[PATCH 07/11] KVM: arm64: Inject AArch64 exceptions from HYP

[Marc Zyngier]

On 2020-10-26 14:22, Mark Rutland wrote:
> On Mon, Oct 26, 2020 at 01:34:46PM +0000, Marc Zyngier wrote:
>> Move the AArch64 exception injection code from EL1 to HYP, leaving
>> only the ESR_EL1 updates to EL1. In order to come with the differences
>> between VHE and nVHE, two set of system register accessors are 
>> provided.
>> 
>> SPSR, ELR, PC and PSTATE are now completely handled in the hypervisor.
>> 
>> Signed-off-by: Marc Zyngier <maz at kernel.org>
> 
>>  void kvm_inject_exception(struct kvm_vcpu *vcpu)
>>  {
>> +	switch (vcpu->arch.flags & KVM_ARM64_EXCEPT_MASK) {
>> +	case KVM_ARM64_EXCEPT_AA64_EL1_SYNC:
>> +		enter_exception64(vcpu, PSR_MODE_EL1h, except_type_sync);
>> +		break;
>> +	case KVM_ARM64_EXCEPT_AA64_EL1_IRQ:
>> +		enter_exception64(vcpu, PSR_MODE_EL1h, except_type_irq);
>> +		break;
>> +	case KVM_ARM64_EXCEPT_AA64_EL1_FIQ:
>> +		enter_exception64(vcpu, PSR_MODE_EL1h, except_type_fiq);
>> +		break;
>> +	case KVM_ARM64_EXCEPT_AA64_EL1_SERR:
>> +		enter_exception64(vcpu, PSR_MODE_EL1h, except_type_serror);
>> +		break;
>> +	default:
>> +		/* EL2 are unimplemented until we get NV. One day. */
>> +		break;
>> +	}
>>  }
> 
> Huh, we're going to allow EL1 to inject IRQ/FIQ/SERROR *exceptions*
> directly, rather than pending those via HCR_EL2.{VI,VF,VSE}? We never
> used to have code to do that.

True, and I feel like I got carried away while thinking of NV.
Though James had some "interesting" use case [1] lately...

> If we're going to support that we'll need to check against the DAIF 
> bits
> to make sure we don't inject an exception that can't be architecturally
> taken.

Nah, forget it. Unless we really need to implement something like James'
idea, I'd rather drop this altogether.

> I guess we'll tighten that up along with the synchronous exception
> checks, but given those three cases aren't needed today it might be
> worth removing them from the switch for now and/or adding a comment to
> that effect.

Agreed.

         M.

[1] https://lore.kernel.org/r/20201023165108.15061-1-james.morse@arm.com
-- 
Jazz is not dead. It just smells funny...