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Diffstat (limited to 'arch/arm64/kvm/emulate-nested.c')
| -rw-r--r-- | arch/arm64/kvm/emulate-nested.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c new file mode 100644 index 000000000000..b96662029fb1 --- /dev/null +++ b/arch/arm64/kvm/emulate-nested.c @@ -0,0 +1,203 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2016 - Linaro and Columbia University + * Author: Jintack Lim <jintack.lim@linaro.org> + */ + +#include <linux/kvm.h> +#include <linux/kvm_host.h> + +#include <asm/kvm_emulate.h> +#include <asm/kvm_nested.h> + +#include "hyp/include/hyp/adjust_pc.h" + +#include "trace.h" + +static u64 kvm_check_illegal_exception_return(struct kvm_vcpu *vcpu, u64 spsr) +{ + u64 mode = spsr & PSR_MODE_MASK; + + /* + * Possible causes for an Illegal Exception Return from EL2: + * - trying to return to EL3 + * - trying to return to an illegal M value + * - trying to return to a 32bit EL + * - trying to return to EL1 with HCR_EL2.TGE set + */ + if (mode == PSR_MODE_EL3t || mode == PSR_MODE_EL3h || + mode == 0b00001 || (mode & BIT(1)) || + (spsr & PSR_MODE32_BIT) || + (vcpu_el2_tge_is_set(vcpu) && (mode == PSR_MODE_EL1t || + mode == PSR_MODE_EL1h))) { + /* + * The guest is playing with our nerves. Preserve EL, SP, + * masks, flags from the existing PSTATE, and set IL. + * The HW will then generate an Illegal State Exception + * immediately after ERET. + */ + spsr = *vcpu_cpsr(vcpu); + + spsr &= (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT | + PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT | + PSR_MODE_MASK | PSR_MODE32_BIT); + spsr |= PSR_IL_BIT; + } + + return spsr; +} + +void kvm_emulate_nested_eret(struct kvm_vcpu *vcpu) +{ + u64 spsr, elr, mode; + bool direct_eret; + + /* + * Going through the whole put/load motions is a waste of time + * if this is a VHE guest hypervisor returning to its own + * userspace, or the hypervisor performing a local exception + * return. No need to save/restore registers, no need to + * switch S2 MMU. Just do the canonical ERET. + */ + spsr = vcpu_read_sys_reg(vcpu, SPSR_EL2); + spsr = kvm_check_illegal_exception_return(vcpu, spsr); + + mode = spsr & (PSR_MODE_MASK | PSR_MODE32_BIT); + + direct_eret = (mode == PSR_MODE_EL0t && + vcpu_el2_e2h_is_set(vcpu) && + vcpu_el2_tge_is_set(vcpu)); + direct_eret |= (mode == PSR_MODE_EL2h || mode == PSR_MODE_EL2t); + + if (direct_eret) { + *vcpu_pc(vcpu) = vcpu_read_sys_reg(vcpu, ELR_EL2); + *vcpu_cpsr(vcpu) = spsr; + trace_kvm_nested_eret(vcpu, *vcpu_pc(vcpu), spsr); + return; + } + + preempt_disable(); + kvm_arch_vcpu_put(vcpu); + + elr = __vcpu_sys_reg(vcpu, ELR_EL2); + + trace_kvm_nested_eret(vcpu, elr, spsr); + + /* + * Note that the current exception level is always the virtual EL2, + * since we set HCR_EL2.NV bit only when entering the virtual EL2. + */ + *vcpu_pc(vcpu) = elr; + *vcpu_cpsr(vcpu) = spsr; + + kvm_arch_vcpu_load(vcpu, smp_processor_id()); + preempt_enable(); +} + +static void kvm_inject_el2_exception(struct kvm_vcpu *vcpu, u64 esr_el2, + enum exception_type type) +{ + trace_kvm_inject_nested_exception(vcpu, esr_el2, type); + + switch (type) { + case except_type_sync: + kvm_pend_exception(vcpu, EXCEPT_AA64_EL2_SYNC); + vcpu_write_sys_reg(vcpu, esr_el2, ESR_EL2); + break; + case except_type_irq: + kvm_pend_exception(vcpu, EXCEPT_AA64_EL2_IRQ); + break; + default: + WARN_ONCE(1, "Unsupported EL2 exception injection %d\n", type); + } +} + +/* + * Emulate taking an exception to EL2. + * See ARM ARM J8.1.2 AArch64.TakeException() + */ +static int kvm_inject_nested(struct kvm_vcpu *vcpu, u64 esr_el2, + enum exception_type type) +{ + u64 pstate, mode; + bool direct_inject; + + if (!vcpu_has_nv(vcpu)) { + kvm_err("Unexpected call to %s for the non-nesting configuration\n", + __func__); + return -EINVAL; + } + + /* + * As for ERET, we can avoid doing too much on the injection path by + * checking that we either took the exception from a VHE host + * userspace or from vEL2. In these cases, there is no change in + * translation regime (or anything else), so let's do as little as + * possible. + */ + pstate = *vcpu_cpsr(vcpu); + mode = pstate & (PSR_MODE_MASK | PSR_MODE32_BIT); + + direct_inject = (mode == PSR_MODE_EL0t && + vcpu_el2_e2h_is_set(vcpu) && + vcpu_el2_tge_is_set(vcpu)); + direct_inject |= (mode == PSR_MODE_EL2h || mode == PSR_MODE_EL2t); + + if (direct_inject) { + kvm_inject_el2_exception(vcpu, esr_el2, type); + return 1; + } + + preempt_disable(); + + /* + * We may have an exception or PC update in the EL0/EL1 context. + * Commit it before entering EL2. + */ + __kvm_adjust_pc(vcpu); + + kvm_arch_vcpu_put(vcpu); + + kvm_inject_el2_exception(vcpu, esr_el2, type); + + /* + * A hard requirement is that a switch between EL1 and EL2 + * contexts has to happen between a put/load, so that we can + * pick the correct timer and interrupt configuration, among + * other things. + * + * Make sure the exception actually took place before we load + * the new context. + */ + __kvm_adjust_pc(vcpu); + + kvm_arch_vcpu_load(vcpu, smp_processor_id()); + preempt_enable(); + + return 1; +} + +int kvm_inject_nested_sync(struct kvm_vcpu *vcpu, u64 esr_el2) +{ + return kvm_inject_nested(vcpu, esr_el2, except_type_sync); +} + +int kvm_inject_nested_irq(struct kvm_vcpu *vcpu) +{ + /* + * Do not inject an irq if the: + * - Current exception level is EL2, and + * - virtual HCR_EL2.TGE == 0 + * - virtual HCR_EL2.IMO == 0 + * + * See Table D1-17 "Physical interrupt target and masking when EL3 is + * not implemented and EL2 is implemented" in ARM DDI 0487C.a. + */ + + if (vcpu_is_el2(vcpu) && !vcpu_el2_tge_is_set(vcpu) && + !(__vcpu_sys_reg(vcpu, HCR_EL2) & HCR_IMO)) + return 1; + + /* esr_el2 value doesn't matter for exits due to irqs. */ + return kvm_inject_nested(vcpu, 0, except_type_irq); +} |