Re: [PATCH v3 5/8] hw/intc: GICv3 ITS Feature enablement

[Peter Maydell]

On Fri, 30 Apr 2021 at 00:42, Shashi Mallela <shashi.mallela@linaro.org> wrote:
>
> Added properties to enable ITS feature and define qemu system
> address space memory in gicv3 common,setup distributor and
> redistributor registers to indicate LPI support.
>
> Signed-off-by: Shashi Mallela <shashi.mallela@linaro.org>
> ---
>  hw/intc/arm_gicv3_common.c         | 13 +++++++++++++
>  hw/intc/arm_gicv3_dist.c           | 21 +++++++++++++++++++--
>  hw/intc/arm_gicv3_redist.c         | 30 +++++++++++++++++++++++++-----
>  hw/intc/gicv3_internal.h           | 17 +++++++++++++++++
>  include/hw/intc/arm_gicv3_common.h |  1 +
>  5 files changed, 75 insertions(+), 7 deletions(-)
>
> diff --git a/hw/intc/arm_gicv3_common.c b/hw/intc/arm_gicv3_common.c
> index 58ef65f589..a55e91071a 100644
> --- a/hw/intc/arm_gicv3_common.c
> +++ b/hw/intc/arm_gicv3_common.c
> @@ -381,6 +381,16 @@ static void arm_gicv3_common_realize(DeviceState *dev, 
> Error **errp)
>              (1 << 24) |
>              (i << 8) |
>              (last << 4);
> +
> +        if (s->lpi_enable) {
> +            s->cpu[i].gicr_typer |= GICR_TYPER_PLPIS;
> +
> +            if (!s->dma) {
> +                error_setg(errp,
> +                    "Redist-ITS: Guest 'sysmem' reference link not set");
> +                return;
> +            }
> +        }

Can you put the "if (s->lpi_enable && !s->dma)" error-exit further
up in the function with all the other error-checks, please? That way
we do all our error-handling before we start allocating memory and
doing other things.

>      }
>  }
>
> @@ -494,9 +504,12 @@ static Property arm_gicv3_common_properties[] = {
>      DEFINE_PROP_UINT32("num-cpu", GICv3State, num_cpu, 1),
>      DEFINE_PROP_UINT32("num-irq", GICv3State, num_irq, 32),
>      DEFINE_PROP_UINT32("revision", GICv3State, revision, 3),
> +    DEFINE_PROP_BOOL("has-lpi", GICv3State, lpi_enable, 0),
>      DEFINE_PROP_BOOL("has-security-extensions", GICv3State, security_extn, 
> 0),
>      DEFINE_PROP_ARRAY("redist-region-count", GICv3State, nb_redist_regions,
>                        redist_region_count, qdev_prop_uint32, uint32_t),
> +    DEFINE_PROP_LINK("sysmem", GICv3State, dma, TYPE_MEMORY_REGION,
> +                     MemoryRegion *),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>
> diff --git a/hw/intc/arm_gicv3_dist.c b/hw/intc/arm_gicv3_dist.c
> index b65f56f903..43e0ea4367 100644
> --- a/hw/intc/arm_gicv3_dist.c
> +++ b/hw/intc/arm_gicv3_dist.c
> @@ -366,12 +366,15 @@ static MemTxResult gicd_readl(GICv3State *s, hwaddr 
> offset,
>          return MEMTX_OK;
>      case GICD_TYPER:
>      {
> +        bool lpi_supported = false;
>          /* For this implementation:
>           * No1N == 1 (1-of-N SPI interrupts not supported)
>           * A3V == 1 (non-zero values of Affinity level 3 supported)
>           * IDbits == 0xf (we support 16-bit interrupt identifiers)
>           * DVIS == 0 (Direct virtual LPI injection not supported)
> -         * LPIS == 0 (LPIs not supported)
> +         * LPIS == 1 (LPIs are supported if affinity routing is enabled)
> +         * num_LPIs == 0b00000 (bits [15:11],Number of LPIs as indicated
> +         *                      by GICD_TYPER.IDbits)
>           * MBIS == 0 (message-based SPIs not supported)
>           * SecurityExtn == 1 if security extns supported
>           * CPUNumber == 0 since for us ARE is always 1
> @@ -385,8 +388,22 @@ static MemTxResult gicd_readl(GICv3State *s, hwaddr 
> offset,
>           */
>          bool sec_extn = !(s->gicd_ctlr & GICD_CTLR_DS);
>
> +        /*
> +         * With securityextn on, LPIs are supported when affinity routing
> +         * is enabled for non-secure state and if off LPIs are supported
> +         * when affinity routing is enabled.
> +         */
> +        if (s->lpi_enable) {
> +            if (sec_extn) {
> +                lpi_supported = (s->gicd_ctlr & GICD_CTLR_ARE_NS);
> +            } else {
> +                lpi_supported = (s->gicd_ctlr & GICD_CTLR_ARE);
> +            }
> +        }

For our implementation, affinity routing is always enabled, so you
don't need to make a distinction between s->lpi_enable and
lpi_supported.

