Re: [Xen-devel] [PATCH v5 05/30] ARM: GICv3: allocate LPI pending and property table

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 6 Apr 2017, Andre Przywara wrote:
> The ARM GICv3 provides a new kind of interrupt called LPIs.
> The pending bits and the configuration data (priority, enable bits) for
> those LPIs are stored in tables in normal memory, which software has to
> provide to the hardware.
> Allocate the required memory, initialize it and hand it over to each
> redistributor. The maximum number of LPIs to be used can be adjusted with
> the command line option "max_lpi_bits", which defaults to 20 bits,
> covering about one million LPIs.
> 
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

> ---
>  docs/misc/xen-command-line.markdown |   9 ++
>  xen/arch/arm/Makefile               |   1 +
>  xen/arch/arm/gic-v3-lpi.c           | 221 
> ++++++++++++++++++++++++++++++++++++
>  xen/arch/arm/gic-v3.c               |  17 +++
>  xen/include/asm-arm/gic_v3_defs.h   |  52 +++++++++
>  xen/include/asm-arm/gic_v3_its.h    |  15 ++-
>  xen/include/asm-arm/irq.h           |   8 ++
>  7 files changed, 322 insertions(+), 1 deletion(-)
>  create mode 100644 xen/arch/arm/gic-v3-lpi.c
> 
> diff --git a/docs/misc/xen-command-line.markdown 
> b/docs/misc/xen-command-line.markdown
> index 9eb85d6..6ef8633 100644
> --- a/docs/misc/xen-command-line.markdown
> +++ b/docs/misc/xen-command-line.markdown
> @@ -1172,6 +1172,15 @@ based interrupts. Any higher IRQs will be available 
> for use via PCI MSI.
>  ### maxcpus
>  > `= <integer>`
>  
> +### max\_lpi\_bits
> +> `= <integer>`
> +
> +Specifies the number of ARM GICv3 LPI interrupts to allocate on the host,
> +presented as the number of bits needed to encode it. This must be at least
> +14 and not exceed 32, and each LPI requires one byte (configuration) and
> +one pending bit to be allocated.
> +Defaults to 20 bits (to cover at most 1048576 interrupts).
> +
>  ### mce
>  > `= <integer>`
>  
> diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
> index 39c0a03..6be85ab 100644
> --- a/xen/arch/arm/Makefile
> +++ b/xen/arch/arm/Makefile
> @@ -19,6 +19,7 @@ obj-y += gic.o
>  obj-y += gic-v2.o
>  obj-$(CONFIG_HAS_GICV3) += gic-v3.o
>  obj-$(CONFIG_HAS_ITS) += gic-v3-its.o
> +obj-$(CONFIG_HAS_ITS) += gic-v3-lpi.o
>  obj-y += guestcopy.o
>  obj-y += hvm.o
>  obj-y += io.o
> diff --git a/xen/arch/arm/gic-v3-lpi.c b/xen/arch/arm/gic-v3-lpi.c
> new file mode 100644
> index 0000000..7f99ec6
> --- /dev/null
> +++ b/xen/arch/arm/gic-v3-lpi.c
> @@ -0,0 +1,221 @@
> +/*
> + * xen/arch/arm/gic-v3-lpi.c
> + *
> + * ARM GICv3 Locality-specific Peripheral Interrupts (LPI) support
> + *
> + * Copyright (C) 2016,2017 - ARM Ltd
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; under version 2 of the License.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <xen/lib.h>
> +#include <xen/mm.h>
> +#include <xen/sizes.h>
> +#include <xen/warning.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 LPI_PROPTABLE_NEEDS_FLUSHING    (1U << 0)
> +
> +/* Global state */
> +static struct {
> +    /* The global LPI property table, shared by all redistributors. */
> +    uint8_t *lpi_property;
> +    /*
> +     * Number of physical LPIs the host supports. This is a property of
> +     * the GIC hardware. We depart from the habit of naming these things
> +     * "physical" in Xen, as the GICv3/4 spec uses the term "physical LPI"
> +     * in a different context to differentiate them from "virtual LPIs".
