The HYP mode world switch in all its glory. Implements save/restore of host/guest registers, EL2 trapping, IPA resolution, and additional services (tlb invalidation). Reviewed-by: Christopher Covington <cov@xxxxxxxxxxxxxx> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> --- arch/arm64/kernel/asm-offsets.c | 34 +++ arch/arm64/kvm/hyp.S | 603 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 637 insertions(+) create mode 100644 arch/arm64/kvm/hyp.S diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index a2a4d81..666e231 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -21,6 +21,7 @@ #include <linux/sched.h> #include <linux/mm.h> #include <linux/dma-mapping.h> +#include <linux/kvm_host.h> #include <asm/thread_info.h> #include <asm/memory.h> #include <asm/cputable.h> @@ -104,5 +105,38 @@ int main(void) BLANK(); DEFINE(TZ_MINWEST, offsetof(struct timezone, tz_minuteswest)); DEFINE(TZ_DSTTIME, offsetof(struct timezone, tz_dsttime)); + BLANK(); +#ifdef CONFIG_KVM_ARM_HOST + DEFINE(VCPU_CONTEXT, offsetof(struct kvm_vcpu, arch.ctxt)); + DEFINE(CPU_GP_REGS, offsetof(struct kvm_cpu_context, gp_regs)); + DEFINE(CPU_USER_PT_REGS, offsetof(struct kvm_regs, regs)); + DEFINE(CPU_FP_REGS, offsetof(struct kvm_regs, fp_regs)); + DEFINE(CPU_SP_EL1, offsetof(struct kvm_regs, sp_el1)); + DEFINE(CPU_ELR_EL1, offsetof(struct kvm_regs, elr_el1)); + DEFINE(CPU_SPSR, offsetof(struct kvm_regs, spsr)); + DEFINE(CPU_SYSREGS, offsetof(struct kvm_cpu_context, sys_regs)); + DEFINE(VCPU_ESR_EL2, offsetof(struct kvm_vcpu, arch.fault.esr_el2)); + DEFINE(VCPU_FAR_EL2, offsetof(struct kvm_vcpu, arch.fault.far_el2)); + DEFINE(VCPU_HPFAR_EL2, offsetof(struct kvm_vcpu, arch.fault.hpfar_el2)); + DEFINE(VCPU_HCR_EL2, offsetof(struct kvm_vcpu, arch.hcr_el2)); + DEFINE(VCPU_IRQ_LINES, offsetof(struct kvm_vcpu, arch.irq_lines)); + DEFINE(VCPU_HOST_CONTEXT, offsetof(struct kvm_vcpu, arch.host_cpu_context)); + DEFINE(VCPU_TIMER_CNTV_CTL, offsetof(struct kvm_vcpu, arch.timer_cpu.cntv_ctl)); + DEFINE(VCPU_TIMER_CNTV_CVAL, offsetof(struct kvm_vcpu, arch.timer_cpu.cntv_cval)); + DEFINE(KVM_TIMER_CNTVOFF, offsetof(struct kvm, arch.timer.cntvoff)); + DEFINE(KVM_TIMER_ENABLED, offsetof(struct kvm, arch.timer.enabled)); + DEFINE(VCPU_KVM, offsetof(struct kvm_vcpu, kvm)); + DEFINE(VCPU_VGIC_CPU, offsetof(struct kvm_vcpu, arch.vgic_cpu)); + DEFINE(VGIC_CPU_HCR, offsetof(struct vgic_cpu, vgic_hcr)); + DEFINE(VGIC_CPU_VMCR, offsetof(struct vgic_cpu, vgic_vmcr)); + DEFINE(VGIC_CPU_MISR, offsetof(struct vgic_cpu, vgic_misr)); + DEFINE(VGIC_CPU_EISR, offsetof(struct vgic_cpu, vgic_eisr)); + DEFINE(VGIC_CPU_ELRSR, offsetof(struct vgic_cpu, vgic_elrsr)); + DEFINE(VGIC_CPU_APR, offsetof(struct vgic_cpu, vgic_apr)); + DEFINE(VGIC_CPU_LR, offsetof(struct vgic_cpu, vgic_lr)); + DEFINE(VGIC_CPU_NR_LR, offsetof(struct vgic_cpu, nr_lr)); + DEFINE(KVM_VTTBR, offsetof(struct kvm, arch.vttbr)); + DEFINE(KVM_VGIC_VCTRL, offsetof(struct kvm, arch.vgic.vctrl_base)); +#endif return 0; } diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S new file mode 100644 index 0000000..e6884d3 --- /dev/null +++ b/arch/arm64/kvm/hyp.S @@ -0,0 +1,603 @@ +/* + * Copyright (C) 2012,2013 - ARM Ltd + * Author: Marc Zyngier <marc.zyngier@xxxxxxx> + * + * 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/linkage.h> +#include <linux/irqchip/arm-gic.h> + +#include <asm/assembler.h> +#include <asm/memory.h> +#include <asm/asm-offsets.h> +#include <asm/fpsimdmacros.h> +#include <asm/kvm.h> +#include <asm/kvm_asm.h> +#include <asm/kvm_arm.h> +#include <asm/kvm_mmu.h> + +#define CPU_GP_REG_OFFSET(x) (CPU_GP_REGS + x) +#define CPU_XREG_OFFSET(x) CPU_GP_REG_OFFSET(CPU_USER_PT_REGS + 8*x) +#define CPU_SPSR_OFFSET(x) CPU_GP_REG_OFFSET(CPU_SPSR + 8*x) +#define CPU_SYSREG_OFFSET(x) (CPU_SYSREGS + 8*x) + + .text + .pushsection .hyp.text, "ax" + .align PAGE_SHIFT + +__kvm_hyp_code_start: + .globl __kvm_hyp_code_start + +.macro save_common_regs + // x2: base address for cpu context + // x3: tmp register + + add x3, x2, #CPU_XREG_OFFSET(19) + stp x19, x20, [x3] + stp x21, x22, [x3, #16] + stp x23, x24, [x3, #32] + stp x25, x26, [x3, #48] + stp x27, x28, [x3, #64] + stp x29, lr, [x3, #80] + + mrs x19, sp_el0 + mrs x20, elr_el2 // EL1 PC + mrs x21, spsr_el2 // EL1 pstate + + stp x19, x20, [x3, #96] + str x21, [x3, #112] + + mrs x22, sp_el1 + mrs x23, elr_el1 + mrs x24, spsr_el1 + + str x22, [x2, #CPU_GP_REG_OFFSET(CPU_SP_EL1)] + str x23, [x2, #CPU_GP_REG_OFFSET(CPU_ELR_EL1)] + str x24, [x2, #CPU_SPSR_OFFSET(KVM_SPSR_EL1)] +.endm + +.macro restore_common_regs + // x2: base address for cpu context + // x3: tmp register + + ldr x22, [x2, #CPU_GP_REG_OFFSET(CPU_SP_EL1)] + ldr x23, [x2, #CPU_GP_REG_OFFSET(CPU_ELR_EL1)] + ldr x24, [x2, #CPU_SPSR_OFFSET(KVM_SPSR_EL1)] + + msr sp_el1, x22 + msr elr_el1, x23 + msr spsr_el1, x24 + + add x3, x2, #CPU_XREG_OFFSET(31) // SP_EL0 + ldp x19, x20, [x3] + ldr x21, [x3, #16] + + msr sp_el0, x19 + msr elr_el2, x20 // EL1 PC + msr spsr_el2, x21 // EL1 pstate + + add x3, x2, #CPU_XREG_OFFSET(19) + ldp x19, x20, [x3] + ldp x21, x22, [x3, #16] + ldp x23, x24, [x3, #32] + ldp x25, x26, [x3, #48] + ldp x27, x28, [x3, #64] + ldp x29, lr, [x3, #80] +.endm + +.macro save_host_regs + save_common_regs +.endm + +.macro restore_host_regs + restore_common_regs +.endm + +.macro save_fpsimd + // x2: cpu context address + // x3, x4: tmp regs + add x3, x2, #CPU_GP_REG_OFFSET(CPU_FP_REGS) + fpsimd_save x3, 4 +.endm + +.macro restore_fpsimd + // x2: cpu context address + // x3, x4: tmp regs + add x3, x2, #CPU_GP_REG_OFFSET(CPU_FP_REGS) + fpsimd_restore x3, 4 +.endm + +.macro save_guest_regs + // x0 is the vcpu address + // x1 is the return code, do not corrupt! + // x2 is the cpu context + // x3 is a tmp register + // Guest's x0-x3 are on the stack + + // Compute base to save registers + add x3, x2, #CPU_XREG_OFFSET(4) + stp x4, x5, [x3] + stp x6, x7, [x3, #16] + stp x8, x9, [x3, #32] + stp x10, x11, [x3, #48] + stp x12, x13, [x3, #64] + stp x14, x15, [x3, #80] + stp x16, x17, [x3, #96] + str x18, [x3, #112] + + pop x6, x7 // x2, x3 + pop x4, x5 // x0, x1 + + add x3, x2, #CPU_XREG_OFFSET(0) + stp x4, x5, [x3] + stp x6, x7, [x3, #16] + + save_common_regs +.endm + +.macro restore_guest_regs + // x0 is the vcpu address. + // x2 is the cpu context + // x3 is a tmp register + + // Prepare x0-x3 for later restore + add