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Re: [Xen-devel] [PATCH v5 15/30] ARM: vGICv3: handle virtual LPI pending and property tables



On Thu, 6 Apr 2017, Andre Przywara wrote:
> Allow a guest to provide the address and size for the memory regions
> it has reserved for the GICv3 pending and property tables.
> We sanitise the various fields of the respective redistributor
> registers and map those pages into Xen's address space to have easy
> access.
> This introduces a function to read and write from and to guest memory,
> to be later able to access the tables located there.
> This vgic_access_guest_memory() function has been written by Vijaya Kumar
> as part of an earlier series.
> 
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
>  xen/arch/arm/vgic-v3.c       | 152 
> ++++++++++++++++++++++++++++++++++++++-----
>  xen/arch/arm/vgic.c          |  39 +++++++++++
>  xen/include/asm-arm/domain.h |   6 +-
>  xen/include/asm-arm/vgic.h   |   3 +
>  4 files changed, 182 insertions(+), 18 deletions(-)
> 
> diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
> index 2a14305..0623803 100644
> --- a/xen/arch/arm/vgic-v3.c
> +++ b/xen/arch/arm/vgic-v3.c
> @@ -19,12 +19,14 @@
>   */
>  
>  #include <xen/bitops.h>
> +#include <xen/domain_page.h>
>  #include <xen/lib.h>
>  #include <xen/init.h>
>  #include <xen/softirq.h>
>  #include <xen/irq.h>
>  #include <xen/sched.h>
>  #include <xen/sizes.h>
> +#include <xen/vmap.h>
>  #include <asm/current.h>
>  #include <asm/mmio.h>
>  #include <asm/gic_v3_defs.h>
> @@ -228,12 +230,21 @@ static int __vgic_v3_rdistr_rd_mmio_read(struct vcpu 
> *v, mmio_info_t *info,
>          goto read_reserved;
>  
>      case VREG64(GICR_PROPBASER):
> -        /* LPI's not implemented */
> -        goto read_as_zero_64;
> +        if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
> +
> +        spin_lock(&v->arch.vgic.lock);
> +        *r = vgic_reg64_extract(v->domain->arch.vgic.rdist_propbase, info);
> +        spin_unlock(&v->arch.vgic.lock);
> +        return 1;
>  
>      case VREG64(GICR_PENDBASER):
> -        /* LPI's not implemented */
> -        goto read_as_zero_64;
> +        if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
> +
> +        spin_lock(&v->arch.vgic.lock);
> +        *r = vgic_reg64_extract(v->arch.vgic.rdist_pendbase, info);
> +        *r &= ~GICR_PENDBASER_PTZ;       /* WO, reads as 0 */
> +        spin_unlock(&v->arch.vgic.lock);
> +        return 1;
>  
>      case 0x0080:
>          goto read_reserved;
> @@ -301,11 +312,6 @@ bad_width:
>      domain_crash_synchronous();
>      return 0;
>  
> -read_as_zero_64:
> -    if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
> -    *r = 0;
> -    return 1;
> -
>  read_as_zero_32:
>      if ( dabt.size != DABT_WORD ) goto bad_width;
>      *r = 0;
> @@ -330,11 +336,95 @@ read_unknown:
>      return 1;
>  }
>  
> +static uint64_t vgic_sanitise_field(uint64_t reg, uint64_t field_mask,
> +                                    int field_shift,
> +                                    uint64_t (*sanitise_fn)(uint64_t))
> +{
> +    uint64_t field = (reg & field_mask) >> field_shift;
> +
> +    field = sanitise_fn(field) << field_shift;
> +
> +    return (reg & ~field_mask) | field;
> +}
> +
> +/* We want to avoid outer shareable. */
> +static uint64_t vgic_sanitise_shareability(uint64_t field)
> +{
> +    switch ( field )
> +    {
> +    case GIC_BASER_OuterShareable:
> +        return GIC_BASER_InnerShareable;
> +    default:
> +        return field;
> +    }
> +}
> +
> +/* Avoid any inner non-cacheable mapping. */
> +static uint64_t vgic_sanitise_inner_cacheability(uint64_t 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. */
> +static uint64_t vgic_sanitise_outer_cacheability(uint64_t field)
> +{
> +    switch ( field )
> +    {
