Re: [PATCH v3 06/26] ARM: GICv3 ITS: introduce device mapping

[Vijay Kilari <vijay.kilari@gmail.com>]

Hi Andre,

On Fri, Mar 31, 2017 at 11:35 PM, Andre Przywara <andre.przywara@arm.com> wrote:
> The ITS uses device IDs to map LPIs to a device. Dom0 will later use
> those IDs, which we directly pass on to the host.
> For this we have to map each device that Dom0 may request to a host
> ITS device with the same identifier.
> Allocate the respective memory and enter each device into an rbtree to
> later be able to iterate over it or to easily teardown guests.
>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  xen/arch/arm/gic-v3-its.c        | 227 +++++++++++++++++++++++++++++++++++++++
>  xen/arch/arm/vgic-v3.c           |   4 +
>  xen/include/asm-arm/domain.h     |   3 +
>  xen/include/asm-arm/gic_v3_its.h |  23 ++++
>  4 files changed, 257 insertions(+)
>
> diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
> index 1ac598f..295f7dc 100644
> --- a/xen/arch/arm/gic-v3-its.c
> +++ b/xen/arch/arm/gic-v3-its.c
> @@ -21,6 +21,8 @@
>  #include <xen/lib.h>
>  #include <xen/delay.h>
>  #include <xen/mm.h>
> +#include <xen/rbtree.h>
> +#include <xen/sched.h>
>  #include <xen/sizes.h>
>  #include <asm/gic.h>
>  #include <asm/gic_v3_defs.h>
> @@ -32,6 +34,18 @@
>
>  LIST_HEAD(host_its_list);
>
> +struct its_devices {
> +    struct rb_node rbnode;
> +    struct host_its *hw_its;
> +    void *itt_addr;
> +    paddr_t guest_doorbell;             /* Identifies the virtual ITS */
> +    uint32_t host_devid;
> +    uint32_t guest_devid;
> +    uint32_t eventids;                  /* Number of event IDs (MSIs) */
> +    uint32_t *host_lpi_blocks;          /* Which LPIs are used on the host */
> +    struct pending_irq *pend_irqs;      /* One struct per event */
> +};
> +
>  bool gicv3_its_host_has_its(void)
>  {
>      return !list_empty(&host_its_list);
> @@ -151,6 +165,26 @@ static int its_send_cmd_mapc(struct host_its *its, uint32_t collection_id,
>      return its_send_command(its, cmd);
>  }
>
> +static int its_send_cmd_mapd(struct host_its *its, uint32_t deviceid,
> +                             uint8_t size_bits, paddr_t itt_addr, bool valid)
> +{
> +    uint64_t cmd[4];
> +
> +    if ( valid )
> +    {
> +        ASSERT(size_bits < 32);
> +        ASSERT(!(itt_addr & ~GENMASK_ULL(51, 8)));
> +    }
> +    cmd[0] = GITS_CMD_MAPD | ((uint64_t)deviceid << 32);
> +    cmd[1] = size_bits;
> +    cmd[2] = itt_addr;
> +    if ( valid )
> +        cmd[2] |= GITS_VALID_BIT;
> +    cmd[3] = 0x00;
> +
> +    return its_send_command(its, cmd);
> +}
> +
>  /* Set up the (1:1) collection mapping for the given host CPU. */
>  int gicv3_its_setup_collection(unsigned int cpu)
>  {
> @@ -376,6 +410,7 @@ static int gicv3_its_init_single_its(struct host_its *hw_its)
>      hw_its->devid_bits = min(hw_its->devid_bits, max_its_device_bits);
>      if ( reg & GITS_TYPER_PTA )
>          hw_its->flags |= HOST_ITS_USES_PTA;
> +    hw_its->itte_size = GITS_TYPER_ITT_SIZE(reg);
>
>      for ( i = 0; i < GITS_BASER_NR_REGS; i++ )
>      {
> @@ -432,6 +467,197 @@ int gicv3_its_init(void)
>      return 0;
>  }
>
> +static int remove_mapped_guest_device(struct its_devices *dev)
> +{
> +    int ret;
> +
> +    if ( dev->hw_its )
> +    {
> +        /* MAPD also discards all events with this device ID. */
