Re: [PATCH 33/55] KVM: arm64: vgic: Handle ITS related GICv3 redistributor registers

Christoffer Dall
2016-08-01T18:20:52Z

On Fri, Jul 22, 2016 at 06:28:50PM +0100, Marc Zyngier wrote:
> From: Andre Przywara <andre.przywara@arm.com>
>
> 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>
> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
> Tested-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
> include/kvm/arm_vgic.h | 13 ++++
> virt/kvm/arm/vgic/vgic-mmio-v3.c | 153 ++++++++++++++++++++++++++++++++++++++-
> virt/kvm/arm/vgic/vgic-mmio.h | 8 ++
> virt/kvm/arm/vgic/vgic-v3.c | 11 ++-
> 4 files changed, 181 insertions(+), 4 deletions(-)
>
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index 450b4da..df2dec5 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -146,6 +146,14 @@ struct vgic_dist {
> struct vgic_irq *spis;
>
> struct vgic_io_device dist_iodev;
> +
> + /*
> + * Contains the attributes and gpa 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;
> +
> + /* Contains the attributes and gpa of the LPI pending tables. */
> + 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/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> index bfcafbd..278bfbb 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 unsined long vgic_mmio_read_v3_misc(struct kvm_vcpu *vcpu,
> gpa_t addr, unsigned int len)
> {
> @@ -152,6 +165,142 @@ 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 field)
> +{
> + switch (field) {
> + case GIC_BASER_OuterShareable:
> + return GIC_BASER_InnerShareable;
> + default:
> + return field;
> + }
> +}
> +
> +/* Avoid any inner non-cacheable mapping. */
> +u64 vgic_sanitise_inner_cacheability(u64 field)
> +{
> + switch (field) {
> + case GIC_BASER_CACHE_nCnB:
> + case GIC_BASER_CACHE_nC:
> + return GIC_BASER_CACHE_RaWb;
> + default:
> + return field;
> + }
> +}
> +
> +/* Non-cacheable or same-as-inner are OK. */
> +u64 vgic_sanitise_outer_cacheability(u64 field)
> +{
> + switch (field) {
> + case GIC_BASER_CACHE_SameAsInner:
> + case GIC_BASER_CACHE_nC:
> + return field;
> + default:
> + return GIC_BASER_CACHE_nC;
> + }
> +}
> +
> +u64 vgic_sanitise_field(u64 reg, u64 field_mask, int field_shift,
> + u64 (*sanitise_fn)(u64))
> +{
> + u64 field = (reg & field_mask) >> field_shift;
> +
> + field = sanitise_fn(field) << field_shift;
> + return (reg & ~field_mask) | field;
> +}
> +
> +#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 u64 vgic_sanitise_pendbaser(u64 reg)
> +{
> + reg = vgic_sanitise_field(reg, GICR_PENDBASER_SHAREABILITY_MASK,
> + GICR_PENDBASER_SHAREABILITY_SHIFT,
> + vgic_sanitise_shareability);
> + reg = vgic_sanitise_field(reg, GICR_PENDBASER_INNER_CACHEABILITY_MASK,
> + GICR_PENDBASER_INNER_CACHEABILITY_SHIFT,
> + vgic_sanitise_inner_cacheability);
> + reg = vgic_sanitise_field(reg, GICR_PENDBASER_OUTER_CACHEABILITY_MASK,
> + GICR_PENDBASER_OUTER_CACHEABILITY_SHIFT,
> + vgic_sanitise_outer_cacheability);
> +
> + reg &= ~PENDBASER_RES0_MASK;
> + reg &= ~GENMASK_ULL(51, 48);
> +
> + return reg;
> +}
> +
> +static u64 vgic_sanitise_propbaser(u64 reg)
> +{
> + reg = vgic_sanitise_field(reg, GICR_PROPBASER_SHAREABILITY_MASK,
> + GICR_PROPBASER_SHAREABILITY_SHIFT,
> + vgic_sanitise_shareability);
> + reg = vgic_sanitise_field(reg, GICR_PROPBASER_INNER_CACHEABILITY_MASK,
> + GICR_PROPBASER_INNER_CACHEABILITY_SHIFT,
> + vgic_sanitise_inner_cacheability);
> + reg = vgic_sanitise_field(reg, GICR_PROPBASER_OUTER_CACHEABILITY_MASK,
> + GICR_PROPBASER_OUTER_CACHEABILITY_SHIFT,
> + vgic_sanitise_outer_cacheability);
> +
> + reg &= ~PROPBASER_RES0_MASK;
> + reg &= ~GENMASK_ULL(51, 48);
> + return reg;
> +}
> +
> +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;
> + u64 propbaser = dist->propbaser;
> +
> + /* Storing a value with LPIs already enabled is undefined */
> + if (vgic_cpu->lpis_enabled)
> + return;
> +
> + propbaser = update_64bit_reg(propbaser, addr & 4, len, val);
> + propbaser = vgic_sanitise_propbaser(propbaser);
> +
> + dist->propbaser = propbaser;

Which guarantees do we have that this will always be a single atomic
write?

> +}
> +
> +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;
> + u64 pendbaser = vgic_cpu->pendbaser;
> +
> + /* Storing a value with LPIs already enabled is undefined */
> + if (vgic_cpu->lpis_enabled)
> + return;
> +
> + pendbaser = update_64bit_reg(pendbaser, addr & 4, len, val);
> + pendbaser = vgic_sanitise_pendbaser(pendbaser);
> +
> + vgic_cpu->pendbaser = pendbaser;

same (assuming multiple VCPUs could be accessing this redistributor at
the same time?)

> +}
> +
> /*
> * The GICv3 per-IRQ registers are split to control PPIs and SGIs in the
> * redistributors, while SPIs are covered by registers in the distributor
> @@ -232,10 +381,10 @@ 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..71aa39d 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, u64 field_mask, int field_shift,
> + u64 (*sanitise_fn)(u64));
> +#endif
> +
> #endif
> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> index f0ac064..6f8f31f 100644
> --- a/virt/kvm/arm/vgic/vgic-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> @@ -191,6 +191,11 @@ void vgic_v3_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
> vmcrp->pmr = (vmcr & ICH_VMCR_PMR_MASK) >> ICH_VMCR_PMR_SHIFT;
> }
>
> +#define INITIAL_PENDBASER_VALUE \
> + (GIC_BASER_CACHEABILITY(GICR_PENDBASER, INNER, RaWb) | \
> + GIC_BASER_CACHEABILITY(GICR_PENDBASER, OUTER, SameAsInner) | \
> + GIC_BASER_SHAREABILITY(GICR_PENDBASER, InnerShareable))
> +
> void vgic_v3_enable(struct kvm_vcpu *vcpu)
> {
> struct vgic_v3_cpu_if *vgic_v3 = &vcpu->arch.vgic_cpu.vgic_v3;
> @@ -208,10 +213,12 @@ 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;
> + } else {
> vgic_v3->vgic_sre = 0;
> + }
>
> /* Get the show on the road... */
> vgic_v3->vgic_hcr = ICH_HCR_EN;
> --
> 2.8.1
>