> +     */
> +    unsigned long long int max_host_lpi_ids;
> +    unsigned int flags;
> +} lpi_data;
> +
> +struct lpi_redist_data {
> +    void                *pending_table;
> +};
> +
> +static DEFINE_PER_CPU(struct lpi_redist_data, lpi_redist);
> +
> +#define MAX_NR_HOST_LPIS   (lpi_data.max_host_lpi_ids - LPI_OFFSET)
> +
> +static int gicv3_lpi_allocate_pendtable(uint64_t *reg)
> +{
> +    uint64_t val;
> +    void *pendtable;
> +
> +    if ( this_cpu(lpi_redist).pending_table )
> +        return -EBUSY;
> +
> +    val  = GIC_BASER_CACHE_RaWaWb << GICR_PENDBASER_INNER_CACHEABILITY_SHIFT;
> +    val |= GIC_BASER_CACHE_SameAsInner << 
> GICR_PENDBASER_OUTER_CACHEABILITY_SHIFT;
> +    val |= GIC_BASER_InnerShareable << GICR_PENDBASER_SHAREABILITY_SHIFT;
> +
> +    /*
> +     * The pending table holds one bit per LPI and even covers bits for
> +     * interrupt IDs below 8192, so we allocate the full range.
> +     * The GICv3 imposes a 64KB alignment requirement, also requires
> +     * physically contiguous memory.
> +     */
> +    pendtable = _xzalloc(lpi_data.max_host_lpi_ids / 8, SZ_64K);
> +    if ( !pendtable )
> +        return -ENOMEM;
> +
> +    /* Make sure the physical address can be encoded in the register. */
> +    if ( virt_to_maddr(pendtable) & ~GENMASK_ULL(51, 16) )
> +    {
> +        xfree(pendtable);
> +        return -ERANGE;
> +    }
> +    clean_and_invalidate_dcache_va_range(pendtable,
> +                                         lpi_data.max_host_lpi_ids / 8);
> +
> +    this_cpu(lpi_redist).pending_table = pendtable;
> +
> +    val |= GICR_PENDBASER_PTZ;
> +
> +    val |= virt_to_maddr(pendtable);
> +
> +    *reg = val;
> +
> +    return 0;
> +}
> +
> +/*
> + * Tell a redistributor about the (shared) property table, allocating one
> + * if not already done.
> + */
> +static int gicv3_lpi_set_proptable(void __iomem * rdist_base)
> +{
> +    uint64_t reg;
> +
> +    reg  = GIC_BASER_CACHE_RaWaWb << GICR_PROPBASER_INNER_CACHEABILITY_SHIFT;
> +    reg |= GIC_BASER_CACHE_SameAsInner << 
> GICR_PROPBASER_OUTER_CACHEABILITY_SHIFT;
> +    reg |= GIC_BASER_InnerShareable << GICR_PROPBASER_SHAREABILITY_SHIFT;
> +
> +    /*
> +     * The property table is shared across all redistributors, so allocate
> +     * this only once, but return the same value on subsequent calls.
