Re: [PATCH v7 08/17] KVM: arm64: handle ITS related GICv3 redistributor registers

[Auger Eric <eric.auger@redhat.com>]

Hi Andre,

On 28/06/2016 14:32, 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.
> We also sanitise the registers, making sure RES0 regions are respected
> and checking for valid memory attributes.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  include/kvm/vgic/vgic.h          |  13 ++++
>  virt/kvm/arm/vgic-v3.c           |  11 ++-
>  virt/kvm/arm/vgic/vgic-mmio-v3.c | 143 ++++++++++++++++++++++++++++++++++++++-
>  virt/kvm/arm/vgic/vgic-mmio.h    |   8 +++
>  4 files changed, 171 insertions(+), 4 deletions(-)
> 
> diff --git a/include/kvm/vgic/vgic.h b/include/kvm/vgic/vgic.h
> index a296d94..c56331c 100644
> --- a/include/kvm/vgic/vgic.h
> +++ b/include/kvm/vgic/vgic.h
> @@ -146,6 +146,14 @@ struct vgic_dist {
>  	struct vgic_irq		*spis;
>  
>  	struct vgic_io_device	dist_iodev;
> +
> +	/*
> +	 * Contains the address of the LPI configuration table.
> +	 * Since we report GICR_TYPER.CommonLPIAff as 0b00, we can share
> +	 * one address across all redistributors.
> +	 * GICv3 spec: 6.1.2 "LPI Configuration tables"
> +	 */
> +	u64			propbaser;
>  };
>  
>  struct vgic_v2_cpu_if {
> @@ -200,6 +208,11 @@ struct vgic_cpu {
>  	 */
>  	struct vgic_io_device	rd_iodev;
>  	struct vgic_io_device	sgi_iodev;
> +
> +	/* Points to the LPI pending tables for the redistributor */
> +	u64 pendbaser;
> +
> +	bool lpis_enabled;
>  };
>  
>  int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write);
> diff --git a/virt/kvm/arm/vgic-v3.c b/virt/kvm/arm/vgic-v3.c
> index 75b02fa..5c8b2d1 100644
> --- a/virt/kvm/arm/vgic-v3.c
> +++ b/virt/kvm/arm/vgic-v3.c
> @@ -166,6 +166,11 @@ static void vgic_v3_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
>  	vcpu->arch.vgic_cpu.vgic_v3.vgic_vmcr = vmcr;
>  }
>  
> +#define INITIAL_PENDBASER_VALUE						  \
> +	(GIC_BASER_CACHEABILITY(GICR_PENDBASER, INNER, RaWb)		| \
> +	GIC_BASER_CACHEABILITY(GICR_PENDBASER, OUTER, SameAsInner)	| \
> +	GIC_BASER_SHAREABILITY(GICR_PENDBASER, InnerShareable))
> +
>  static void vgic_v3_enable(struct kvm_vcpu *vcpu)
>  {
>  	struct vgic_v3_cpu_if *vgic_v3 = &vcpu->arch.vgic_cpu.vgic_v3;
> @@ -183,10 +188,12 @@ static void vgic_v3_enable(struct kvm_vcpu *vcpu)
>  	 * way, so we force SRE to 1 to demonstrate this to the guest.
>  	 * This goes with the spec allowing the value to be RAO/WI.
>  	 */
> -	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3)
> +	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) {
>  		vgic_v3->vgic_sre = ICC_SRE_EL1_SRE;
> -	else
> +		vcpu->arch.vgic_cpu->pendbaser = INITIAL_PENDBASER_VALUE;
this prevents the "old" VGIC from compiling.

