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Re: [Xen-devel] [PATCH v3 05/26] ARM: GICv3 ITS: introduce ITS command handling



On Fri, 31 Mar 2017, Andre Przywara wrote:
> To be able to easily send commands to the ITS, create the respective
> wrapper functions, which take care of the ring buffer.
> The first two commands we implement provide methods to map a collection
> to a redistributor (aka host core) and to flush the command queue (SYNC).
> Start using these commands for mapping one collection to each host CPU.
> 
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>

Please address Julien's comments. In particular, cmd_lock needs to be
initialized here.


> ---
>  xen/arch/arm/gic-v3-its.c         | 182 
> ++++++++++++++++++++++++++++++++++++++
>  xen/arch/arm/gic-v3-lpi.c         |  22 +++++
>  xen/arch/arm/gic-v3.c             |  25 +++++-
>  xen/include/asm-arm/gic_v3_defs.h |   2 +
>  xen/include/asm-arm/gic_v3_its.h  |  38 ++++++++
>  5 files changed, 267 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
> index 9a86769..1ac598f 100644
> --- a/xen/arch/arm/gic-v3-its.c
> +++ b/xen/arch/arm/gic-v3-its.c
> @@ -19,11 +19,14 @@
>   */
>  
>  #include <xen/lib.h>
> +#include <xen/delay.h>
>  #include <xen/mm.h>
>  #include <xen/sizes.h>
> +#include <asm/gic.h>
>  #include <asm/gic_v3_defs.h>
>  #include <asm/gic_v3_its.h>
>  #include <asm/io.h>
> +#include <asm/page.h>
>  
>  #define ITS_CMD_QUEUE_SZ                SZ_1M
>  
> @@ -34,6 +37,147 @@ bool gicv3_its_host_has_its(void)
>      return !list_empty(&host_its_list);
>  }
>  
> +#define BUFPTR_MASK                     GENMASK_ULL(19, 5)
> +static int its_send_command(struct host_its *hw_its, const void *its_cmd)
> +{
> +    /* Some small grace period in case the command queue is congested. */
> +    s_time_t deadline = NOW() + MILLISECS(1);
> +    uint64_t readp, writep;
> +    int ret = -EBUSY;
> +
> +    /* No ITS commands from an interrupt handler (at the moment). */
> +    ASSERT(!in_irq());
> +
> +    spin_lock(&hw_its->cmd_lock);
> +
> +    do {
> +        readp = readq_relaxed(hw_its->its_base + GITS_CREADR) & BUFPTR_MASK;
> +        writep = readq_relaxed(hw_its->its_base + GITS_CWRITER) & 
> BUFPTR_MASK;
> +
> +        if ( ((writep + ITS_CMD_SIZE) % ITS_CMD_QUEUE_SZ) != readp )
> +        {
> +            ret = 0;
> +            break;
> +        }
> +
> +        /*
> +         * If the command queue is full, wait for a bit in the hope it drains
> +         * before giving up.
> +         */
> +        spin_unlock(&hw_its->cmd_lock);
> +        cpu_relax();
> +        udelay(1);
> +        spin_lock(&hw_its->cmd_lock);
> +    } while ( NOW() <= deadline );
> +
> +    if ( ret )
> +    {
> +        spin_unlock(&hw_its->cmd_lock);
> +        printk(XENLOG_WARNING "ITS: command queue full.\n");
> +        return ret;
> +    }
> +
> +    memcpy(hw_its->cmd_buf + writep, its_cmd, ITS_CMD_SIZE);
> +    if ( hw_its->flags & HOST_ITS_FLUSH_CMD_QUEUE )
> +        clean_and_invalidate_dcache_va_range(hw_its->cmd_buf + writep,
