linux-kernel - Re: [RFC 11/55] KVM: arm64: Emulate taking an exception to the guest hypervisor

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Message-ID: <jpgvao7g1du.fsf@linux.bootlegged.copy>
Date:   Wed, 07 Jun 2017 13:21:01 -0400
From:   Bandan Das <bsd@...hat.com>
To:     Jintack Lim <jintack.lim@...aro.org>
Cc:     KVM General <kvm@...r.kernel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        kvmarm@...ts.cs.columbia.edu,
        Shih-Wei Li <shihwei@...columbia.edu>,
        lorenzo.pieralisi@....com, linux@...linux.org.uk,
        arm-mail-list <linux-arm-kernel@...ts.infradead.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Andre Przywara <andre.przywara@....com>, kevin.brodsky@....com,
        wcohen@...hat.com, anna-maria@...utronix.de, geoff@...radead.org,
        lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [RFC 11/55] KVM: arm64: Emulate taking an exception to the guest hypervisor

Jintack Lim <jintack.lim@...aro.org> writes:

> Compilation on 32bit arm architecture will fail without them.
...
>> It seems these functions are
>> defined separately in 32/64 bit specific header files. Or is it that
>> 64 bit compilation also depends on the 32 bit header file ?
>
> It's only for 32bit architecture. For example, kvm_inject_nested_irq()
> is called in virt/kvm/arm/vgic/vgic.c which is shared between 32 and
> 64 bit.

Ah, that's the catch! Thanks for clearing this up!

