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Re: [Xen-devel] [v8][PATCH 03/17] introduce XENMEM_reserved_device_memory_map



On Mon, Dec 01, 2014 at 05:24:21PM +0800, Tiejun Chen wrote:
> From: Jan Beulich <jbeulich@xxxxxxxx>
> 
> This is a prerequisite for punching holes into HVM and PVH guests' P2M
> to allow passing through devices that are associated with (on VT-d)
> RMRRs.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> ---
>  xen/common/compat/memory.c           | 54 
> ++++++++++++++++++++++++++++++++++++
>  xen/common/memory.c                  | 51 ++++++++++++++++++++++++++++++++++
>  xen/drivers/passthrough/iommu.c      | 10 +++++++
>  xen/drivers/passthrough/vtd/dmar.c   | 17 ++++++++++++
>  xen/drivers/passthrough/vtd/extern.h |  1 +
>  xen/drivers/passthrough/vtd/iommu.c  |  1 +
>  xen/include/public/memory.h          | 24 +++++++++++++++-
>  xen/include/xen/iommu.h              |  4 +++
>  xen/include/xlat.lst                 |  3 +-
>  9 files changed, 163 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/common/compat/memory.c b/xen/common/compat/memory.c
> index 06c90be..60512fa 100644
> --- a/xen/common/compat/memory.c
> +++ b/xen/common/compat/memory.c
> @@ -16,6 +16,37 @@ CHECK_TYPE(domid);
>  
>  CHECK_mem_access_op;
>  
> +#ifdef HAS_PASSTHROUGH
> +struct get_reserved_device_memory {
> +    struct compat_reserved_device_memory_map map;
> +    unsigned int used_entries;
> +};
> +
> +static int get_reserved_device_memory(xen_pfn_t start,
> +                                      xen_ulong_t nr, void *ctxt)
> +{
> +    struct get_reserved_device_memory *grdm = ctxt;
> +
> +    if ( grdm->used_entries < grdm->map.nr_entries )
> +    {
> +        struct compat_reserved_device_memory rdm = {
> +            .start_pfn = start, .nr_pages = nr
> +        };
> +
> +        if ( rdm.start_pfn != start || rdm.nr_pages != nr )
> +            return -ERANGE;
> +
> +        if ( __copy_to_compat_offset(grdm->map.buffer, grdm->used_entries,
> +                                     &rdm, 1) )
> +            return -EFAULT;
> +    }
> +
> +    ++grdm->used_entries;
> +
> +    return 0;
> +}
> +#endif
> +
>  int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat)
>  {
>      int split, op = cmd & MEMOP_CMD_MASK;
> @@ -273,6 +304,29 @@ int compat_memory_op(unsigned int cmd, 
> XEN_GUEST_HANDLE_PARAM(void) compat)
>              break;
>          }
>  
> +#ifdef HAS_PASSTHROUGH
> +        case XENMEM_reserved_device_memory_map:
> +        {
> +            struct get_reserved_device_memory grdm;
> +
> +            if ( copy_from_guest(&grdm.map, compat, 1) ||
> +                 !compat_handle_okay(grdm.map.buffer, grdm.map.nr_entries) )
> +                return -EFAULT;
> +
> +            grdm.used_entries = 0;
> +            rc = iommu_get_reserved_device_memory(get_reserved_device_memory,
> +                                                  &grdm);
> +
> +            if ( !rc && grdm.map.nr_entries < grdm.used_entries )
> +                rc = -ENOBUFS;
> +            grdm.map.nr_entries = grdm.used_entries;
> +            if ( __copy_to_guest(compat, &grdm.map, 1) )
> +                rc = -EFAULT;
> +
> +            return rc;
> +        }
> +#endif
> +
>          default:
>              return compat_arch_memory_op(cmd, compat);
>          }
> diff --git a/xen/common/memory.c b/xen/common/memory.c
> index 9f21bd3..4788acc 100644
> --- a/xen/common/memory.c
> +++ b/xen/common/memory.c
> @@ -692,6 +692,34 @@ out:
>      return rc;
>  }
>  
> +#ifdef HAS_PASSTHROUGH
> +struct get_reserved_device_memory {
> +    struct xen_reserved_device_memory_map map;
> +    unsigned int used_entries;
> +};
> +
> +static int get_reserved_device_memory(xen_pfn_t start,
> +                                      xen_ulong_t nr, void *ctxt)
> +{
> +    struct get_reserved_device_memory *grdm = ctxt;
> +
> +    if ( grdm->used_entries < grdm->map.nr_entries )
> +    {
> +        struct xen_reserved_device_memory rdm = {
> +            .start_pfn = start, .nr_pages = nr
> +        };
> +
> +        if ( __copy_to_guest_offset(grdm->map.buffer, grdm->used_entries,
> +                                    &rdm, 1) )
> +            return -EFAULT;
> +    }
> +
> +    ++grdm->used_entries;
> +
> +    return 0;
> +}
> +#endif
> +
>  long do_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
>  {
>      struct domain *d;
> @@ -1101,6 +1129,29 @@ long do_memory_op(unsigned long cmd, 
> XEN_GUEST_HANDLE_PARAM(void) arg)
>          break;
>      }
>  
> +#ifdef HAS_PASSTHROUGH
> +    case XENMEM_reserved_device_memory_map:
> +    {
> +        struct get_reserved_device_memory grdm;
> +
> +        if ( copy_from_guest(&grdm.map, arg, 1) ||
> +             !guest_handle_okay(grdm.map.buffer, grdm.map.nr_entries) )
> +            return -EFAULT;
> +

Shouldn't there be an XSM check here?

> +        grdm.used_entries = 0;
> +        rc = iommu_get_reserved_device_memory(get_reserved_device_memory,
> +                                              &grdm);
> +

Also since we doing an iteration over possible many nr_entries should
we think about returning -EAGAIN to user-space so that it can retry?
(As in, have preemption baked in this hypercall)

> +        if ( !rc && grdm.map.nr_entries < grdm.used_entries )
> +            rc = -ENOBUFS;
> +        grdm.map.nr_entries = grdm.used_entries;
> +        if ( __copy_to_guest(arg, &grdm.map, 1) )
> +            rc = -EFAULT;
> +
> +        break;
> +    }
> +#endif
> +
>      default:
>          rc = arch_memory_op(cmd, arg);
>          break;
> diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
> index cc12735..7c17e8d 100644
> --- a/xen/drivers/passthrough/iommu.c
> +++ b/xen/drivers/passthrough/iommu.c
> @@ -344,6 +344,16 @@ void iommu_crash_shutdown(void)
>      iommu_enabled = iommu_intremap = 0;
>  }
>  
> +int iommu_get_reserved_device_memory(iommu_grdm_t *func, void *ctxt)
> +{
> +    const struct iommu_ops *ops = iommu_get_ops();
> +
> +    if ( !iommu_enabled || !ops->get_reserved_device_memory )
> +        return 0;
> +
> +    return ops->get_reserved_device_memory(func, ctxt);
> +}
> +
>  bool_t iommu_has_feature(struct domain *d, enum iommu_feature feature)
>  {
>      const struct hvm_iommu *hd = domain_hvm_iommu(d);
> diff --git a/xen/drivers/passthrough/vtd/dmar.c 
> b/xen/drivers/passthrough/vtd/dmar.c
> index 5e41e7a..86cfad3 100644
> --- a/xen/drivers/passthrough/vtd/dmar.c
> +++ b/xen/drivers/passthrough/vtd/dmar.c
> @@ -901,3 +901,20 @@ int platform_supports_x2apic(void)
>      unsigned int mask = ACPI_DMAR_INTR_REMAP | ACPI_DMAR_X2APIC_OPT_OUT;
>      return cpu_has_x2apic && ((dmar_flags & mask) == ACPI_DMAR_INTR_REMAP);
>  }
> +
> +int intel_iommu_get_reserved_device_memory(iommu_grdm_t *func, void *ctxt)
> +{
> +    struct acpi_rmrr_unit *rmrr;
> +    int rc = 0;
> +
> +    list_for_each_entry(rmrr, &acpi_rmrr_units, list)
> +    {
> +        rc = func(PFN_DOWN(rmrr->base_address),
> +                  PFN_UP(rmrr->end_address) - PFN_DOWN(rmrr->base_address),
> +                  ctxt);
> +        if ( rc )
> +            break;
> +    }
> +
> +    return rc;
> +}
> diff --git a/xen/drivers/passthrough/vtd/extern.h 
> b/xen/drivers/passthrough/vtd/extern.h
> index 5524dba..f9ee9b0 100644
> --- a/xen/drivers/passthrough/vtd/extern.h
> +++ b/xen/drivers/passthrough/vtd/extern.h
> @@ -75,6 +75,7 @@ int domain_context_mapping_one(struct domain *domain, 
> struct iommu *iommu,
>                                 u8 bus, u8 devfn, const struct pci_dev *);
>  int domain_context_unmap_one(struct domain *domain, struct iommu *iommu,
>                               u8 bus, u8 devfn);
> +int intel_iommu_get_reserved_device_memory(iommu_grdm_t *func, void *ctxt);
>  
>  unsigned int io_apic_read_remap_rte(unsigned int apic, unsigned int reg);
>  void io_apic_write_remap_rte(unsigned int apic,
> diff --git a/xen/drivers/passthrough/vtd/iommu.c 
> b/xen/drivers/passthrough/vtd/iommu.c
> index 19d8165..a38f201 100644
> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -2491,6 +2491,7 @@ const struct iommu_ops intel_iommu_ops = {