> +     */
> +    if ( !lpi_data.lpi_property )
> +    {
> +        /* The property table holds one byte per LPI. */
> +        void *table = _xmalloc(lpi_data.max_host_lpi_ids, SZ_4K);
> +
> +        if ( !table )
> +            return -ENOMEM;
> +
> +        /* Make sure the physical address can be encoded in the register. */
> +        if ( (virt_to_maddr(table) & ~GENMASK_ULL(51, 12)) )
> +        {
> +            xfree(table);
> +            return -ERANGE;
> +        }
> +        memset(table, GIC_PRI_IRQ | LPI_PROP_RES1, MAX_NR_HOST_LPIS);
> +        clean_and_invalidate_dcache_va_range(table, MAX_NR_HOST_LPIS);
> +        lpi_data.lpi_property = table;
> +    }
> +
> +    /* Encode the number of bits needed, minus one */
> +    reg |= fls(lpi_data.max_host_lpi_ids - 1) - 1;
> +
> +    reg |= virt_to_maddr(lpi_data.lpi_property);
> +
> +    writeq_relaxed(reg, rdist_base + GICR_PROPBASER);
> +    reg = readq_relaxed(rdist_base + GICR_PROPBASER);
> +
> +    /* If we can't do shareable, we have to drop cacheability as well. */
> +    if ( !(reg & GICR_PROPBASER_SHAREABILITY_MASK) )
> +    {
> +        reg &= ~GICR_PROPBASER_INNER_CACHEABILITY_MASK;
> +        reg |= GIC_BASER_CACHE_nC << GICR_PROPBASER_INNER_CACHEABILITY_SHIFT;
> +    }
> +
> +    /* Remember that we have to flush the property table if non-cacheable. */
> +    if ( (reg & GICR_PROPBASER_INNER_CACHEABILITY_MASK) <= 
> GIC_BASER_CACHE_nC )
> +    {
> +        lpi_data.flags |= LPI_PROPTABLE_NEEDS_FLUSHING;
> +        /* Update the redistributors knowledge about the attributes. */
> +        writeq_relaxed(reg, rdist_base + GICR_PROPBASER);
> +    }
> +
> +    return 0;
> +}
> +
> +int gicv3_lpi_init_rdist(void __iomem * rdist_base)
> +{
> +    uint32_t reg;
> +    uint64_t table_reg;
> +    int ret;
> +
> +    /* We don't support LPIs without an ITS. */
> +    if ( !gicv3_its_host_has_its() )
> +        return -ENODEV;
> +
> +    /* Make sure LPIs are disabled before setting up the tables. */
> +    reg = readl_relaxed(rdist_base + GICR_CTLR);
> +    if ( reg & GICR_CTLR_ENABLE_LPIS )
> +        return -EBUSY;
> +
> +    ret = gicv3_lpi_allocate_pendtable(&table_reg);
> +    if ( ret )
> +        return ret;
> +    writeq_relaxed(table_reg, rdist_base + GICR_PENDBASER);
> +    table_reg = readq_relaxed(rdist_base + GICR_PENDBASER);
> +
> +    /* If the hardware reports non-shareable, drop cacheability as well. */
> +    if ( !(table_reg & GICR_PENDBASER_SHAREABILITY_MASK) )
> +    {
> +        table_reg &= GICR_PENDBASER_SHAREABILITY_MASK;
> +        table_reg &= GICR_PENDBASER_INNER_CACHEABILITY_MASK;
> +        table_reg |= GIC_BASER_CACHE_nC << 
> GICR_PENDBASER_INNER_CACHEABILITY_SHIFT;
> +
> +        writeq_relaxed(table_reg, rdist_base + GICR_PENDBASER);
> +    }
> +
> +    return gicv3_lpi_set_proptable(rdist_base);
> +}
> +
> +static unsigned int max_lpi_bits = 20;
> +integer_param("max_lpi_bits", max_lpi_bits);
> +
> +int gicv3_lpi_init_host_lpis(unsigned int host_lpi_bits)
> +{
> +    /* An implementation needs to support at least 14 bits of LPI IDs. */
> +    max_lpi_bits = max(max_lpi_bits, 14U);
> +    lpi_data.max_host_lpi_ids = BIT_ULL(min(host_lpi_bits, max_lpi_bits));
> +
> +    /*
> +     * Warn if the number of LPIs are quite high, as the user might not want
> +     * to waste megabytes of memory for a mostly empty table.
> +     * It's very unlikely that we need more than 24 bits worth of LPIs.