x3, x2, #CPU_XREG_OFFSET(0) + ldp x4, x5, [x3] + ldp x6, x7, [x3, #16] + push x4, x5 // Push x0-x3 on the stack + push x6, x7 + + // x4-x18 + ldp x4, x5, [x3, #32] + ldp x6, x7, [x3, #48] + ldp x8, x9, [x3, #64] + ldp x10, x11, [x3, #80] + ldp x12, x13, [x3, #96] + ldp x14, x15, [x3, #112] + ldp x16, x17, [x3, #128] + ldr x18, [x3, #144] + + // x19-x29, lr, sp*, elr*, spsr* + restore_common_regs + + // Last bits of the 64bit state + pop x2, x3 + pop x0, x1 + + // Do not touch any register after this! +.endm + +/* + * Macros to perform system register save/restore. + * + * Ordering here is absolutely critical, and must be kept consistent + * in {save,restore}_sysregs, {save,restore}_guest_32bit_state, + * and in kvm_asm.h. + * + * In other words, don't touch any of these unless you know what + * you are doing. + */ +.macro save_sysregs + // x2: base address for cpu context + // x3: tmp register + + add x3, x2, #CPU_SYSREG_OFFSET(MPIDR_EL1) + + mrs x4, vmpidr_el2 + mrs x5, csselr_el1 + mrs x6, sctlr_el1 + mrs x7, actlr_el1 + mrs x8, cpacr_el1 + mrs x9, ttbr0_el1 + mrs x10, ttbr1_el1 + mrs x11, tcr_el1 + mrs x12, esr_el1 + mrs x13, afsr0_el1 + mrs x14, afsr1_el1 + mrs x15, far_el1 + mrs x16, mair_el1 + mrs x17, vbar_el1 + mrs x18, contextidr_el1 + mrs x19, tpidr_el0 + mrs x20, tpidrro_el0 + mrs x21, tpidr_el1 + mrs x22, amair_el1 + mrs x23, cntkctl_el1 + + stp x4, x5, [x3] + stp x6, x7, [x3, #16] + stp x8, x9, [x3, #32] + stp x10, x11, [x3, #48] + stp x12, x13, [x3, #64] + stp x14, x15, [x3, #80] + stp x16, x17, [x3, #96] + stp x18, x19, [x3, #112] + stp x20, x21, [x3, #128] + stp x22, x23, [x3, #144] +.endm + +.macro restore_sysregs + // x2: base address for cpu context + // x3: tmp register + + add x3, x2, #CPU_SYSREG_OFFSET(MPIDR_EL1) + + ldp x4, x5, [x3] + ldp x6, x7, [x3, #16] + ldp x8, x9, [x3, #32] + ldp x10, x11, [x3, #48] + ldp x12, x13, [x3, #64] + ldp x14, x15, [x3, #80] + ldp x16, x17, [x3, #96] + ldp x18, x19, [x3, #112] + ldp x20, x21, [x3, #128] + ldp x22, x23, [x3, #144] + + msr vmpidr_el2, x4 + msr csselr_el1, x5 + msr sctlr_el1, x6 + msr actlr_el1, x7 + msr cpacr_el1, x8 + msr ttbr0_el1, x9 + msr ttbr1_el1, x10 + msr tcr_el1, x11 + msr esr_el1, x12 + msr afsr0_el1, x13 + msr afsr1_el1, x14 + msr far_el1, x15 + msr mair_el1, x16 + msr vbar_el1, x17 + msr contextidr_el1, x18 + msr tpidr_el0, x19 + msr tpidrro_el0, x20 + msr tpidr_el1, x21 + msr amair_el1, x22 + msr cntkctl_el1, x23 +.endm + +.macro activate_traps + ldr x2, [x0, #VCPU_IRQ_LINES] + ldr x1, [x0, #VCPU_HCR_EL2] + orr x2, x2, x1 + msr hcr_el2, x2 + + ldr x2, =(CPTR_EL2_TTA) + msr cptr_el2, x2 + + ldr x2, =(1 << 15) // Trap CP15 Cr=15 + msr hstr_el2, x2 + + mrs x2, mdcr_el2 + and x2, x2, #MDCR_EL2_HPMN_MASK + orr x2, x2, #(MDCR_EL2_TPM | MDCR_EL2_TPMCR) + msr mdcr_el2, x2 +.endm + +.macro deactivate_traps + mov x2, #HCR_RW + msr hcr_el2, x2 + msr cptr_el2, xzr + msr hstr_el2, xzr + + mrs x2, mdcr_el2 + and x2, x2, #MDCR_EL2_HPMN_MASK + msr mdcr_el2, x2 +.endm + +.macro activate_vm + ldr x1, [x0, #VCPU_KVM] + kern_hyp_va x1 + ldr x2, [x1, #KVM_VTTBR] + msr vttbr_el2, x2 +.endm + +.macro deactivate_vm + msr vttbr_el2, xzr +.endm + +__save_sysregs: + save_sysregs + ret + +__restore_sysregs: + restore_sysregs + ret + +__save_fpsimd: + save_fpsimd + ret + +__restore_fpsimd: + restore_fpsimd + ret + +/* + * u64 __kvm_vcpu_run(struct kvm_vcpu *vcpu); + * + * This is the world switch. The first half of the function + * deals with entering the guest, and anything from __kvm_vcpu_return + * to the end of the function deals with reentering the host. + * On the enter path, only x0 (vcpu pointer) must be preserved until + * the last moment. On the exit path, x0 (vcpu pointer) and x1 (exception + * code) must both be preserved until the epilogue. + * In both cases, x2 points to the CPU context we're saving/restoring from/to. + */ +ENTRY(__kvm_vcpu_run) + kern_hyp_va x0 + msr tpidr_el2, x0 // Save the vcpu register + + // Host context + ldr x2, [x0, #VCPU_HOST_CONTEXT] + kern_hyp_va x2 + + save_host_regs + bl __save_fpsimd + bl __save_sysregs + + activate_traps + activate_vm + + // Guest context + add x2, x0, #VCPU_CONTEXT + + bl __restore_sysregs + bl __restore_fpsimd + restore_guest_regs + + // That's it, no more messing around. + clrex + eret + +__kvm_vcpu_return: + // Assume x0 is the vcpu pointer, x1 the return code + // Guest's x0-x3 are on the stack + + // Guest context + add x2, x0, #VCPU_CONTEXT + + save_guest_regs + bl __save_fpsimd + bl __save_sysregs + + deactivate_traps + deactivate_vm + + // Host context + ldr x2, [x0, #VCPU_HOST_CONTEXT] + kern_hyp_va x2 + + bl __restore_sysregs + bl __restore_fpsimd + restore_host_regs + mov x0, x1 + clrex + ret +END(__kvm_vcpu_run) + +// void __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa); +ENTRY(__kvm_tlb_flush_vmid_ipa) + kern_hyp_va x0 + ldr x2, [x0, #KVM_VTTBR] + msr vttbr_el2, x2 + isb + + /* + * We could do so much better if we had the VA as well. + * Instead, we invalidate Stage-2 for this IPA, and the + * whole of Stage-1. Weep... + */ + tlbi ipas2e1is, x1 + dsb sy + tlbi vmalle1is + dsb sy + isb + + msr vttbr_el2, xzr + isb + ret +ENDPROC(__kvm_tlb_flush_vmid_ipa) + +ENTRY(__kvm_flush_vm_context) + tlbi alle1is + ic ialluis + dsb sy + isb + ret +ENDPROC(__kvm_flush_vm_context) + +__kvm_hyp_panic: + adr x0, __hyp_panic_str + adr x1, 1f + ldp x2, x3, [x1] + sub x0, x0, x2 + add x0, x0, x3 + mrs x1, spsr_el2 + mrs x2, elr_el2 + mrs x3, esr_el2 + mrs x4, far_el2 + mrs x5, hpfar_el2 + mrs x6, tpidr_el2 + + mov lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\ + PSR_MODE_EL1h) + msr spsr_el2, lr + ldr lr, =panic + msr elr_el2, lr + eret + + .align 3 +1: .quad HYP_PAGE_OFFSET + .quad PAGE_OFFSET +ENDPROC(__kvm_hyp_panic) + +__hyp_panic_str: + .ascii "HYP panic:\nPS:%08x PC:%p ESR:%p\nFAR:%p HPFAR:%p VCPU:%p\n\0" + + .align 2 + +ENTRY(kvm_call_hyp) + hvc #0 + ret +ENDPROC(kvm_call_hyp) + +.macro invalid_vector label, target + .align 2 +\label: + b \target +ENDPROC(\label) +.endm + + /* None of these should ever happen */ + invalid_vector el2t_sync_invalid, __kvm_hyp_panic + invalid_vector el2t_irq_invalid, __kvm_hyp_panic + invalid_vector el2t_fiq_invalid, __kvm_hyp_panic + invalid_vector el2t_error_invalid, __kvm_hyp_panic + invalid_vector el2h_sync_invalid, __kvm_hyp_panic + invalid_vector el2h_irq_invalid, __kvm_hyp_panic + invalid_vector