Cheers

Eric
> +	} else {
>  		vgic_v3->vgic_sre = 0;
> +	}
>  
>  	/* Get the show on the road... */
>  	vgic_v3->vgic_hcr = ICH_HCR_EN;
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> index 829909e..7268c61 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> @@ -29,6 +29,19 @@ static unsigned long extract_bytes(unsigned long data, unsigned int offset,
>  	return (data >> (offset * 8)) & GENMASK_ULL(num * 8 - 1, 0);
>  }
>  
> +/* allows updates of any half of a 64-bit register (or the whole thing) */
> +static u64 update_64bit_reg(u64 reg, unsigned int offset, unsigned int len,
> +			    unsigned long val)
> +{
> +	int lower = (offset & 4) * 8;
> +	int upper = lower + 8 * len - 1;
> +
> +	reg &= ~GENMASK_ULL(upper, lower);
> +	val &= GENMASK_ULL(len * 8 - 1, 0);
> +
> +	return reg | ((u64)val << lower);
> +}
> +
>  static unsigned long vgic_mmio_read_v3_misc(struct kvm_vcpu *vcpu,
>  					    gpa_t addr, unsigned int len)
>  {
> @@ -150,6 +163,132 @@ static unsigned long vgic_mmio_read_v3_idregs(struct kvm_vcpu *vcpu,
>  	return 0;
>  }
>  
> +/* We want to avoid outer shareable. */
> +u64 vgic_sanitise_shareability(u64 reg)
> +{
> +	switch (reg & GIC_BASER_SHAREABILITY_MASK) {
> +	case GIC_BASER_OuterShareable:
> +		return GIC_BASER_InnerShareable;
> +	default:
> +		return reg;
> +	}
> +}
> +
> +/* Non-cacheable or same-as-inner are OK. */
> +u64 vgic_sanitise_outer_cacheability(u64 reg)
> +{
> +	switch (reg & GIC_BASER_CACHE_MASK) {
> +	case GIC_BASER_CACHE_SameAsInner:
> +	case GIC_BASER_CACHE_nC:
> +		return reg;
> +	default:
> +		return GIC_BASER_CACHE_nC;
> +	}
> +}
> +
> +/* Avoid any inner non-cacheable mapping. */
> +u64 vgic_sanitise_inner_cacheability(u64 reg)
> +{
> +	switch (reg & GIC_BASER_CACHE_MASK) {
> +	case GIC_BASER_CACHE_nCnB:
> +	case GIC_BASER_CACHE_nC:
> +		return GIC_BASER_CACHE_RaWb;
> +	default:
> +		return reg;
> +	}
> +}
> +
> +u64 vgic_sanitise_field(u64 reg, int field_shift, u64 field_mask,
> +			u64 (*sanitise_fn)(u64))
> +{
> +	u64 field = (reg >> field_shift) & field_mask;
> +
> +	field = sanitise_fn(field) << field_shift;
> +	return (reg & ~(field_mask << field_shift)) | field;
> +}
> +
> +static u64 vgic_sanitise_pendbaser(u64 reg)
> +{
> +	reg = vgic_sanitise_field(reg, GICR_PENDBASER_SHAREABILITY_SHIFT,
> +				  GIC_BASER_SHAREABILITY_MASK,
> +				  vgic_sanitise_shareability);
> +	reg = vgic_sanitise_field(reg, GICR_PENDBASER_INNER_CACHEABILITY_SHIFT,
> +				  GIC_BASER_CACHE_MASK,
> +				  vgic_sanitise_inner_cacheability);
> +	reg = vgic_sanitise_field(reg, GICR_PENDBASER_OUTER_CACHEABILITY_SHIFT,
> +				  GIC_BASER_CACHE_MASK,
> +				  vgic_sanitise_outer_cacheability);
> +	return reg;
> +}
> +
> +static u64 vgic_sanitise_propbaser(u64 reg)
> +{
> +	reg = vgic_sanitise_field(reg, GICR_PROPBASER_SHAREABILITY_SHIFT,
> +				  GIC_BASER_SHAREABILITY_MASK,
> +				  vgic_sanitise_shareability);
> +	reg = vgic_sanitise_field(reg, GICR_PROPBASER_INNER_CACHEABILITY_SHIFT,
> +				  GIC_BASER_CACHE_MASK,
> +				  vgic_sanitise_inner_cacheability);
> +	reg = vgic_sanitise_field(reg, GICR_PROPBASER_OUTER_CACHEABILITY_SHIFT,
> +				  GIC_BASER_CACHE_MASK,
> +				  vgic_sanitise_outer_cacheability);
> +	return reg;
> +}
> +
> +#define PROPBASER_RES0_MASK						\