> +
>          *data = (1 << 25) | (1 << 24) | (sec_extn << 10) |
> -            (0xf << 19) | itlinesnumber;
> +            (lpi_supported << GICD_TYPER_LPIS_OFFSET) | (GICD_TYPER_IDBITS <<
> +            GICD_TYPER_IDBITS_OFFSET) | itlinesnumber;

Don't break the line after << like this, please; it's much easier to read
if you break after '|' instead, because then the (...) bracketed
expression stays on one line rather than being split.

>          return MEMTX_OK;
>      }
>      case GICD_IIDR:
> diff --git a/hw/intc/arm_gicv3_redist.c b/hw/intc/arm_gicv3_redist.c
> index 8645220d61..7604ccdc83 100644
> --- a/hw/intc/arm_gicv3_redist.c
> +++ b/hw/intc/arm_gicv3_redist.c
> @@ -244,14 +244,22 @@ static MemTxResult gicr_readl(GICv3CPUState *cs, hwaddr 
> offset,
>  static MemTxResult gicr_writel(GICv3CPUState *cs, hwaddr offset,
>                                 uint64_t value, MemTxAttrs attrs)
>  {
> +    uint64_t data;
> +
>      switch (offset) {
>      case GICR_CTLR:
>          /* For our implementation, GICR_TYPER.DPGS is 0 and so all
>           * the DPG bits are RAZ/WI. We don't do anything asynchronously,
> -         * so UWP and RWP are RAZ/WI. And GICR_TYPER.LPIS is 0 (we don't
> -         * implement LPIs) so Enable_LPIs is RES0. So there are no writable
> -         * bits for us.
> +         * so UWP and RWP are RAZ/WI. GICR_TYPER.LPIS is 1 (we
> +         * implement LPIs) so Enable_LPIs is programmable.
>           */
> +        if (cs->gicr_typer & GICR_TYPER_PLPIS) {
> +            if (value & GICR_CTLR_ENABLE_LPIS) {
> +                cs->gicr_ctlr |= GICR_CTLR_ENABLE_LPIS;
> +            } else {
> +                cs->gicr_ctlr &= ~GICR_CTLR_ENABLE_LPIS;
> +            }
> +        }
>          return MEMTX_OK;
>      case GICR_STATUSR:
>          /* RAZ/WI for our implementation */
> @@ -275,7 +283,12 @@ static MemTxResult gicr_writel(GICv3CPUState *cs, hwaddr 
> offset,
>          cs->gicr_waker = value;
>          return MEMTX_OK;
>      case GICR_PROPBASER:
> -        cs->gicr_propbaser = deposit64(cs->gicr_propbaser, 0, 32, value);
> +        data = value;
> +        if (FIELD_EX64(data, GICR_PROPBASER, IDBITS) > GICD_TYPER_IDBITS) {
> +            data &= ~R_GICR_PROPBASER_IDBITS_MASK;
> +            data |= GICD_TYPER_IDBITS;
> +        }
> +        cs->gicr_propbaser = deposit64(cs->gicr_propbaser, 0, 32, data);

This is still wrong. On v2 I said:

# This isn't what the spec says happens. It says that if the value the
guest writes
# in this field is larger than GICD_TYPER.IDbits, then the
GICD_TYPER.IDBits value
# applies. That doesn't mean the value reads back as GICD_TYPER.IDBits.
#
# How you want to handle this depends on what's going on, but it probably mostly
# looks like "code that cares about GICR_PROPBASER.IDBits will do
# MIN(field_value, GICD_TYPER_IDBITS) to find the effective value of the field".

>          return MEMTX_OK;
>      case GICR_PROPBASER + 4:
>          cs->gicr_propbaser = deposit64(cs->gicr_propbaser, 32, 32, value);
> @@ -395,9 +408,16 @@ static MemTxResult gicr_readll(GICv3CPUState *cs, hwaddr 
> offset,
>  static MemTxResult gicr_writell(GICv3CPUState *cs, hwaddr offset,
>                                  uint64_t value, MemTxAttrs attrs)
>  {
> +    uint64_t data;
> +
>      switch (offset) {
>      case GICR_PROPBASER:
> -        cs->gicr_propbaser = value;
> +        data = value;
> +        if (FIELD_EX64(data, GICR_PROPBASER, IDBITS) > GICD_TYPER_IDBITS) {
> +            data &= ~R_GICR_PROPBASER_IDBITS_MASK;
> +            data |= GICD_TYPER_IDBITS;
> +        }
> +        cs->gicr_propbaser = data;

Ditto.

thanks
-- PMM