> +                                             ITS_CMD_SIZE);
> +    else
> +        dsb(ishst);
> +
> +    writep = (writep + ITS_CMD_SIZE) % ITS_CMD_QUEUE_SZ;
> +    writeq_relaxed(writep & BUFPTR_MASK, hw_its->its_base + GITS_CWRITER);
> +
> +    spin_unlock(&hw_its->cmd_lock);
> +
> +    return 0;
> +}
> +
> +/* Wait for an ITS to finish processing all commands. */
> +static int gicv3_its_wait_commands(struct host_its *hw_its)
> +{
> +    /* Define an upper limit for our wait time. */
> +    s_time_t deadline = NOW() + MILLISECS(100);
> +    uint64_t readp, writep;
> +
> +    do {
> +        spin_lock(&hw_its->cmd_lock);
> +        readp = readq_relaxed(hw_its->its_base + GITS_CREADR) & BUFPTR_MASK;
> +        writep = readq_relaxed(hw_its->its_base + GITS_CWRITER) & 
> BUFPTR_MASK;
> +        spin_unlock(&hw_its->cmd_lock);
> +
> +        if ( readp == writep )
> +            return 0;
> +
> +        cpu_relax();
> +        udelay(1);
> +    } while ( NOW() <= deadline );
> +
> +    return -ETIMEDOUT;
> +}
> +
> +static uint64_t encode_rdbase(struct host_its *hw_its, unsigned int cpu,
> +                              uint64_t reg)
> +{
> +    reg &= ~GENMASK_ULL(51, 16);
> +
> +    reg |= gicv3_get_redist_address(cpu, hw_its->flags & HOST_ITS_USES_PTA);
> +
> +    return reg;
> +}
> +
> +static int its_send_cmd_sync(struct host_its *its, unsigned int cpu)
> +{
> +    uint64_t cmd[4];
> +
> +    cmd[0] = GITS_CMD_SYNC;
> +    cmd[1] = 0x00;
> +    cmd[2] = encode_rdbase(its, cpu, 0x0);
> +    cmd[3] = 0x00;
> +
> +    return its_send_command(its, cmd);
> +}
> +
> +static int its_send_cmd_mapc(struct host_its *its, uint32_t collection_id,
> +                             unsigned int cpu)
> +{
> +    uint64_t cmd[4];
> +
> +    cmd[0] = GITS_CMD_MAPC;
> +    cmd[1] = 0x00;
> +    cmd[2] = encode_rdbase(its, cpu, collection_id);
> +    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)
> +{
> +    struct host_its *its;
> +    int ret;
> +
> +    list_for_each_entry(its, &host_its_list, entry)
> +    {
> +        if ( !its->cmd_buf )
> +            continue;
> +
> +        ret = its_send_cmd_mapc(its, cpu, cpu);
> +        if ( ret )
> +            return ret;
> +
> +        ret = its_send_cmd_sync(its, cpu);
> +        if ( ret )
> +            return ret;
> +
> +        ret = gicv3_its_wait_commands(its);
> +        if ( ret )
> +            return ret;
> +    }
> +
> +    return 0;
> +}
> +
>  #define BASER_ATTR_MASK                                           \
>          ((0x3UL << GITS_BASER_SHAREABILITY_SHIFT)               | \
>           (0x7UL << GITS_BASER_OUTER_CACHEABILITY_SHIFT)         | \
> @@ -178,6 +322,38 @@ retry:
>      return -EINVAL;
>  }
>  
> +/*
> + * Before an ITS gets initialized, it should be in a quiescent state, where
> + * all outstanding commands and transactions have finished.
> + * So if the ITS is already enabled, turn it off and wait for all outstanding
> + * operations to get processed by polling the QUIESCENT bit.
