[PATCH v2 13/25] KVM: arm64: vgic-v3: Add ICV_BPR0_EL1 handler

[Marc Zyngier]

On 06/06/17 13:11, Christoffer Dall wrote:
> On Thu, Jun 01, 2017 at 11:21:05AM +0100, Marc Zyngier wrote:
>> Add a handler for reading/writing the guest's view of the ICC_BPR0_EL1
>> register, which is located in the ICH_VMCR_EL2.BPR0 field.
>>
>> Reviewed-by: Eric Auger <eric.auger at redhat.com>
>> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
>> ---
>>  arch/arm64/include/asm/sysreg.h |  1 +
>>  virt/kvm/arm/hyp/vgic-v3-sr.c   | 36 ++++++++++++++++++++++++++++++++++++
>>  2 files changed, 37 insertions(+)
>>
>> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
>> index bd000686194a..d20be0b28ca4 100644
>> --- a/arch/arm64/include/asm/sysreg.h
>> +++ b/arch/arm64/include/asm/sysreg.h
>> @@ -180,6 +180,7 @@
>>  
>>  #define SYS_VBAR_EL1			sys_reg(3, 0, 12, 0, 0)
>>  
>> +#define SYS_ICC_BPR0_EL1		sys_reg(3, 0, 12, 8, 3)
>>  #define SYS_ICC_AP1Rn_EL1(n)		sys_reg(3, 0, 12, 9, n)
>>  #define SYS_ICC_DIR_EL1			sys_reg(3, 0, 12, 11, 1)
>>  #define SYS_ICC_SGI1R_EL1		sys_reg(3, 0, 12, 11, 5)
>> diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c
>> index 42ac9ee7650a..54a8e828c85b 100644
>> --- a/virt/kvm/arm/hyp/vgic-v3-sr.c
>> +++ b/virt/kvm/arm/hyp/vgic-v3-sr.c
>> @@ -688,11 +688,41 @@ static void __hyp_text __vgic_v3_write_igrpen1(struct kvm_vcpu *vcpu, u32 vmcr,
>>  	__vgic_v3_write_vmcr(vmcr);
>>  }
>>  
>> +static void __hyp_text __vgic_v3_read_bpr0(struct kvm_vcpu *vcpu, u32 vmcr, int rt)
>> +{
>> +	vcpu_set_reg(vcpu, rt, __vgic_v3_get_bpr0(vmcr));
>> +}
>> +
>>  static void __hyp_text __vgic_v3_read_bpr1(struct kvm_vcpu *vcpu, u32 vmcr, int rt)
>>  {
>>  	vcpu_set_reg(vcpu, rt, __vgic_v3_get_bpr1(vmcr));
>>  }
>>  
>> +static void __hyp_text __vgic_v3_write_bpr0(struct kvm_vcpu *vcpu, u32 vmcr, int rt)
>> +{
>> +	u64 val = vcpu_get_reg(vcpu, rt);
>> +	u8 bpr_min = 7 - vtr_to_nr_pre_bits(read_gicreg(ICH_VTR_EL2));
>> +
>> +	/* Enforce BPR limiting */
>> +	if (val < bpr_min)
>> +		val = bpr_min;
>> +
>> +	val <<= ICH_VMCR_BPR0_SHIFT;
>> +	val &= ICH_VMCR_BPR0_MASK;
>> +	vmcr &= ~ICH_VMCR_BPR0_MASK;
>> +	vmcr |= val;
>> +
>> +	if (vmcr & ICH_VMCR_CBPR_MASK) {
>> +		val = __vgic_v3_get_bpr1(vmcr);
>> +		val <<= ICH_VMCR_BPR1_SHIFT;
>> +		val &= ICH_VMCR_BPR1_MASK;
>> +		vmcr &= ~ICH_VMCR_BPR1_MASK;
>> +		vmcr |= val;
>> +	}
> 
> I don't understand why this block is needed?

If you have CBPR already set, and then update BPR0, you need to make
sure that BPR1 gets updated as well. You could hope that the HW would do
it for you, but since we're erratum workaround land...

Thanks,

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