> +        int ret = its_send_cmd_mapd(dev->hw_its, dev->host_devid, 0, 0, false);
> +        if ( ret )
> +            return ret;
> +    }
> +
> +    ret = gicv3_its_wait_commands(dev->hw_its);
> +    if ( ret )
> +        return ret;
> +
> +    xfree(dev->itt_addr);
> +    xfree(dev->pend_irqs);
> +    xfree(dev);
> +
> +    return 0;
> +}
> +
> +static struct host_its *gicv3_its_find_by_doorbell(paddr_t doorbell_address)
> +{
> +    struct host_its *hw_its;
> +
> +    list_for_each_entry(hw_its, &host_its_list, entry)
> +    {
> +        if ( hw_its->addr + ITS_DOORBELL_OFFSET == doorbell_address )
> +            return hw_its;
> +    }
> +
> +    return NULL;
> +}
> +
> +static int compare_its_guest_devices(struct its_devices *dev,
> +                                     paddr_t doorbell, uint32_t devid)
> +{
> +    if ( dev->guest_doorbell < doorbell )
> +        return -1;
> +
> +    if ( dev->guest_doorbell > doorbell )
> +        return 1;
> +
> +    if ( dev->guest_devid < devid )
> +        return -1;
> +
> +    if ( dev->guest_devid > devid )
> +        return 1;
> +
> +    return 0;
> +}
> +
> +/*
> + * Map a hardware device, identified by a certain host ITS and its device ID
> + * to domain d, a guest ITS (identified by its doorbell address) and device ID.
> + * Also provide the number of events (MSIs) needed for that device.
> + * This does not check if this particular hardware device is already mapped
> + * at another domain, it is expected that this would be done by the caller.
> + */
> +int gicv3_its_map_guest_device(struct domain *d,
> +                               paddr_t host_doorbell, uint32_t host_devid,
> +                               paddr_t guest_doorbell, uint32_t guest_devid,
> +                               uint32_t nr_events, bool valid)
> +{
> +    void *itt_addr = NULL;
> +    struct host_its *hw_its;
> +    struct its_devices *dev = NULL;
> +    struct rb_node **new = &d->arch.vgic.its_devices.rb_node, *parent = NULL;
> +    int ret = -ENOENT;
> +
> +    hw_its = gicv3_its_find_by_doorbell(host_doorbell);
> +    if ( !hw_its )
> +        return ret;
> +
> +    /* check for already existing mappings */
> +    spin_lock(&d->arch.vgic.its_devices_lock);
> +    while ( *new )
> +    {
> +        struct its_devices *temp;
> +        int cmp;
> +
> +        temp = rb_entry(*new, struct its_devices, rbnode);
> +
> +        parent = *new;
> +        cmp = compare_its_guest_devices(temp, guest_doorbell, guest_devid);
> +        if ( !cmp )
> +        {
> +            if ( !valid )
> +                rb_erase(&temp->rbnode, &d->arch.vgic.its_devices);
> +
> +            spin_unlock(&d->arch.vgic.its_devices_lock);
> +
> +            if ( valid )
> +                return -EBUSY;
> +
> +            return remove_mapped_guest_device(temp);
> +        }
> +
> +        if ( cmp > 0 )
> +            new = &((*new)->rb_left);
> +        else
> +            new = &((*new)->rb_right);
> +    }
> +
> +    if ( !valid )
> +        goto out_unlock;
> +
> +    ret = -ENOMEM;
> +
> +    /* An Interrupt Translation Table needs to be 256-byte aligned. */
> +    itt_addr = _xzalloc(nr_events * hw_its->itte_size, 256);

      As I mentioned, in previous version, if itt_addr is not enough size,
ITS would overwrite and corrupt memory.
Similar to size passed in MAPD cmd, itt_addr should also be allocated of size
ROUNDUP(nr_events, LPI_BLOCK).

