Re: [Xen-devel] [PATCH v2 21/27] ARM: vITS: handle MOVI command

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 03/16/2017 11:20 AM, Andre Przywara wrote:
> The MOVI command moves the interrupt affinity from one redistributor
> (read: VCPU) to another.
> For now migration of "live" LPIs is not yet implemented, but we store
> the changed affinity in the host LPI structure and in our virtual ITTE.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
>  xen/arch/arm/gic-v3-its.c        | 15 +++++++++++++++
>  xen/arch/arm/gic-v3-lpi.c        | 13 +++++++++++++
>  xen/arch/arm/vgic-v3-its.c       | 24 ++++++++++++++++++++++++
>  xen/include/asm-arm/gic_v3_its.h |  4 ++++
>  4 files changed, 56 insertions(+)
>
> diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
> index e2fcf50..aa9b1b2 100644
> --- a/xen/arch/arm/gic-v3-its.c
> +++ b/xen/arch/arm/gic-v3-its.c
> @@ -787,6 +787,21 @@ int gicv3_assign_guest_event(struct domain *d, paddr_t 
> doorbell_address,
>      return 0;
>  }
>
> +/* Changes the target VCPU for a given host LPI assigned to a domain. */
> +int gicv3_lpi_change_vcpu(struct domain *d, paddr_t doorbell,
> +                          uint32_t devid, uint32_t eventid,
> +                          unsigned int vcpu_id)
> +{
> +    uint32_t host_lpi = translate_event(d, doorbell, devid, eventid);
> +
> +    if ( !host_lpi )
> +        return -ENOENT;
> +
> +    gicv3_lpi_update_host_vcpuid(host_lpi, vcpu_id);
> +
> +    return 0;
> +}
> +
>  /* 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)
>  {
> diff --git a/xen/arch/arm/gic-v3-lpi.c b/xen/arch/arm/gic-v3-lpi.c
> index c110ec9..8c7cea1 100644
> --- a/xen/arch/arm/gic-v3-lpi.c
> +++ b/xen/arch/arm/gic-v3-lpi.c
> @@ -171,6 +171,19 @@ int gicv3_lpi_update_host_entry(uint32_t host_lpi, int 
> domain_id,
>      return 0;
>  }
>
> +int gicv3_lpi_update_host_vcpuid(uint32_t host_lpi, unsigned int vcpu_id)
> +{
> +    union host_lpi *hlpip;
> +
> +    host_lpi -= LPI_OFFSET;
> +
> +    hlpip = &lpi_data.host_lpis[host_lpi / HOST_LPIS_PER_PAGE][host_lpi % 
> HOST_LPIS_PER_PAGE];
> +
> +    write_u16_atomic(&hlpip->vcpu_id, vcpu_id);
> +
> +    return 0;
> +}
> +
>  static int gicv3_lpi_allocate_pendtable(uint64_t *reg)
>  {
>      uint64_t val;
> diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
> index 600ff69..bb573de 100644
> --- a/xen/arch/arm/vgic-v3-its.c
> +++ b/xen/arch/arm/vgic-v3-its.c
> @@ -351,6 +351,24 @@ static int its_handle_mapti(struct virt_its *its, uint64_t 
> *cmdptr)
>      return 0;
>  }
>
> +static int its_handle_movi(struct virt_its *its, uint64_t *cmdptr)
> +{
> +    uint32_t devid = its_cmd_get_deviceid(cmdptr);
> +    uint32_t eventid = its_cmd_get_id(cmdptr);
> +    int collid = its_cmd_get_collection(cmdptr);
> +    struct vcpu *vcpu;
> +
> +    if ( !write_itte(its, devid, eventid, collid, SKIP_LPI_UPDATE, &vcpu) )
> +        return -1;
> +
> +    /* TODO: lookup currently-in-guest virtual IRQs and migrate them */
Looking at the code, you record the vcpuID which means that the next LPI 
will be direct to this vCPU. However, the previous LPI may still be 
inflight on a different vCPU.
How the guest will behave in this case?

> +
> +    gicv3_lpi_change_vcpu(its->d,
> +                          its->doorbell_address, devid, eventid, 
> vcpu->vcpu_id);
> +
> +    return 0;
> +}
> +
>  #define ITS_CMD_BUFFER_SIZE(baser)      ((((baser) & 0xff) + 1) << 12)
>
>  static int vgic_its_handle_cmds(struct domain *d, struct virt_its *its,
> @@ -387,6 +405,12 @@ static int vgic_its_handle_cmds(struct domain *d, struct 
> virt_its *its,
>          case GITS_CMD_MAPTI:
>              its_handle_mapti(its, cmdptr);
>              break;
> +        case GITS_CMD_MOVALL:
> +            gdprintk(XENLOG_G_INFO, "ITS: ignoring MOVALL command\n");
Why MOVALL is not implemented?

> +            break;
> +        case GITS_CMD_MOVI:
> +            its_handle_movi(its, cmdptr);
> +            break;
>          case GITS_CMD_SYNC:
>              /* We handle ITS commands synchronously, so we ignore SYNC. */
>             break;
> diff --git a/xen/include/asm-arm/gic_v3_its.h b/xen/include/asm-arm/gic_v3_its.h
> index 1ea00e9..25b6b3c 100644
> --- a/xen/include/asm-arm/gic_v3_its.h
> +++ b/xen/include/asm-arm/gic_v3_its.h
> @@ -166,8 +166,12 @@ int gicv3_free_host_lpi_block(struct host_its *its, 
> uint32_t lpi);
>  int gicv3_assign_guest_event(struct domain *d, paddr_t doorbell,
>                               uint32_t devid, uint32_t eventid,
>                               struct vcpu *v, uint32_t virt_lpi);
> +int gicv3_lpi_change_vcpu(struct domain *d, paddr_t doorbell,
> +                          uint32_t devid, uint32_t eventid,
> +                          unsigned int vcpu_id);
>  int gicv3_lpi_update_host_entry(uint32_t host_lpi, int domain_id,
>                                  unsigned int vcpu_id, uint32_t virt_lpi);
> +int gicv3_lpi_update_host_vcpuid(uint32_t host_lpi, unsigned int vcpu_id);
>
>  #else
Cheers,

--
Julien Grall

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