>      .crash_shutdown = vtd_crash_shutdown,
>      .iotlb_flush = intel_iommu_iotlb_flush,
>      .iotlb_flush_all = intel_iommu_iotlb_flush_all,
> +    .get_reserved_device_memory = intel_iommu_get_reserved_device_memory,
>      .dump_p2m_table = vtd_dump_p2m_table,
>  };
>  
> diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
> index 595f953..cee4535 100644
> --- a/xen/include/public/memory.h
> +++ b/xen/include/public/memory.h
> @@ -572,7 +572,29 @@ struct xen_vnuma_topology_info {
>  typedef struct xen_vnuma_topology_info xen_vnuma_topology_info_t;
>  DEFINE_XEN_GUEST_HANDLE(xen_vnuma_topology_info_t);
>  
> -/* Next available subop number is 27 */
> +/*
> + * For legacy reasons, some devices must be configured with special memory
> + * regions to function correctly.  The guest must avoid using any of these
> + * regions.
> + */
> +#define XENMEM_reserved_device_memory_map   27
> +struct xen_reserved_device_memory {
> +    xen_pfn_t start_pfn;
> +    xen_ulong_t nr_pages;
> +};
> +typedef struct xen_reserved_device_memory xen_reserved_device_memory_t;
> +DEFINE_XEN_GUEST_HANDLE(xen_reserved_device_memory_t);
> +
> +struct xen_reserved_device_memory_map {
> +    /* IN/OUT */
> +    unsigned int nr_entries;
> +    /* OUT */
> +    XEN_GUEST_HANDLE(xen_reserved_device_memory_t) buffer;
> +};
> +typedef struct xen_reserved_device_memory_map 
> xen_reserved_device_memory_map_t;
> +DEFINE_XEN_GUEST_HANDLE(xen_reserved_device_memory_map_t);
> +
> +/* Next available subop number is 28 */
>  
>  #endif /* __XEN_PUBLIC_MEMORY_H__ */
>  
> diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
> index 8eb764a..409f6f8 100644
> --- a/xen/include/xen/iommu.h
> +++ b/xen/include/xen/iommu.h
> @@ -120,6 +120,8 @@ void iommu_dt_domain_destroy(struct domain *d);
>  
>  struct page_info;
>  
> +typedef int iommu_grdm_t(xen_pfn_t start, xen_ulong_t nr, void *ctxt);
> +
>  struct iommu_ops {
>      int (*init)(struct domain *d);
>      void (*hwdom_init)(struct domain *d);
> @@ -156,12 +158,14 @@ struct iommu_ops {
>      void (*crash_shutdown)(void);
>      void (*iotlb_flush)(struct domain *d, unsigned long gfn, unsigned int 
> page_count);
>      void (*iotlb_flush_all)(struct domain *d);
> +    int (*get_reserved_device_memory)(iommu_grdm_t *, void *);
>      void (*dump_p2m_table)(struct domain *d);
>  };
>  
>  void iommu_suspend(void);
>  void iommu_resume(void);
>  void iommu_crash_shutdown(void);
> +int iommu_get_reserved_device_memory(iommu_grdm_t *, void *);
>  
>  void iommu_share_p2m_table(struct domain *d);
>  
> diff --git a/xen/include/xlat.lst b/xen/include/xlat.lst
> index 41b3e35..42229fd 100644
> --- a/xen/include/xlat.lst
> +++ b/xen/include/xlat.lst
> @@ -61,9 +61,10 @@
>  !    memory_exchange                 memory.h
>  !    memory_map                      memory.h
>  !    memory_reservation              memory.h
> -?    mem_access_op           memory.h
> +?    mem_access_op                   memory.h
>  !    pod_target                      memory.h
>  !    remove_from_physmap             memory.h
> +!    reserved_device_memory_map      memory.h
>  ?    physdev_eoi                     physdev.h
>  ?    physdev_get_free_pirq           physdev.h
>  ?    physdev_irq                     physdev.h
> -- 
> 1.9.1
> 

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