> +    case GIC_BASER_CACHE_SameAsInner:
> +    case GIC_BASER_CACHE_nC:
> +        return field;
> +    default:
> +        return GIC_BASER_CACHE_nC;
> +    }
> +}
> +
> +static uint64_t sanitize_propbaser(uint64_t 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 &= ~GICR_PROPBASER_RES0_MASK;
> +
> +    return reg;
> +}
> +
> +static uint64_t sanitize_pendbaser(uint64_t 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 &= ~GICR_PENDBASER_RES0_MASK;
> +
> +    return reg;
> +}
> +
>  static int __vgic_v3_rdistr_rd_mmio_write(struct vcpu *v, mmio_info_t *info,
>                                            uint32_t gicr_reg,
>                                            register_t r)
>  {
>      struct hsr_dabt dabt = info->dabt;
> +    uint64_t reg;
>  
>      switch ( gicr_reg )
>      {
> @@ -365,36 +455,64 @@ static int __vgic_v3_rdistr_rd_mmio_write(struct vcpu 
> *v, mmio_info_t *info,
>          goto write_impl_defined;
>  
>      case VREG64(GICR_SETLPIR):
> -        /* LPI is not implemented */
> +        /* LPIs without an ITS are not implemented */
>          goto write_ignore_64;
>  
>      case VREG64(GICR_CLRLPIR):
> -        /* LPI is not implemented */
> +        /* LPIs without an ITS are not implemented */
>          goto write_ignore_64;
>  
>      case 0x0050:
>          goto write_reserved;
>  
>      case VREG64(GICR_PROPBASER):
> -        /* LPI is not implemented */
> -        goto write_ignore_64;
> +        if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
> +
> +        spin_lock(&v->arch.vgic.lock);
> +
> +        /* Writing PROPBASER with LPIs enabled is UNPREDICTABLE. */
> +        if ( !(v->arch.vgic.flags & VGIC_V3_LPIS_ENABLED) )
> +        {
> +            reg = v->domain->arch.vgic.rdist_propbase;
> +            vgic_reg64_update(&reg, r, info);
> +            reg = sanitize_propbaser(reg);
> +            v->domain->arch.vgic.rdist_propbase = reg;
> +        }
> +
> +        spin_unlock(&v->arch.vgic.lock);
> +
> +        return 1;
>  
>      case VREG64(GICR_PENDBASER):
> -        /* LPI is not implemented */
> -        goto write_ignore_64;
> +        if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
> +
> +        spin_lock(&v->arch.vgic.lock);
> +
> +        /* Writing PENDBASER with LPIs enabled is UNPREDICTABLE. */
> +        if ( !(v->arch.vgic.flags & VGIC_V3_LPIS_ENABLED) )
> +        {
> +            reg = v->arch.vgic.rdist_pendbase;
> +            vgic_reg64_update(&reg, r, info);
> +            reg = sanitize_pendbaser(reg);
> +            v->arch.vgic.rdist_pendbase = reg;
> +        }
> +
> +        spin_unlock(&v->arch.vgic.lock);
> +
> +        return 1;
>  
>      case 0x0080:
>          goto write_reserved;
>  
>      case VREG64(GICR_INVLPIR):
> -        /* LPI is not implemented */
> +        /* LPIs without an ITS are not implemented */
>          goto write_ignore_64;
>  
>      case 0x00A8:
>          goto write_reserved;
>  
>      case VREG64(GICR_INVALLR):
> -        /* LPI is not implemented */
> +        /* LPIs without an ITS are not implemented */
>          goto write_ignore_64;
>  
>      case 0x00B8:
> diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
> index cd9a2a5..9b0dc3d 100644
> --- a/xen/arch/arm/vgic.c
> +++ b/xen/arch/arm/vgic.c
> @@ -20,6 +20,7 @@
>  #include <xen/bitops.h>
>  #include <xen/lib.h>
>  #include <xen/init.h>
> +#include <xen/domain_page.h>
>  #include <xen/softirq.h>
>  #include <xen/irq.h>
>  #include <xen/sched.h>
> @@ -589,6 +590,44 @@ void vgic_free_virq(struct domain *d, unsigned int virq)
>      clear_bit(virq, d->arch.vgic.allocated_irqs);
>  }
>  
> +int vgic_access_guest_memory(struct domain *d, paddr_t gpa, void *addr,
> +                             uint32_t size, bool_t is_write)

Because there are no callers of this function, I think it breaks the
build.


> +{
> +    struct page_info *page;
> +    uint64_t offset;
> +    p2m_type_t p2mt;
> +    void *p;
> +
> +    page = get_page_from_gfn(d, paddr_to_pfn(gpa), &p2mt, P2M_ALLOC);
> +    if ( !page )
> +    {
> +        printk(XENLOG_G_ERR "d%d: vITS: Failed to get table entry\n",
> +               d->domain_id);
> +        return -EINVAL;
> +    }
> +
> +    if ( !p2m_is_ram(p2mt) )
> +    {
> +        put_page(page);
> +        printk(XENLOG_G_ERR "d%d: vITS: with wrong attributes\n", 
> d->domain_id);
> +        return -EINVAL;
> +    }
> +
> +    p = __map_domain_page(page);
> +    /* Offset within the mapped page */
> +    offset = gpa & ~PAGE_MASK;
> +
> +    if ( is_write )
> +        memcpy(p + offset, addr, size);
> +    else
> +        memcpy(addr, p + offset, size);
> +
> +    unmap_domain_page(p);
> +    put_page(page);
> +
> +    return 0;
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 6ee7538..f993292 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -109,6 +109,8 @@ struct arch_domain
>          } *rdist_regions;
>          int nr_regions;                     /* Number of rdist regions */
>          uint32_t rdist_stride;              /* Re-Distributor stride */
> +        unsigned long long int nr_lpis;
> +        uint64_t rdist_propbase;
>          struct rb_root its_devices;         /* Devices mapped to an ITS */
>          spinlock_t its_devices_lock;        /* Protects the its_devices tree 
> */
>          struct radix_tree_root pend_lpi_tree; /* Stores struct pending_irq's 
> */
> @@ -256,7 +258,9 @@ struct arch_vcpu
>  
>          /* GICv3: redistributor base and flags for this vCPU */
>          paddr_t rdist_base;
> -#define VGIC_V3_RDIST_LAST  (1 << 0)        /* last vCPU of the rdist */
> +        uint64_t rdist_pendbase;
> +#define VGIC_V3_RDIST_LAST      (1 << 0)        /* last vCPU of the rdist */
> +#define VGIC_V3_LPIS_ENABLED    (1 << 1)
>          uint8_t flags;
>      } vgic;
>  
> diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h
> index 08d6294..2371960 100644
> --- a/xen/include/asm-arm/vgic.h
> +++ b/xen/include/asm-arm/vgic.h
> @@ -314,6 +314,9 @@ extern void register_vgic_ops(struct domain *d, const 
> struct vgic_ops *ops);
>  int vgic_v2_init(struct domain *d, int *mmio_count);
>  int vgic_v3_init(struct domain *d, int *mmio_count);
>  
> +int vgic_access_guest_memory(struct domain *d, paddr_t gpa, void *addr,
> +                             uint32_t size, bool_t is_write);
> +
>  extern int domain_vgic_register(struct domain *d, int *mmio_count);
>  extern int vcpu_vgic_free(struct vcpu *v);
>  extern bool vgic_to_sgi(struct vcpu *v, register_t sgir,
> -- 
> 2.8.2
> 

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