> +     */
> +    if ( lpi_data.max_host_lpi_ids > BIT(24) )
> +        warning_add("Using high number of LPIs, limit memory usage with 
> max_lpi_bits\n");
> +
> +    printk("GICv3: using at most %llu LPIs on the host.\n", 
> MAX_NR_HOST_LPIS);
> +
> +    return 0;
> +}
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
> index d3d5784..54d2235 100644
> --- a/xen/arch/arm/gic-v3.c
> +++ b/xen/arch/arm/gic-v3.c
> @@ -547,6 +547,9 @@ static void __init gicv3_dist_init(void)
>      type = readl_relaxed(GICD + GICD_TYPER);
>      nr_lines = 32 * ((type & GICD_TYPE_LINES) + 1);
>  
> +    if ( type & GICD_TYPE_LPIS )
> +        gicv3_lpi_init_host_lpis(GICD_TYPE_ID_BITS(type));
> +
>      printk("GICv3: %d lines, (IID %8.8x).\n",
>             nr_lines, readl_relaxed(GICD + GICD_IIDR));
>  
> @@ -659,6 +662,20 @@ static int __init gicv3_populate_rdist(void)
>              if ( (typer >> 32) == aff )
>              {
>                  this_cpu(rbase) = ptr;
> +
> +                if ( typer & GICR_TYPER_PLPIS )
> +                {
> +                    int ret;
> +
> +                    ret = gicv3_lpi_init_rdist(ptr);
> +                    if ( ret && ret != -ENODEV )
> +                    {
> +                        printk("GICv3: CPU%d: Cannot initialize LPIs: %u\n",
> +                               smp_processor_id(), ret);
> +                        break;
> +                    }
> +                }
> +
>                  printk("GICv3: CPU%d: Found redistributor in region %d 
> @%p\n",
>                          smp_processor_id(), i, ptr);
>                  return 0;
> diff --git a/xen/include/asm-arm/gic_v3_defs.h 
> b/xen/include/asm-arm/gic_v3_defs.h
> index 6bd25a5..6f02bb0 100644
> --- a/xen/include/asm-arm/gic_v3_defs.h
> +++ b/xen/include/asm-arm/gic_v3_defs.h
> @@ -45,6 +45,9 @@
>  
>  /* Additional bits in GICD_TYPER defined by GICv3 */
>  #define GICD_TYPE_ID_BITS_SHIFT 19
> +#define GICD_TYPE_ID_BITS(r)    ((((r) >> GICD_TYPE_ID_BITS_SHIFT) & 0x1f) + 
> 1)
> +
> +#define GICD_TYPE_LPIS               (1U << 17)
>  
>  #define GICD_CTLR_RWP                (1UL << 31)
>  #define GICD_CTLR_ARE_NS             (1U << 4)
> @@ -95,12 +98,61 @@
>  #define GICR_IGRPMODR0               (0x0D00)
>  #define GICR_NSACR                   (0x0E00)
>  
> +#define GICR_CTLR_ENABLE_LPIS        (1U << 0)
> +
>  #define GICR_TYPER_PLPIS             (1U << 0)
>  #define GICR_TYPER_VLPIS             (1U << 1)
>  #define GICR_TYPER_LAST              (1U << 4)
>  
> +/* For specifying the inner cacheability type only */
> +#define GIC_BASER_CACHE_nCnB         0ULL
> +/* For specifying the outer cacheability type only */
> +#define GIC_BASER_CACHE_SameAsInner  0ULL
> +#define GIC_BASER_CACHE_nC           1ULL
> +#define GIC_BASER_CACHE_RaWt         2ULL
> +#define GIC_BASER_CACHE_RaWb         3ULL
> +#define GIC_BASER_CACHE_WaWt         4ULL
> +#define GIC_BASER_CACHE_WaWb         5ULL
> +#define GIC_BASER_CACHE_RaWaWt       6ULL
> +#define GIC_BASER_CACHE_RaWaWb       7ULL
> +#define GIC_BASER_CACHE_MASK         7ULL
> +
> +#define GIC_BASER_NonShareable       0ULL
> +#define GIC_BASER_InnerShareable     1ULL
> +#define GIC_BASER_OuterShareable     2ULL
> +
> +#define GICR_PROPBASER_OUTER_CACHEABILITY_SHIFT         56
> +#define GICR_PROPBASER_OUTER_CACHEABILITY_MASK               \
