, c3, 0 @ TLBIALLIS (rt ignored) + dsb + isb + mov r2, #0 + mov r3, #0 + mcrr p15, 6, r2, r3, c2 @ Back to VMID #0 + isb @ Not necessary if followed by eret + + pop {r2, r3} + bx lr +ENDPROC(__kvm_tlb_flush_vmid) + +/******************************************************************** + * Flush TLBs and instruction caches of all CPUs inside the inner-shareable + * domain, for all VMIDs + * + * void __kvm_flush_vm_context(void); + */ +ENTRY(__kvm_flush_vm_context) + mov r0, #0 @ rn parameter for c15 flushes is SBZ + + /* Invalidate NS Non-Hyp TLB Inner Shareable (TLBIALLNSNHIS) */ + mcr p15, 4, r0, c8, c3, 4 + /* Invalidate instruction caches Inner Shareable (ICIALLUIS) */ + mcr p15, 0, r0, c7, c1, 0 + dsb + isb @ Not necessary if followed by eret + + bx lr +ENDPROC(__kvm_flush_vm_context) + + +/******************************************************************** + * Hypervisor world-switch code + * + * + * int __kvm_vcpu_run(struct kvm_vcpu *vcpu) + */ +ENTRY(__kvm_vcpu_run) + @ Save the vcpu pointer + mcr p15, 4, vcpu, c13, c0, 2 @ HTPIDR + + save_host_regs + + @ Store hardware CP15 state and load guest state + read_cp15_state store_to_vcpu = 0 + write_cp15_state read_from_vcpu = 1 + + @ If the host kernel has not been configured with VFPv3 support, + @ then it is safer if we deny guests from using it as well. +#ifdef CONFIG_VFPv3 + @ Set FPEXC_EN so the guest doesn't trap floating point instructions + VFPFMRX r2, FPEXC @ VMRS + push {r2} + orr r2, r2, #FPEXC_EN + VFPFMXR FPEXC, r2 @ VMSR +#endif + + @ Configure Hyp-role + configure_hyp_role vmentry + + @ Trap coprocessor CRx accesses + set_hstr vmentry + set_hcptr vmentry, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11)) + set_hdcr vmentry + + @ Write configured ID register into MIDR alias + ldr r1, [vcpu, #VCPU_MIDR] + mcr p15, 4, r1, c0, c0, 0 + + @ Write guest view of MPIDR into VMPIDR + ldr r1, [vcpu, #CP15_OFFSET(c0_MPIDR)] + mcr p15, 4, r1, c0, c0, 5 + + @ Set up guest memory translation + ldr r1, [vcpu, #VCPU_KVM] + add r1, r1, #KVM_VTTBR + ldrd r2, r3, [r1] + mcrr p15, 6, r2, r3, c2 @ Write VTTBR + + @ We're all done, just restore the GPRs and go to the guest + restore_guest_regs + clrex @ Clear exclusive monitor + eret + +__kvm_vcpu_return: + /* + * return convention: + * guest r0, r1, r2 saved on the stack + * r0: vcpu pointer + * r1: exception code + */ + save_guest_regs + + @ Set VMID == 0 + mov r2, #0 + mov r3, #0 + mcrr p15, 6, r2, r3, c2 @ Write VTTBR + + @ Don't trap coprocessor accesses for host kernel + set_hstr vmexit + set_hdcr vmexit + set_hcptr vmexit, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11)) + +#ifdef CONFIG_VFPv3 + @ Save floating point registers we if let guest use them. + tst r2, #(HCPTR_TCP(10) | HCPTR_TCP(11)) + bne after_vfp_restore + + @ Switch VFP/NEON hardware state to the host's + add r7, vcpu, #VCPU_VFP_GUEST + store_vfp_state r7 + add r7, vcpu, #VCPU_VFP_HOST + ldr r7, [r7] + restore_vfp_state r7 + +after_vfp_restore: + @ Restore FPEXC_EN which we clobbered on entry + pop {r2} + VFPFMXR FPEXC, r2 +#endif + + @ Reset Hyp-role + configure_hyp_role vmexit + + @ Let host read hardware MIDR + mrc p15, 0, r2, c0, c0, 0 + mcr p15, 