> +	(GENMASK_ULL(63, 59) | GENMASK_ULL(55, 52) | GENMASK_ULL(6, 5))
> +#define PENDBASER_RES0_MASK						\
> +	(BIT_ULL(63) | GENMASK_ULL(61, 59) | GENMASK_ULL(55, 52) |	\
> +	 GENMASK_ULL(15, 12) | GENMASK_ULL(6, 0))
> +
> +static unsigned long vgic_mmio_read_propbase(struct kvm_vcpu *vcpu,
> +					     gpa_t addr, unsigned int len)
> +{
> +	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
> +
> +	return extract_bytes(dist->propbaser, addr & 7, len);
> +}
> +
> +static void vgic_mmio_write_propbase(struct kvm_vcpu *vcpu,
> +				     gpa_t addr, unsigned int len,
> +				     unsigned long val)
> +{
> +	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
> +	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
> +
> +	/* Storing a value with LPIs already enabled is undefined */
> +	if (vgic_cpu->lpis_enabled)
> +		return;
> +
> +	dist->propbaser = update_64bit_reg(dist->propbaser, addr & 4, len, val);
> +	dist->propbaser &= ~PROPBASER_RES0_MASK;
> +	dist->propbaser = vgic_sanitise_propbaser(dist->propbaser);
> +}
> +
> +static unsigned long vgic_mmio_read_pendbase(struct kvm_vcpu *vcpu,
> +					     gpa_t addr, unsigned int len)
> +{
> +	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
> +
> +	return extract_bytes(vgic_cpu->pendbaser, addr & 7, len);
> +}
> +
> +static void vgic_mmio_write_pendbase(struct kvm_vcpu *vcpu,
> +				     gpa_t addr, unsigned int len,
> +				     unsigned long val)
> +{
> +	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
> +
> +	/* Storing a value with LPIs already enabled is undefined */
> +	if (vgic_cpu->lpis_enabled)
> +		return;
> +
> +	vgic_cpu->pendbaser = update_64bit_reg(vgic_cpu->pendbaser,
> +					       addr & 4, len, val);
> +	vgic_cpu->pendbaser &= ~PENDBASER_RES0_MASK;
> +	vgic_cpu->pendbaser = vgic_sanitise_pendbaser(vgic_cpu->pendbaser);
> +}
> +
>  /*
>   * The GICv3 per-IRQ registers are split to control PPIs and SGIs in the
>   * redistributors, while SPIs are covered by registers in the distributor
> @@ -230,10 +369,10 @@ static const struct vgic_register_region vgic_v3_rdbase_registers[] = {
>  		vgic_mmio_read_v3r_typer, vgic_mmio_write_wi, 8,
>  		VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_LENGTH(GICR_PROPBASER,
> -		vgic_mmio_read_raz, vgic_mmio_write_wi, 8,
> +		vgic_mmio_read_propbase, vgic_mmio_write_propbase, 8,
>  		VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_LENGTH(GICR_PENDBASER,
> -		vgic_mmio_read_raz, vgic_mmio_write_wi, 8,
> +		vgic_mmio_read_pendbase, vgic_mmio_write_pendbase, 8,
>  		VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>  	REGISTER_DESC_WITH_LENGTH(GICR_IDREGS,
>  		vgic_mmio_read_v3_idregs, vgic_mmio_write_wi, 48,
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
> index 8509014..e863ccc 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.h
> +++ b/virt/kvm/arm/vgic/vgic-mmio.h
> @@ -147,4 +147,12 @@ unsigned int vgic_v2_init_dist_iodev(struct vgic_io_device *dev);
>  
>  unsigned int vgic_v3_init_dist_iodev(struct vgic_io_device *dev);
>  
> +#ifdef CONFIG_KVM_ARM_VGIC_V3
> +u64 vgic_sanitise_outer_cacheability(u64 reg);
> +u64 vgic_sanitise_inner_cacheability(u64 reg);
> +u64 vgic_sanitise_shareability(u64 reg);
> +u64 vgic_sanitise_field(u64 reg, int field_shift, u64 field_mask,
> +			u64 (*sanitise_fn)(u64));
> +#endif
> +
>  #endif
>