Re: [PATCH v2 07/15] KVM: arm64: handle ITS related GICv3 redistributor registers

From: Andre Przywara <andre.przywara@arm.com>
To: Eric Auger <eric.auger@linaro.org>,
	"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>
Cc: Marc Zyngier <Marc.Zyngier@arm.com>,
	Pavel Fedin <p.fedin@samsung.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"christoffer.dall@linaro.org" <christoffer.dall@linaro.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH v2 07/15] KVM: arm64: handle ITS related GICv3 redistributor registers
Date: Mon, 24 Aug 2015 19:08:19 +0100	[thread overview]
Message-ID: <55DB5D93.3090007@arm.com> (raw)
In-Reply-To: <55CC8AE2.2070807@linaro.org>

Hi Eric,

On 13/08/15 13:17, Eric Auger wrote:
> On 07/10/2015 04:21 PM, Andre Przywara wrote:
>> In the GICv3 redistributor there are the PENDBASER and PROPBASER
>> registers which we did not emulate so far, as they only make sense
>> when having an ITS. In preparation for that emulate those MMIO
>> accesses by storing the 64-bit data written into it into a variable
>> which we later read in the ITS emulation.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> ---
>>  include/kvm/arm_vgic.h      |  8 ++++++++
>>  virt/kvm/arm/vgic-v3-emul.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>  virt/kvm/arm/vgic.c         | 35 +++++++++++++++++++++++++++++++++++
>>  virt/kvm/arm/vgic.h         |  4 ++++
>>  4 files changed, 91 insertions(+)
>>
>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
>> index 3ee063b..8c6cb0e 100644
>> --- a/include/kvm/arm_vgic.h
>> +++ b/include/kvm/arm_vgic.h
>> @@ -256,6 +256,14 @@ struct vgic_dist {
>>  	struct vgic_vm_ops	vm_ops;
>>  	struct vgic_io_device	dist_iodev;
>>  	struct vgic_io_device	*redist_iodevs;
>> +
>> +	/* Address of LPI configuration table shared by all redistributors */
>> +	u64			propbaser;
>> +
>> +	/* Addresses of LPI pending tables per redistributor */
>> +	u64			*pendbaser;
>> +
>> +	bool			lpis_enabled;
>>  };
>>  
>>  struct vgic_v2_cpu_if {
>> diff --git a/virt/kvm/arm/vgic-v3-emul.c b/virt/kvm/arm/vgic-v3-emul.c
>> index a8cf669..5269ad1 100644
>> --- a/virt/kvm/arm/vgic-v3-emul.c
>> +++ b/virt/kvm/arm/vgic-v3-emul.c
>> @@ -651,6 +651,38 @@ static bool handle_mmio_cfg_reg_redist(struct kvm_vcpu *vcpu,
>>  	return vgic_handle_cfg_reg(reg, mmio, offset);
>>  }
>>  
>> +/* We don't trigger any actions here, just store the register value */
>> +static bool handle_mmio_propbaser_redist(struct kvm_vcpu *vcpu,
>> +					 struct kvm_exit_mmio *mmio,
>> +					 phys_addr_t offset)
>> +{
>> +	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
>> +	int mode = ACCESS_READ_VALUE;
>> +
>> +	/* Storing a value with LPIs already enabled is undefined */
>> +	mode |= dist->lpis_enabled ? ACCESS_WRITE_IGNORED : ACCESS_WRITE_VALUE;
>> +	vgic_handle_base_register(vcpu, mmio, offset, &dist->propbaser, mode);
>> +
>> +	return false;
>> +}
>> +
>> +/* We don't trigger any actions here, just store the register value */
>> +static bool handle_mmio_pendbaser_redist(struct kvm_vcpu *vcpu,
>> +					 struct kvm_exit_mmio *mmio,
>> +					 phys_addr_t offset)
>> +{
>> +	struct kvm_vcpu *rdvcpu = mmio->private;
>> +	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
>> +	int mode = ACCESS_READ_VALUE;
>> +
>> +	/* Storing a value with LPIs already enabled is undefined */
>> +	mode |= dist->lpis_enabled ? ACCESS_WRITE_IGNORED : ACCESS_WRITE_VALUE;
>> +	vgic_handle_base_register(vcpu, mmio, offset,
>> +				  &dist->pendbaser[rdvcpu->vcpu_id], mode);
>> +
>> +	return false;
>> +}
>> +
>>  #define SGI_base(x) ((x) + SZ_64K)
>>  
>>  static const struct vgic_io_range vgic_redist_ranges[] = {
>> @@ -679,6 +711,18 @@ static const struct vgic_io_range vgic_redist_ranges[] = {
>>  		.handle_mmio    = handle_mmio_raz_wi,
>>  	},
>>  	{
>> +		.base		= GICR_PENDBASER,
>> +		.len		= 0x08,
>> +		.bits_per_irq	= 0,
>> +		.handle_mmio	= handle_mmio_pendbaser_redist,
>> +	},
>> +	{
>> +		.base		= GICR_PROPBASER,
>> +		.len		= 0x08,
>> +		.bits_per_irq	= 0,
>> +		.handle_mmio	= handle_mmio_propbaser_redist,
>> +	},
>> +	{
>>  		.base           = GICR_IDREGS,
>>  		.len            = 0x30,
>>  		.bits_per_irq   = 0,
>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>> index 15e447f..49ee92b 100644
>> --- a/virt/kvm/arm/vgic.c
>> +++ b/virt/kvm/arm/vgic.c
>> @@ -446,6 +446,41 @@ void vgic_reg_access(struct kvm_exit_mmio *mmio, u32 *reg,
>>  	}
>>  }
>>  
>> +/* handle a 64-bit register access */
>> +void vgic_handle_base_register(struct kvm_vcpu *vcpu,
>> +			       struct kvm_exit_mmio *mmio,
>> +			       phys_addr_t offset, u64 *basereg,
>> +			       int mode)
>> +{
> why do we have vcpu in the proto? I don't see it used. Also if it were
> can't we fetch it from mmio->private?
> 
> why not renaming this into something like vgic_reg64_access as par
> vgic_reg_access 32b flavor above. vgic_handle* usually is the name of
> the region handler returning bool?