el2h_fiq_invalid, __kvm_hyp_panic + invalid_vector el2h_error_invalid, __kvm_hyp_panic + invalid_vector el1_sync_invalid, __kvm_hyp_panic + invalid_vector el1_irq_invalid, __kvm_hyp_panic + invalid_vector el1_fiq_invalid, __kvm_hyp_panic + invalid_vector el1_error_invalid, __kvm_hyp_panic + +el1_sync: // Guest trapped into EL2 + push x0, x1 + push x2, x3 + + mrs x1, esr_el2 + lsr x2, x1, #ESR_EL2_EC_SHIFT + + cmp x2, #ESR_EL2_EC_HVC64 + b.ne el1_trap + + mrs x3, vttbr_el2 // If vttbr is valid, the 64bit guest + cbnz x3, el1_trap // called HVC + + /* Here, we're pretty sure the host called HVC. */ + pop x2, x3 + pop x0, x1 + + push lr, xzr + + /* + * Compute the function address in EL2, and shuffle the parameters. + */ + kern_hyp_va x0 + mov lr, x0 + mov x0, x1 + mov x1, x2 + mov x2, x3 + blr lr + + pop lr, xzr + eret + +el1_trap: + /* + * x1: ESR + * x2: ESR_EC + */ + cmp x2, #ESR_EL2_EC_DABT + mov x0, #ESR_EL2_EC_IABT + ccmp x2, x0, #4, ne + b.ne 1f // Not an abort we care about + + /* This is an abort. Check for permission fault */ + and x2, x1, #ESR_EL2_FSC_TYPE + cmp x2, #FSC_PERM + b.ne 1f // Not a permission fault + + /* + * Check for Stage-1 page table walk, which is guaranteed + * to give a valid HPFAR_EL2. + */ + tbnz x1, #7, 1f // S1PTW is set + + /* + * Permission fault, HPFAR_EL2 is invalid. + * Resolve the IPA the hard way using the guest VA. + * Stage-1 translation already validated the memory access rights. + * As such, we can use the EL1 translation regime, and don't have + * to distinguish between EL0 and EL1 access. + */ + mrs x2, far_el2 + at s1e1r, x2 + isb + + /* Read result */ + mrs x3, par_el1 + tbnz x3, #1, 3f // Bail out if we failed the translation + ubfx x3, x3, #12, #36 // Extract IPA + lsl x3, x3, #4 // and present it like HPFAR + b 2f + +1: mrs x3, hpfar_el2 + mrs x2, far_el2 + +2: mrs x0, tpidr_el2 + str x1, [x0, #VCPU_ESR_EL2] + str x2, [x0, #VCPU_FAR_EL2] + str x3, [x0, #VCPU_HPFAR_EL2] + + mov x1, #ARM_EXCEPTION_TRAP + b __kvm_vcpu_return + + /* + * Translation failed. Just return to the guest and + * let it fault again. Another CPU is probably playing + * behind our back. + */ +3: pop x2, x3 + pop x0, x1 + + eret + +el1_irq: + push x0, x1 + push x2, x3 + mrs x0, tpidr_el2 + mov x1, #ARM_EXCEPTION_IRQ + b __kvm_vcpu_return + + .ltorg + + .align 11 + +ENTRY(__kvm_hyp_vector) + ventry el2t_sync_invalid // Synchronous EL2t + ventry el2t_irq_invalid // IRQ EL2t + ventry el2t_fiq_invalid // FIQ EL2t + ventry el2t_error_invalid // Error EL2t + + ventry el2h_sync_invalid // Synchronous EL2h + ventry el2h_irq_invalid // IRQ EL2h + ventry el2h_fiq_invalid // FIQ EL2h + ventry el2h_error_invalid // Error EL2h + + ventry el1_sync // Synchronous 64-bit EL1 + ventry el1_irq // IRQ 64-bit EL1 + ventry el1_fiq_invalid // FIQ 64-bit EL1 + ventry el1_error_invalid // Error 64-bit EL1 + + ventry el1_sync // Synchronous 32-bit EL1 + ventry el1_irq // IRQ 32-bit EL1 + ventry el1_fiq_invalid // FIQ 32-bit EL1 + ventry el1_error_invalid // Error 32-bit EL1 +ENDPROC(__kvm_hyp_vector) + +__kvm_hyp_code_end: + .globl __kvm_hyp_code_end + + .popsection -- 1.8.2.3 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