4, r2, c0, c0, 0 + + @ Back to hardware MPIDR + mrc p15, 0, r2, c0, c0, 5 + mcr p15, 4, r2, c0, c0, 5 + + @ Store guest CP15 state and restore host state + read_cp15_state store_to_vcpu = 1 + write_cp15_state read_from_vcpu = 0 + + restore_host_regs + clrex @ Clear exclusive monitor + mov r0, r1 @ Return the return code + mov r1, #0 @ Clear upper bits in return value + bx lr @ return to IOCTL + +/******************************************************************** + * Call function in Hyp mode + * + * + * u64 kvm_call_hyp(void *hypfn, ...); + * + * This is not really a variadic function in the classic C-way and care must + * be taken when calling this to ensure parameters are passed in registers + * only, since the stack will change between the caller and the callee. + * + * Call the function with the first argument containing a pointer to the + * function you wish to call in Hyp mode, and subsequent arguments will be + * passed as r0, r1, and r2 (a maximum of 3 arguments in addition to the + * function pointer can be passed). The function being called must be mapped + * in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c). Return values are + * passed in r0 and r1. + * + * The calling convention follows the standard AAPCS: + * r0 - r3: caller save + * r12: caller save + * rest: callee save + */ +ENTRY(kvm_call_hyp) + hvc #0 + bx lr + +/******************************************************************** + * 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 0x18 (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 0xc 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 and if + * so will push the necessary state (SPSR, lr_usr) on the Hyp stack. + * - 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). + */ + +/* Handle undef, svc, pabt, or dabt by crashing with a user notice */ +.macro bad_exception exception_code, panic_str + push {r0-r2} + mrrc p15, 6, r0, r1, c2 @ Read VTTBR + lsr r1, r1, #16 + ands r1, r1, #0xff + beq 99f + + load_vcpu @ Load VCPU pointer + .if \exception_code == ARM_EXCEPTION_DATA_ABORT + mrc p15, 4, r2, c5, c2, 0 @ HSR + mrc p15, 4, r1, c6, c0, 0 @ HDFAR + str r2, [vcpu, #VCPU_HSR] + str r1, [vcpu, #VCPU_HxFAR] + .endif + .if \exception_code == ARM_EXCEPTION_PREF_ABORT + mrc p15, 4, r2, c5, c2, 0 @ HSR + mrc p15, 4, r1, c6, c0, 2 @ HIFAR + str r2, [vcpu, #VCPU_HSR] + str r1, [vcpu, #VCPU_HxFAR] + .endif + mov r1, #\exception_code + b __kvm_vcpu_return + + @ We were in the host already. Let's craft a panic-ing return to SVC. +99: mrs r2, cpsr + bic r2, r2, #MODE_MASK + orr r2, r2, #SVC_MODE +THUMB( orr r2, r2, #PSR_T_BIT ) + msr spsr_cxsf, r2 + mrs r1, ELR_hyp + ldr r2, =BSYM(panic) + msr ELR_hyp, r2 + ldr r0, =\panic_str + eret +.endm + + .text + + .align 5 +__kvm_hyp_vector: + .globl __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 + + .align +hyp_reset: + b hyp_reset + + .align +hyp_undef: + bad_exception ARM_EXCEPTION_UNDEFINED, und_die_str + + .align +hyp_svc: + bad_exception ARM_EXCEPTION_HVC, svc_die_str + + .align +hyp_pabt: + bad_exception ARM_EXCEPTION_PREF_ABORT, pabt_die_str + + .align +hyp_dabt: + bad_exception ARM_EXCEPTION_DATA_ABORT, dabt_die_str + + .align +hyp_hvc: + /* + * Getting