Re: [PATCH 27/59] KVM: arm64: nv: Respect virtual HCR_EL2.TVM and TRVM settings

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 26/06/2019 07:55, Julien Thierry wrote:
> 
> 
> On 06/21/2019 10:38 AM, Marc Zyngier wrote:
>> From: Jintack Lim <jintack.lim@xxxxxxxxxx>
>>
>> Forward the EL1 virtual memory register traps to the virtual EL2 if they
>> are not coming from the virtual EL2 and the virtual HCR_EL2.TVM or TRVM
>> bit is set.
>>
>> This is for recursive nested virtualization.
>>
>> Signed-off-by: Jintack Lim <jintack.lim@xxxxxxxxxx>
>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>> ---
>>  arch/arm64/kvm/sys_regs.c | 24 ++++++++++++++++++++++++
>>  1 file changed, 24 insertions(+)
>>
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index 582d62aa48b7..0f74b9277a86 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -436,6 +436,27 @@ static bool access_dcsw(struct kvm_vcpu *vcpu,
>>  	return true;
>>  }
>>  
>> +/* This function is to support the recursive nested virtualization */
>> +static bool forward_vm_traps(struct kvm_vcpu *vcpu, struct sys_reg_params *p)
>> +{
>> +	u64 hcr_el2 = __vcpu_sys_reg(vcpu, HCR_EL2);
>> +
>> +	/* If a trap comes from the virtual EL2, the host hypervisor handles. */
>> +	if (vcpu_mode_el2(vcpu))
>> +		return false;
>> +
>> +	/*
>> +	 * If the virtual HCR_EL2.TVM or TRVM bit is set, we need to foward
>> +	 * this trap to the virtual EL2.
>> +	 */
>> +	if ((hcr_el2 & HCR_TVM) && p->is_write)
>> +		return true;
>> +	else if ((hcr_el2 & HCR_TRVM) && !p->is_write)
>> +		return true;
>> +
>> +	return false;
>> +}
>> +
>>  /*
>>   * Generic accessor for VM registers. Only called as long as HCR_TVM
>>   * is set. If the guest enables the MMU, we stop trapping the VM
>> @@ -452,6 +473,9 @@ static bool access_vm_reg(struct kvm_vcpu *vcpu,
>>  	if (el12_reg(p) && forward_nv_traps(vcpu))
>>  		return false;
>>  
>> +	if (!el12_reg(p) && forward_vm_traps(vcpu, p))
>> +		return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
> 
> Since we already have forward_traps(), isn't this just:
> 
> 	if (!el12_reg(p) && forward_traps(vcpu, p->is_write ? HCR_TVM : HCR_TRVM))
> 		return true;
> 
> We could maybe simplify forward_vm_traps() to just call forward_traps()
> similar to forward_nv_traps().

Odd. I remember doing something like that. Where has it gone? Yes, this
looks sensible.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm



[Index of Archives]     [Linux KVM]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux