Re: [PATCH 15/21] arm64: KVM: Add panic handling

[Marc Zyngier <marc.zyngier@arm.com>]

On 16/11/15 14:16, Mark Rutland wrote:
>> diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
>> index 06d3e20..cdc2a96 100644
>> --- a/arch/arm64/kvm/hyp/switch.c
>> +++ b/arch/arm64/kvm/hyp/switch.c
>> @@ -140,3 +140,38 @@ int __hyp_text __guest_run(struct kvm_vcpu *vcpu)
>>  
>>  	return exit_code;
>>  }
>> +
>> +static const char *__hyp_panic_string = "HYP panic:\nPS:%08x PC:%p ESR:%p\nFAR:%p HPFAR:%p PAR:%p\nVCPU:%p\n";
> 
> I assume that if [1] goes in we'll update this to match.

Definitely.

>> +
>> +void __hyp_text __noreturn __hyp_panic(void)
>> +{
>> +	u64 spsr = read_sysreg(spsr_el2);
>> +	u64 elr = read_sysreg(elr_el2);
>> +	u64 par = read_sysreg(par_el1);
>> +
>> +	if (read_sysreg(vttbr_el2)) {
>> +		struct kvm_vcpu *vcpu;
>> +		struct kvm_cpu_context *host_ctxt;
>> +
>> +		vcpu = (struct kvm_vcpu *)read_sysreg(tpidr_el2);
>> +		host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
>> +		__deactivate_traps(vcpu);
>> +		__deactivate_vm(vcpu);
>> +		__sysreg_restore_state(host_ctxt);
>> +
>> +		write_sysreg(host_ctxt->gp_regs.sp_el1, sp_el1);
> 
> __sysreg_restore_state restores the host sp_el1, no?

Better safe than sorry! ;-) Looks like a leftover from some ancient
version... I'll fix that.

>> +	}
>> +
>> +	/* Call panic for real */
>> +	while (1) {
>> +		unsigned long str_va = (unsigned long)__hyp_panic_string;
>> +
>> +		str_va -= HYP_PAGE_OFFSET;
>> +		str_va += PAGE_OFFSET;
>> +		__hyp_do_panic(str_va,
>> +			       spsr,  elr,
>> +			       read_sysreg(esr_el2),   read_sysreg(far_el2),
>> +			       read_sysreg(hpfar_el2), par,
>> +			       read_sysreg(tpidr_el2));
>> +	}
>> +}
> 
> I think the while (1) here is confusing.
> 
> Can we not jsut declare str_va at the start of the function and get rid
> of the loop?

The while(1) is to prevent GCC from screaming (it otherwise believes
that the function actually returns, despite the __noreturn attribute).

Or were you thinking of something else?

	M.
-- 
Jazz is not dead. It just smells funny...