> +    if ( !itt_addr )
> +        goto out_unlock;
> +
> +    dev = xzalloc(struct its_devices);
> +    if ( !dev )
> +        goto out_unlock;
> +
> +    /*
> +     * Allocate the pending_irqs for each virtual LPI. They will be put
> +     * into the domain's radix tree upon the guest's MAPTI command.
> +     */
> +    dev->pend_irqs = xzalloc_array(struct pending_irq, nr_events);
> +    if ( !dev->pend_irqs )
> +        goto out_unlock;
> +
> +    ret = its_send_cmd_mapd(hw_its, host_devid,
> +                            fls(ROUNDUP(nr_events, LPI_BLOCK) - 1) - 1,
> +                            virt_to_maddr(itt_addr), true);
> +    if ( ret )
> +        goto out_unlock;
> +
> +    dev->itt_addr = itt_addr;
> +    dev->hw_its = hw_its;
> +    dev->guest_doorbell = guest_doorbell;
> +    dev->guest_devid = guest_devid;
> +    dev->host_devid = host_devid;
> +    dev->eventids = nr_events;
> +
> +    rb_link_node(&dev->rbnode, parent, new);
> +    rb_insert_color(&dev->rbnode, &d->arch.vgic.its_devices);
> +
> +    spin_unlock(&d->arch.vgic.its_devices_lock);
> +
> +    return 0;
> +
> +out_unlock:
> +    spin_unlock(&d->arch.vgic.its_devices_lock);
> +    if ( dev )
> +    {
> +        xfree(dev->pend_irqs);
> +        xfree(dev->host_lpi_blocks);
> +    }
> +    xfree(itt_addr);
> +    xfree(dev);
> +    return ret;
> +}
> +
> +/* Removing any connections a domain had to any ITS in the system. */
> +void gicv3_its_unmap_all_devices(struct domain *d)
> +{
> +    struct rb_node *victim;
> +    struct its_devices *dev;
> +
> +    /*
> +     * This is an easily readable, but suboptimal implementation.
> +     * It uses the provided iteration wrapper and erases each node, which
> +     * possibly triggers rebalancing.
> +     * This seems overkill since we are going to abolish the whole tree, but
> +     * avoids an open-coded re-implementation of the traversal functions with
> +     * some recursive function calls.
> +     */
> +restart:
> +    spin_lock(&d->arch.vgic.its_devices_lock);
> +    if ( (victim = rb_first(&d->arch.vgic.its_devices)) )
> +    {
> +        dev = rb_entry(victim, struct its_devices, rbnode);
> +        rb_erase(victim, &d->arch.vgic.its_devices);
> +
> +        spin_unlock(&d->arch.vgic.its_devices_lock);
> +
> +        remove_mapped_guest_device(dev);
> +
> +        goto restart;
> +    }
> +
> +    spin_unlock(&d->arch.vgic.its_devices_lock);
> +}
> +
>  /* Scan the DT for any ITS nodes and create a list of host ITSes out of it. */
>  void gicv3_its_dt_init(const struct dt_device_node *node)
>  {
> @@ -459,6 +685,7 @@ void gicv3_its_dt_init(const struct dt_device_node *node)
>          its_data->addr = addr;
>          its_data->size = size;
>          its_data->dt_node = its;
> +        spin_lock_init(&its_data->cmd_lock);
>
>          printk("GICv3: Found ITS @0x%lx\n", addr);
>
> diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
> index d61479d..6242252 100644
> --- a/xen/arch/arm/vgic-v3.c
> +++ b/xen/arch/arm/vgic-v3.c
> @@ -1450,6 +1450,9 @@ static int vgic_v3_domain_init(struct domain *d)
>      d->arch.vgic.nr_regions = rdist_count;
>      d->arch.vgic.rdist_regions = rdist_regions;
>
> +    spin_lock_init(&d->arch.vgic.its_devices_lock);
> +    d->arch.vgic.its_devices = RB_ROOT;
> +
>      /*
>       * Domain 0 gets the hardware address.
>       * Guests get the virtual platform layout.