Makes sense, I both renamed the function and removed the vcpu parameter.
I need to check whether we need the vcpu to do some endianness checks in
the future, though. Using mmio->private would be a hack, then.

Cheers,
Andre.

> 
>> +	u32 reg;
>> +	u64 breg;
>> +
>> +	switch (offset & ~3) {
>> +	case 0x00:
>> +		breg = *basereg;
>> +		reg = lower_32_bits(breg);
>> +		vgic_reg_access(mmio, &reg, offset & 3, mode);
>> +		if (mmio->is_write && (mode & ACCESS_WRITE_VALUE)) {
>> +			breg &= GENMASK_ULL(63, 32);
>> +			breg |= reg;
>> +			*basereg = breg;
>> +		}
>> +		break;
>> +	case 0x04:
>> +		breg = *basereg;
>> +		reg = upper_32_bits(breg);
>> +		vgic_reg_access(mmio, &reg, offset & 3, mode);
>> +		if (mmio->is_write && (mode & ACCESS_WRITE_VALUE)) {
>> +			breg  = lower_32_bits(breg);
>> +			breg |= (u64)reg << 32;
>> +			*basereg = breg;
>> +		}
>> +		break;
>> +	}
>> +}
>> +
>> +
>> +
> some spare white lines
> 
> Best Regards
> 
> Eric
>>  bool handle_mmio_raz_wi(struct kvm_vcpu *vcpu, struct kvm_exit_mmio *mmio,
>>  			phys_addr_t offset)
>>  {
>> diff --git a/virt/kvm/arm/vgic.h b/virt/kvm/arm/vgic.h
>> index a093f5c..b2d791c 100644
>> --- a/virt/kvm/arm/vgic.h
>> +++ b/virt/kvm/arm/vgic.h
>> @@ -71,6 +71,10 @@ void vgic_reg_access(struct kvm_exit_mmio *mmio, u32 *reg,
>>  		     phys_addr_t offset, int mode);
>>  bool handle_mmio_raz_wi(struct kvm_vcpu *vcpu, struct kvm_exit_mmio *mmio,
>>  			phys_addr_t offset);
>> +void vgic_handle_base_register(struct kvm_vcpu *vcpu,
>> +			       struct kvm_exit_mmio *mmio,
>> +			       phys_addr_t offset, u64 *basereg,
>> +			       int mode);
>>  
>>  static inline
>>  u32 mmio_data_read(struct kvm_exit_mmio *mmio, u32 mask)
>>
> 