Re: [Xen-devel] [PATCH v5 22/30] ARM: vITS: handle MAPD command

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 06/04/17 00:19, Andre Przywara wrote:
> The MAPD command maps a device by associating a memory region for
> storing ITEs with a certain device ID.
> We store the given guest physical address in the device table, and, if
> this command comes from Dom0, tell the host ITS driver about this new
> mapping, so it can issue the corresponding host MAPD command and create
> the required tables.
> We simply use our existing guest memory access function to find the
> right ITT entry and store the mapping there.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
>  xen/arch/arm/vgic-v3-its.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 59 insertions(+)
>
> diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
> index bbca5cf..0372ed0 100644
> --- a/xen/arch/arm/vgic-v3-its.c
> +++ b/xen/arch/arm/vgic-v3-its.c
> @@ -42,6 +42,7 @@
>   */
>  struct virt_its {
>      struct domain *d;
> +    paddr_t doorbell_address;
>      unsigned int devid_bits;
>      unsigned int intid_bits;
>      spinlock_t vcmd_lock;       /* Protects the virtual command buffer, which 
> */
> @@ -144,6 +145,20 @@ static struct vcpu *get_vcpu_from_collection(struct 
> virt_its *its,
>  #define DEV_TABLE_ENTRY(addr, bits)                     \
>          (((addr) & GENMASK_ULL(51, 8)) | (((bits) - 1) & GENMASK_ULL(7, 0)))
>
> +/* Set the address of an ITT for a given device ID. */
> +static int its_set_itt_address(struct virt_its *its, uint32_t devid,
> +                               paddr_t itt_address, uint32_t nr_bits)
> +{
> +    paddr_t addr = get_baser_phys_addr(its->baser_dev);
> +    uint64_t itt_entry = DEV_TABLE_ENTRY(itt_address, nr_bits);
> +
> +    if ( devid >= its->max_devices )
> +        return -ENOENT;
> +
> +    return vgic_access_guest_memory(its->d, addr + devid * sizeof(uint64_t),
> +                                    &itt_entry, sizeof(itt_entry), true);
> +}
> +
>  /*
>   * Lookup the address of the Interrupt Translation Table associated with
>   * a device ID and return the address of the ITTE belonging to the event ID
> @@ -384,6 +399,47 @@ static int its_handle_mapc(struct virt_its *its, uint64_t 
> *cmdptr)
>      return 0;
>  }
>
> +static int its_handle_mapd(struct virt_its *its, uint64_t *cmdptr)
> +{
> +    /* size and devid get validated by the functions called below. */
> +    uint32_t devid = its_cmd_get_deviceid(cmdptr);
> +    unsigned int size = its_cmd_get_size(cmdptr) + 1;
> +    bool valid = its_cmd_get_validbit(cmdptr);
> +    paddr_t itt_addr = its_cmd_get_ittaddr(cmdptr);
> +    int ret;
> +
> +    /*
> +     * There is no easy and clean way for Xen to know the ITS device ID of a
> +     * particular (PCI) device, so we have to rely on the guest telling
> +     * us about it. For *now* we are just using the device ID *Dom0* uses,
> +     * because the driver there has the actual knowledge.
> +     * Eventually this will be replaced with a dedicated hypercall to
> +     * announce pass-through of devices.
> +     */
> +    if ( is_hardware_domain(its->d) )
> +    {
> +        /*
> +         * Dom0's ITSes are mapped 1:1, so both addresses are the same.
> +         * Also the device IDs are equal.
> +         */
> +        ret = gicv3_its_map_guest_device(its->d, its->doorbell_address, devid,
> +                                         its->doorbell_address, devid,
> +                                         BIT(size), valid);
> +        if ( ret )
> +            return ret;
> +    }
> +
> +    spin_lock(&its->its_lock);
> +    if ( valid )
> +        ret = its_set_itt_address(its, devid, itt_addr, size);
> +    else
> +        ret = its_set_itt_address(its, devid, INVALID_PADDR, 1);
> +
MAPD (V=0) command will also remove mapping between vLPI <-> (DeviceID, 
EventID). This means that you need to remove the irq_pending from the 
radix tree and also removing the mapping pLPI <-> vLPI.
> +    spin_unlock(&its->its_lock);
> +
> +    return ret;
> +}
> +
>  #define ITS_CMD_BUFFER_SIZE(baser)      ((((baser) & 0xff) + 1) << 12)
>
>  /*
> @@ -421,6 +477,9 @@ static int vgic_its_handle_cmds(struct domain *d, struct 
> virt_its *its)
>          case GITS_CMD_MAPC:
>              ret = its_handle_mapc(its, command);
>              break;
> +        case GITS_CMD_MAPD:
> +            ret = its_handle_mapd(its, command);
> +            break;
>          case GITS_CMD_SYNC:
>              /* We handle ITS commands synchronously, so we ignore SYNC. */
>              break;
Cheers,

--
Julien Grall

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