> +        (7UL << GICR_PROPBASER_OUTER_CACHEABILITY_SHIFT)
> +#define GICR_PROPBASER_SHAREABILITY_SHIFT               10
> +#define GICR_PROPBASER_SHAREABILITY_MASK                     \
> +        (3UL << GICR_PROPBASER_SHAREABILITY_SHIFT)
> +#define GICR_PROPBASER_INNER_CACHEABILITY_SHIFT         7
> +#define GICR_PROPBASER_INNER_CACHEABILITY_MASK               \
> +        (7UL << GICR_PROPBASER_INNER_CACHEABILITY_SHIFT)
> +#define GICR_PROPBASER_RES0_MASK                             \
> +        (GENMASK_ULL(63, 59) | GENMASK_ULL(55, 52) | GENMASK_ULL(6, 5))
> +
> +#define GICR_PENDBASER_SHAREABILITY_SHIFT               10
> +#define GICR_PENDBASER_INNER_CACHEABILITY_SHIFT         7
> +#define GICR_PENDBASER_OUTER_CACHEABILITY_SHIFT         56
> +#define GICR_PENDBASER_SHAREABILITY_MASK                     \
> +     (3UL << GICR_PENDBASER_SHAREABILITY_SHIFT)
> +#define GICR_PENDBASER_INNER_CACHEABILITY_MASK               \
> +     (7UL << GICR_PENDBASER_INNER_CACHEABILITY_SHIFT)
> +#define GICR_PENDBASER_OUTER_CACHEABILITY_MASK               \
> +        (7UL << GICR_PENDBASER_OUTER_CACHEABILITY_SHIFT)
> +#define GICR_PENDBASER_PTZ                              BIT(62)
> +#define GICR_PENDBASER_RES0_MASK                             \
> +        (BIT(63) | GENMASK_ULL(61, 59) | GENMASK_ULL(55, 52) |       \
> +         GENMASK_ULL(15, 12) | GENMASK_ULL(6, 0))
> +
>  #define DEFAULT_PMR_VALUE            0xff
>  
> +#define LPI_PROP_PRIO_MASK           0xfc
> +#define LPI_PROP_RES1                (1 << 1)
> +#define LPI_PROP_ENABLED             (1 << 0)
> +
>  #define GICH_VMCR_EOI                (1 << 9)
>  #define GICH_VMCR_VENG1              (1 << 1)
>  
> diff --git a/xen/include/asm-arm/gic_v3_its.h 
> b/xen/include/asm-arm/gic_v3_its.h
> index 7d88987..295eb22 100644
> --- a/xen/include/asm-arm/gic_v3_its.h
> +++ b/xen/include/asm-arm/gic_v3_its.h
> @@ -76,7 +76,10 @@ void gicv3_its_dt_init(const struct dt_device_node *node);
>  
>  bool gicv3_its_host_has_its(void);
>  
> -/* Initialize the host structures for the host ITSes. */
> +int gicv3_lpi_init_rdist(void __iomem * rdist_base);
> +
> +/* Initialize the host structures for LPIs and the host ITSes. */
> +int gicv3_lpi_init_host_lpis(unsigned int host_lpi_bits);
>  int gicv3_its_init(void);
>  
>  #else
> @@ -92,6 +95,16 @@ static inline bool gicv3_its_host_has_its(void)
>      return false;
>  }
>  
> +static inline int gicv3_lpi_init_rdist(void __iomem * rdist_base)
> +{
> +    return -ENODEV;
> +}
> +
> +static inline int gicv3_lpi_init_host_lpis(unsigned int host_lpi_bits)
> +{
> +    return 0;
> +}
> +
>  static inline int gicv3_its_init(void)
>  {
>      return 0;
> diff --git a/xen/include/asm-arm/irq.h b/xen/include/asm-arm/irq.h
> index 4849f16..f940092 100644
> --- a/xen/include/asm-arm/irq.h
> +++ b/xen/include/asm-arm/irq.h
> @@ -18,8 +18,16 @@ struct arch_irq_desc {
>  };
>  
>  #define NR_LOCAL_IRQS        32
> +
> +/*
> + * This only covers the interrupts that Xen cares about, so SGIs, PPIs and
> + * SPIs. LPIs are too numerous, also only propagated to guests, so they are
> + * not included in this number.
> + */
>  #define NR_IRQS              1024
>  
> +#define LPI_OFFSET      8192
> +
>  #define nr_irqs NR_IRQS
>  #define nr_static_irqs NR_IRQS
>  #define arch_hwdom_irqs(domid) NR_IRQS
> -- 
> 2.8.2
> 

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