> + */
> +static int gicv3_disable_its(struct host_its *hw_its)
> +{
> +    uint32_t reg;
> +    /* A similar generous wait limit as we use for the command queue wait. */
> +    s_time_t deadline = NOW() + MILLISECS(100);
> +
> +    reg = readl_relaxed(hw_its->its_base + GITS_CTLR);
> +    if ( !(reg & GITS_CTLR_ENABLE) && (reg & GITS_CTLR_QUIESCENT) )
> +        return 0;
> +
> +    writel_relaxed(reg & ~GITS_CTLR_ENABLE, hw_its->its_base + GITS_CTLR);
> +
> +    do {
> +        reg = readl_relaxed(hw_its->its_base + GITS_CTLR);
> +        if ( reg & GITS_CTLR_QUIESCENT )
> +            return 0;
> +
> +        cpu_relax();
> +        udelay(1);
> +    } while ( NOW() <= deadline );
> +
> +    dprintk(XENLOG_ERR, "ITS not quiescent.\n");
> +
> +    return -ETIMEDOUT;
> +}
> +
>  /* Allow a user to limit the number of devices. */
>  static unsigned int max_its_device_bits = 32;
>  integer_param("max_its_device_bits", max_its_device_bits);
> @@ -191,9 +367,15 @@ static int gicv3_its_init_single_its(struct host_its 
> *hw_its)
>      if ( !hw_its->its_base )
>          return -ENOMEM;
>  
> +    ret = gicv3_disable_its(hw_its);
> +    if ( ret )
> +        return ret;
> +
>      reg = readq_relaxed(hw_its->its_base + GITS_TYPER);
>      hw_its->devid_bits = GITS_TYPER_DEVICE_ID_BITS(reg);
>      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;
>  
>      for ( i = 0; i < GITS_BASER_NR_REGS; i++ )
>      {
> diff --git a/xen/arch/arm/gic-v3-lpi.c b/xen/arch/arm/gic-v3-lpi.c
> index 77f6009..d85d63d 100644
> --- a/xen/arch/arm/gic-v3-lpi.c
> +++ b/xen/arch/arm/gic-v3-lpi.c
> @@ -43,6 +43,8 @@ static struct {
>  } lpi_data;
>  
>  struct lpi_redist_data {
> +    paddr_t             redist_addr;
> +    unsigned int        redist_id;
>      void                *pending_table;
>  };
>  
> @@ -50,6 +52,26 @@ static DEFINE_PER_CPU(struct lpi_redist_data, lpi_redist);
>  
>  #define MAX_PHYS_LPIS   (lpi_data.nr_host_lpis - LPI_OFFSET)
>  
> +/* Stores this redistributor's physical address and ID in a per-CPU variable 
> */
> +void gicv3_set_redist_address(paddr_t address, unsigned int redist_id)
> +{
> +    this_cpu(lpi_redist).redist_addr = address;
> +    this_cpu(lpi_redist).redist_id = redist_id;
> +}
> +
> +/*
> + * Returns a redistributor's ID (either as an address or as an ID).
> + * This must be (and is) called only after it has been setup by the above
> + * function.
> + */
> +uint64_t gicv3_get_redist_address(unsigned int cpu, bool use_pta)
> +{
> +    if ( use_pta )
> +        return per_cpu(lpi_redist, cpu).redist_addr & GENMASK_ULL(51, 16);
> +    else
> +        return per_cpu(lpi_redist, cpu).redist_id << 16;
> +}
> +
>  static int gicv3_lpi_allocate_pendtable(uint64_t *reg)
>  {
>      uint64_t val;
> diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
> index b84bc40..0e21cb2 100644
> --- a/xen/arch/arm/gic-v3.c
> +++ b/xen/arch/arm/gic-v3.c
> @@ -666,7 +666,21 @@ static int __init gicv3_populate_rdist(void)
>  
>                  if ( typer & GICR_TYPER_PLPIS )
>                  {
> -                    int ret;
> +                    paddr_t rdist_addr;
> +                    int procnum, ret;
> +
> +                    /*
> +                     * The ITS refers to redistributors either by their 
> physical
> +                     * address or by their ID. Determine those two values and
> +                     * let the ITS code store them in per host CPU variables 
> to
> +                     * later be able to address those redistributors.