>>
>> Bandan
>>
>>> Thanks,
>>> Jintack
>>>
>>>>
>>>> Bandan
>>>>
>>>>>  static inline void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu) { };
>>>>>  static inline void kvm_arm_restore_shadow_state(struct kvm_vcpu *vcpu) { };
>>>>>  static inline void kvm_arm_init_cpu_context(kvm_cpu_context_t *cpu_ctxt) { };
>>>>> diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
>>>>> index 8892c82..0987ee4 100644
>>>>> --- a/arch/arm64/include/asm/kvm_emulate.h
>>>>> +++ b/arch/arm64/include/asm/kvm_emulate.h
>>>>> @@ -42,6 +42,25 @@
>>>>>  void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
>>>>>  void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
>>>>>
>>>>> +#ifdef CONFIG_KVM_ARM_NESTED_HYP
>>>>> +int kvm_inject_nested_sync(struct kvm_vcpu *vcpu, u64 esr_el2);
>>>>> +int kvm_inject_nested_irq(struct kvm_vcpu *vcpu);
>>>>> +#else
>>>>> +static inline int kvm_inject_nested_sync(struct kvm_vcpu *vcpu, u64 esr_el2)
>>>>> +{
>>>>> +     kvm_err("Unexpected call to %s for the non-nesting configuration\n",
>>>>> +              __func__);
>>>>> +     return -EINVAL;
>>>>> +}
>>>>> +
>>>>> +static inline int kvm_inject_nested_irq(struct kvm_vcpu *vcpu)
>>>>> +{
>>>>> +     kvm_err("Unexpected call to %s for the non-nesting configuration\n",
>>>>> +              __func__);
>>>>> +     return -EINVAL;
>>>>> +}
>>>>> +#endif
>>>>> +
>>>>>  void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu);
>>>>>  void kvm_arm_restore_shadow_state(struct kvm_vcpu *vcpu);
>>>>>  void kvm_arm_init_cpu_context(kvm_cpu_context_t *cpu_ctxt);
>>>>> diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
>>>>> index 7811d27..b342bdd 100644
>>>>> --- a/arch/arm64/kvm/Makefile
>>>>> +++ b/arch/arm64/kvm/Makefile
>>>>> @@ -34,3 +34,5 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-its.o
>>>>>  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/irqchip.o
>>>>>  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/arch_timer.o
>>>>>  kvm-$(CONFIG_KVM_ARM_PMU) += $(KVM)/arm/pmu.o
>>>>> +
>>>>> +kvm-$(CONFIG_KVM_ARM_NESTED_HYP) += emulate-nested.o
>>>>> diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
>>>>> new file mode 100644
>>>>> index 0000000..59d147f
>>>>> --- /dev/null
>>>>> +++ b/arch/arm64/kvm/emulate-nested.c
>>>>> @@ -0,0 +1,66 @@
>>>>> +/*
>>>>> + * Copyright (C) 2016 - Columbia University
>>>>> + * Author: Jintack Lim <jintack@...columbia.edu>
>>>>> + *
>>>>> + * 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/kvm.h>
>>>>> +#include <linux/kvm_host.h>
>>>>> +
>>>>> +#include <asm/kvm_emulate.h>
>>>>> +
>>>>> +#include "trace.h"
>>>>> +
>>>>> +#define      EL2_EXCEPT_SYNC_OFFSET  0x400
>>>>> +#define      EL2_EXCEPT_ASYNC_OFFSET 0x480
>>>>> +
>>>>> +
>>>>> +/*
>>>>> + *  Emulate taking an exception. See ARM ARM J8.1.2 AArch64.TakeException()
>>>>> + */
>>>>> +static int kvm_inject_nested(struct kvm_vcpu *vcpu, u64 esr_el2,
>>>>> +                          int exception_offset)
>>>>> +{
>>>>> +     int ret = 1;
>>>>> +     kvm_cpu_context_t *ctxt = &vcpu->arch.ctxt;
>>>>> +
>>>>> +     /* We don't inject an exception recursively to virtual EL2 */
>>>>> +     if (vcpu_mode_el2(vcpu))
>>>>> +             BUG();
>>>>> +
>>>>> +     ctxt->el2_regs[SPSR_EL2] = *vcpu_cpsr(vcpu);
>>>>> +     ctxt->el2_regs[ELR_EL2] = *vcpu_pc(vcpu);
>>>>> +     ctxt->el2_regs[ESR_EL2] = esr_el2;
>>>>> +
>>>>> +     /* On an exception, PSTATE.SP = 1 */
>>>>> +     *vcpu_cpsr(vcpu) = PSR_MODE_EL2h;
>>>>> +     *vcpu_cpsr(vcpu) |=  (PSR_A_BIT | PSR_F_BIT | PSR_I_BIT | PSR_D_BIT);
>>>>> +     *vcpu_pc(vcpu) = ctxt->el2_regs[VBAR_EL2] + exception_offset;
>>>>> +
>>>>> +     trace_kvm_inject_nested_exception(vcpu, esr_el2, *vcpu_pc(vcpu));
>>>>> +
>>>>> +     return ret;
>>>>> +}
>>>>> +
>>>>> +int kvm_inject_nested_sync(struct kvm_vcpu *vcpu, u64 esr_el2)
>>>>> +{
>>>>> +     return kvm_inject_nested(vcpu, esr_el2, EL2_EXCEPT_SYNC_OFFSET);
>>>>> +}
>>>>> +
>>>>> +int kvm_inject_nested_irq(struct kvm_vcpu *vcpu)
>>>>> +{
>>>>> +     u64 esr_el2 = kvm_vcpu_get_hsr(vcpu);
>>>>> +     /* We supports only IRQ and FIQ, so the esr_el2 is not updated. */
>>>>> +     return kvm_inject_nested(vcpu, esr_el2, EL2_EXCEPT_ASYNC_OFFSET);
>>>>> +}
>>>>> diff --git a/arch/arm64/kvm/trace.h b/arch/arm64/kvm/trace.h
>>>>> index 7fb0008..7c86cfb 100644
>>>>> --- a/arch/arm64/kvm/trace.h
>>>>> +++ b/arch/arm64/kvm/trace.h
>>>>> @@ -167,6 +167,26 @@
>>>>>  );
>>>>>
>>>>>
>>>>> +TRACE_EVENT(kvm_inject_nested_exception,
>>>>> +     TP_PROTO(struct kvm_vcpu *vcpu, unsigned long esr_el2,
>>>>> +              unsigned long pc),
>>>>> +     TP_ARGS(vcpu, esr_el2, pc),
>>>>> +
>>>>> +     TP_STRUCT__entry(
>>>>> +             __field(struct kvm_vcpu *,      vcpu)
>>>>> +             __field(unsigned long,          esr_el2)
>>>>> +             __field(unsigned long,          pc)
>>>>> +     ),
>>>>> +
>>>>> +     TP_fast_assign(
>>>>> +             __entry->vcpu = vcpu;
>>>>> +             __entry->esr_el2 = esr_el2;
>>>>> +             __entry->pc = pc;
>>>>> +     ),
>>>>> +
>>>>> +     TP_printk("vcpu: %p, inject exception to vEL2: ESR_EL2 0x%lx, vector: 0x%016lx",
>>>>> +               __entry->vcpu, __entry->esr_el2, __entry->pc)
>>>>> +);
>>>>>  #endif /* _TRACE_ARM64_KVM_H */
>>>>>
>>>>>  #undef TRACE_INCLUDE_PATH
>>>> _______________________________________________
>>>> kvmarm mailing list
>>>> kvmarm@...ts.cs.columbia.edu
>>>> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

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