Re: [PATCH v4 09/66] KVM: arm64: nv: Support virtual EL2 exceptions

[Zenghui Yu <yuzenghui@xxxxxxxxxx>]

On 2021/5/11 0:58, Marc Zyngier wrote:
> From: Jintack Lim <jintack.lim@xxxxxxxxxx>
>
> Support injecting exceptions and performing exception returns to and
> from virtual EL2.  This must be done entirely in software except when
> taking an exception from vEL0 to vEL2 when the virtual HCR_EL2.{E2H,TGE}
> == {1,1}  (a VHE guest hypervisor).
>
> Signed-off-by: Jintack Lim <jintack.lim@xxxxxxxxxx>
> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxx>
> [maz: switch to common exception injection framework]
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
>  arch/arm64/include/asm/kvm_arm.h     |  17 +++
>  arch/arm64/include/asm/kvm_emulate.h |  10 ++
>  arch/arm64/kvm/Makefile              |   2 +-
>  arch/arm64/kvm/emulate-nested.c      | 176 +++++++++++++++++++++++++++
>  arch/arm64/kvm/hyp/exception.c       |  45 +++++--
>  arch/arm64/kvm/inject_fault.c        |  63 ++++++++--
>  arch/arm64/kvm/trace_arm.h           |  59 +++++++++
>  7 files changed, 354 insertions(+), 18 deletions(-)
>  create mode 100644 arch/arm64/kvm/emulate-nested.c

[...]

>  static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr)
>  {
>  	unsigned long cpsr = *vcpu_cpsr(vcpu);
>  	bool is_aarch32 = vcpu_mode_is_32bit(vcpu);
>  	u32 esr = 0;
>  
> -	vcpu->arch.flags |= (KVM_ARM64_EXCEPT_AA64_EL1		|
> -			     KVM_ARM64_EXCEPT_AA64_ELx_SYNC	|
> -			     KVM_ARM64_PENDING_EXCEPTION);
> -
> -	vcpu_write_sys_reg(vcpu, addr, FAR_EL1);
> +	pend_sync_exception(vcpu);
>  
>  	/*
>  	 * Build an {i,d}abort, depending on the level and the
> @@ -45,16 +79,22 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr
>  	if (!is_iabt)
>  		esr |= ESR_ELx_EC_DABT_LOW << ESR_ELx_EC_SHIFT;
>  
> -	vcpu_write_sys_reg(vcpu, esr | ESR_ELx_FSC_EXTABT, ESR_EL1);
> +	esr |= ESR_ELx_FSC_EXTABT;
> +
> +	if (vcpu->arch.flags & KVM_ARM64_EXCEPT_AA64_EL1) {

This isn't the right way to pick between EL1 and EL2 since
KVM_ARM64_EXCEPT_AA64_EL1 is (0 << 11), we will not be able
to inject abort to EL1 that way.

> +		vcpu_write_sys_reg(vcpu, addr, FAR_EL1);
> +		vcpu_write_sys_reg(vcpu, esr, ESR_EL1);
> +	} else {
> +		vcpu_write_sys_reg(vcpu, addr, FAR_EL2);
> +		vcpu_write_sys_reg(vcpu, esr, ESR_EL2);
> +	}
>  }
>  
>  static void inject_undef64(struct kvm_vcpu *vcpu)
>  {
>  	u32 esr = (ESR_ELx_EC_UNKNOWN << ESR_ELx_EC_SHIFT);
>  
> -	vcpu->arch.flags |= (KVM_ARM64_EXCEPT_AA64_EL1		|
> -			     KVM_ARM64_EXCEPT_AA64_ELx_SYNC	|
> -			     KVM_ARM64_PENDING_EXCEPTION);
> +	pend_sync_exception(vcpu);
>  
>  	/*
>  	 * Build an unknown exception, depending on the instruction
> @@ -63,7 +103,10 @@ static void inject_undef64(struct kvm_vcpu *vcpu)
>  	if (kvm_vcpu_trap_il_is32bit(vcpu))
>  		esr |= ESR_ELx_IL;
>  
> -	vcpu_write_sys_reg(vcpu, esr, ESR_EL1);
> +	if (vcpu->arch.flags & KVM_ARM64_EXCEPT_AA64_EL1)
> +		vcpu_write_sys_reg(vcpu, esr, ESR_EL1);
> +	else
> +		vcpu_write_sys_reg(vcpu, esr, ESR_EL2);

Same here.

Thanks,
Zenghui