here is either becuase of a trap from a guest or from calling + * HVC from the host kernel, which means "switch to Hyp mode". + */ + push {r0, r1, r2} + + @ Check syndrome register + mrc p15, 4, r1, c5, c2, 0 @ HSR + lsr r0, r1, #HSR_EC_SHIFT +#ifdef CONFIG_VFPv3 + cmp r0, #HSR_EC_CP_0_13 + beq switch_to_guest_vfp +#endif + 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 + +host_switch_to_hyp: + pop {r0, r1, r2} + + push {lr} + mrs lr, SPSR + 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} + msr SPSR_csxf, lr + pop {lr} + eret + +guest_trap: + load_vcpu @ Load VCPU pointer to r0 + str r1, [vcpu, #VCPU_HSR] + + @ Check if we need the fault information + lsr r1, r1, #HSR_EC_SHIFT + cmp r1, #HSR_EC_IABT + mrceq p15, 4, r2, c6, c0, 2 @ HIFAR + beq 2f + cmp r1, #HSR_EC_DABT + bne 1f + mrc p15, 4, r2, c6, c0, 0 @ HDFAR + +2: str r2, [vcpu, #VCPU_HxFAR] + + /* + * B3.13.5 Reporting exceptions taken to the Non-secure PL2 mode: + * + * Abort on the stage 2 translation for a memory access from a + * Non-secure PL1 or PL0 mode: + * + * For any Access flag fault or Translation fault, and also for any + * Permission fault on the stage 2 translation of a memory access + * made as part of a translation table walk for a stage 1 translation, + * the HPFAR holds the IPA that caused the fault. Otherwise, the HPFAR + * is UNKNOWN. + */ + + /* Check for permission fault, and S1PTW */ + mrc p15, 4, r1, c5, c2, 0 @ HSR + and r0, r1, #HSR_FSC_TYPE + cmp r0, #FSC_PERM + tsteq r1, #(1 << 7) @ S1PTW + mrcne p15, 4, r2, c6, c0, 4 @ HPFAR + bne 3f + + /* Resolve IPA using the xFAR */ + mcr p15, 0, r2, c7, c8, 0 @ ATS1CPR + isb + mrrc p15, 0, r0, r1, c7 @ PAR + tst r0, #1 + bne 4f @ Failed translation + ubfx r2, r0, #12, #20 + lsl r2, r2, #4 + orr r2, r2, r1, lsl #24 + +3: load_vcpu @ Load VCPU pointer to r0 + str r2, [r0, #VCPU_HPFAR] + +1: mov r1, #ARM_EXCEPTION_HVC + b __kvm_vcpu_return + +4: pop {r0, r1, r2} @ Failed translation, return to guest + eret + +/* + * If VFPv3 support is not available, then we will not switch the VFP + * registers; however cp10 and cp11 accesses will still trap and fallback + * to the regular coprocessor emulation code, which currently will + * inject an undefined exception to the guest. + */ +#ifdef CONFIG_VFPv3 +switch_to_guest_vfp: + load_vcpu @ Load VCPU pointer to r0 + push {r3-r7} + + @ NEON/VFP used. Turn on VFP access. + set_hcptr vmexit, (HCPTR_TCP(10) | HCPTR_TCP(11)) + + @ Switch VFP/NEON hardware state to the guest's + add r7, r0, #VCPU_VFP_HOST + ldr r7, [r7] + store_vfp_state r7 + add r7, r0, #VCPU_VFP_GUEST + restore_vfp_state r7 + + pop {r3-r7} + pop {r0-r2} + eret +#endif + + .align +hyp_irq: + push {r0, r1, r2} + mov r1, #ARM_EXCEPTION_IRQ + load_vcpu @ Load VCPU pointer to r0 + b __kvm_vcpu_return + + .align +hyp_fiq: + b hyp_fiq + + .ltorg + +__kvm_hyp_code_end: + .globl __kvm_hyp_code_end + + .section ".rodata" + +und_die_str: + .ascii "unexpected undefined exception in Hyp mode at: %#08x" +pabt_die_str: + .ascii "unexpected prefetch abort in Hyp mode at: %#08x" +dabt_die_str: + .ascii "unexpected data abort in Hyp mode at: %#08x" +svc_die_str: + .ascii "unexpected HVC/SVC trap in Hyp mode at: %#08x" |