> @@ -1522,6 +1525,7 @@ static int vgic_v3_domain_init(struct domain *d)
>
>  static void vgic_v3_domain_free(struct domain *d)
>  {
> +    gicv3_its_unmap_all_devices(d);
>      xfree(d->arch.vgic.rdist_regions);
>  }
>
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 2d6fbb1..e559027 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -11,6 +11,7 @@
>  #include <asm/gic.h>
>  #include <public/hvm/params.h>
>  #include <xen/serial.h>
> +#include <xen/rbtree.h>
>
>  struct hvm_domain
>  {
> @@ -109,6 +110,8 @@ struct arch_domain
>          } *rdist_regions;
>          int nr_regions;                     /* Number of rdist regions */
>          uint32_t rdist_stride;              /* Re-Distributor stride */
> +        struct rb_root its_devices;         /* Devices mapped to an ITS */
> +        spinlock_t its_devices_lock;        /* Protects the its_devices tree */
>  #endif
>      } vgic;
>
> diff --git a/xen/include/asm-arm/gic_v3_its.h b/xen/include/asm-arm/gic_v3_its.h
> index 4c2ae1c..4ade5f6 100644
> --- a/xen/include/asm-arm/gic_v3_its.h
> +++ b/xen/include/asm-arm/gic_v3_its.h
> @@ -48,6 +48,10 @@
>  #define GITS_TYPER_DEVICE_ID_BITS(r)    (((r & GITS_TYPER_DEVIDS_MASK) >> \
>                                                 GITS_TYPER_DEVIDS_SHIFT) + 1)
>  #define GITS_TYPER_IDBITS_SHIFT         8
> +#define GITS_TYPER_ITT_SIZE_SHIFT       4
> +#define GITS_TYPER_ITT_SIZE_MASK        (0xfUL << GITS_TYPER_ITT_SIZE_SHIFT)
> +#define GITS_TYPER_ITT_SIZE(r)          ((((r) & GITS_TYPER_ITT_SIZE_MASK) >> \
> +                                                GITS_TYPER_ITT_SIZE_SHIFT) + 1)
>
>  #define GITS_IIDR_VALUE                 0x34c
>
> @@ -94,7 +98,10 @@
>  #define GITS_CMD_MOVALL                 0x0e
>  #define GITS_CMD_DISCARD                0x0f
>
> +#define ITS_DOORBELL_OFFSET             0x10040
> +
>  #include <xen/device_tree.h>
> +#include <xen/rbtree.h>
>
>  #define HOST_ITS_FLUSH_CMD_QUEUE        (1U << 0)
>  #define HOST_ITS_USES_PTA               (1U << 1)
> @@ -109,6 +116,7 @@ struct host_its {
>      unsigned int devid_bits;
>      spinlock_t cmd_lock;
>      void *cmd_buf;
> +    unsigned int itte_size;
>      unsigned int flags;
>  };
>
> @@ -135,6 +143,17 @@ uint64_t gicv3_get_redist_address(unsigned int cpu, bool use_pta);
>  /* Map a collection for this host CPU to each host ITS. */
>  int gicv3_its_setup_collection(unsigned int cpu);
>
> +/*
> + * Map a device on the host by allocating an ITT on the host (ITS).
> + * "nr_event" specifies how many events (interrupts) this device will need.
> + * Setting "valid" to false deallocates the device.
> + */
> +int gicv3_its_map_guest_device(struct domain *d,
> +                               paddr_t host_doorbell, uint32_t host_devid,
> +                               paddr_t guest_doorbell, uint32_t guest_devid,
> +                               uint32_t nr_events, bool valid);
> +void gicv3_its_unmap_all_devices(struct domain *d);
> +
>  #else
>
>  static LIST_HEAD(host_its_list);
> @@ -173,6 +192,10 @@ static inline int gicv3_its_setup_collection(unsigned int cpu)
>      return 0;
>  }
>
> +static inline void gicv3_its_unmap_all_devices(struct domain *d)
> +{
> +}
> +
>  #endif /* CONFIG_HAS_ITS */
>
>  #endif
> --
> 2.9.0
>

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