> +                     */
> +                    rdist_addr = gicv3.rdist_regions[i].base;
> +                    rdist_addr += ptr - gicv3.rdist_regions[i].map_base;
> +                    procnum = (typer & GICR_TYPER_PROC_NUM_MASK);
> +                    procnum >>= GICR_TYPER_PROC_NUM_SHIFT;
> +
> +                    gicv3_set_redist_address(rdist_addr, procnum);
>  
>                      ret = gicv3_lpi_init_rdist(ptr);
>                      if ( ret && ret != -ENODEV )
> @@ -705,7 +719,7 @@ static int __init gicv3_populate_rdist(void)
>  
>  static int gicv3_cpu_init(void)
>  {
> -    int i;
> +    int i, ret;
>      uint32_t priority;
>  
>      /* Register ourselves with the rest of the world */
> @@ -715,6 +729,13 @@ static int gicv3_cpu_init(void)
>      if ( gicv3_enable_redist() )
>          return -ENODEV;
>  
> +    if ( gicv3_its_host_has_its() )
> +    {
> +        ret = gicv3_its_setup_collection(smp_processor_id());
> +        if ( ret )
> +            return ret;
> +    }
> +
>      /* Set priority on PPI and SGI interrupts */
>      priority = (GIC_PRI_IPI << 24 | GIC_PRI_IPI << 16 | GIC_PRI_IPI << 8 |
>                  GIC_PRI_IPI);
> diff --git a/xen/include/asm-arm/gic_v3_defs.h 
> b/xen/include/asm-arm/gic_v3_defs.h
> index 7cdebc5..b01b6ed 100644
> --- a/xen/include/asm-arm/gic_v3_defs.h
> +++ b/xen/include/asm-arm/gic_v3_defs.h
> @@ -103,6 +103,8 @@
>  #define GICR_TYPER_PLPIS             (1U << 0)
>  #define GICR_TYPER_VLPIS             (1U << 1)
>  #define GICR_TYPER_LAST              (1U << 4)
> +#define GICR_TYPER_PROC_NUM_SHIFT    8
> +#define GICR_TYPER_PROC_NUM_MASK     (0xffff << GICR_TYPER_PROC_NUM_SHIFT)
>  
>  /* For specifying the inner cacheability type only */
>  #define GIC_BASER_CACHE_nCnB         0ULL
> diff --git a/xen/include/asm-arm/gic_v3_its.h 
> b/xen/include/asm-arm/gic_v3_its.h
> index f21162a..4c2ae1c 100644
> --- a/xen/include/asm-arm/gic_v3_its.h
> +++ b/xen/include/asm-arm/gic_v3_its.h
> @@ -42,10 +42,12 @@
>  #define GITS_CTLR_QUIESCENT             BIT(31)
>  #define GITS_CTLR_ENABLE                BIT(0)
>  
> +#define GITS_TYPER_PTA                  BIT_ULL(19)
>  #define GITS_TYPER_DEVIDS_SHIFT         13
>  #define GITS_TYPER_DEVIDS_MASK          (0x1fUL << GITS_TYPER_DEVIDS_SHIFT)
>  #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_IIDR_VALUE                 0x34c
>  
> @@ -76,9 +78,26 @@
>  
>  #define GITS_CBASER_SIZE_MASK           0xff
>  
> +/* ITS command definitions */
> +#define ITS_CMD_SIZE                    32
> +
> +#define GITS_CMD_MOVI                   0x01
> +#define GITS_CMD_INT                    0x03
> +#define GITS_CMD_CLEAR                  0x04
> +#define GITS_CMD_SYNC                   0x05
> +#define GITS_CMD_MAPD                   0x08
> +#define GITS_CMD_MAPC                   0x09
> +#define GITS_CMD_MAPTI                  0x0a
> +#define GITS_CMD_MAPI                   0x0b
> +#define GITS_CMD_INV                    0x0c
> +#define GITS_CMD_INVALL                 0x0d
> +#define GITS_CMD_MOVALL                 0x0e
> +#define GITS_CMD_DISCARD                0x0f
> +
>  #include <xen/device_tree.h>
>  
>  #define HOST_ITS_FLUSH_CMD_QUEUE        (1U << 0)
> +#define HOST_ITS_USES_PTA               (1U << 1)
>  
>  /* data structure for each hardware ITS */
>  struct host_its {
> @@ -88,6 +107,7 @@ struct host_its {
>      paddr_t size;
>      void __iomem *its_base;
>      unsigned int devid_bits;
> +    spinlock_t cmd_lock;
>      void *cmd_buf;
>      unsigned int flags;
>  };
> @@ -108,6 +128,13 @@ int gicv3_lpi_init_rdist(void __iomem * rdist_base);
>  int gicv3_lpi_init_host_lpis(unsigned int nr_lpis);
>  int gicv3_its_init(void);
>  
> +/* Store the physical address and ID for each redistributor as read from DT. 
> */
> +void gicv3_set_redist_address(paddr_t address, unsigned int redist_id);
> +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);
> +
>  #else
>  
>  static LIST_HEAD(host_its_list);
> @@ -135,6 +162,17 @@ static inline int gicv3_its_init(void)
>  {
>      return 0;
>  }
> +
> +static inline void gicv3_set_redist_address(paddr_t address,
> +                                            unsigned int redist_id)
> +{
> +}
> +
> +static inline int gicv3_its_setup_collection(unsigned int cpu)
> +{
> +    return 0;
> +}
> +
>  #endif /* CONFIG_HAS_ITS */
>  
>  #endif
> -- 
> 2.9.0
> 

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