Re: [PATCH for-5.0 v5 02/23] ppc/xive: Introduce helpers for the NVT id

[Greg Kurz <groug@kaod.org>]

On Fri, 15 Nov 2019 17:24:15 +0100
Cédric Le Goater <clg@kaod.org> wrote:

> Each vCPU in the system is identified with an NVT identifier which is
> pushed in the OS CAM line (QW1W2) of the HW thread interrupt context
> register when the vCPU is dispatched on a HW thread. This identifier
> is used by the presenter subengine to find a matching target to notify
> of an event. It is also used to fetch the associate NVT structure
> which may contain pending interrupts that need a resend.
> 
> Add a couple of helpers for the NVT ids. The NVT space is 19 bits
> wide, giving a maximum of 512K per chip.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  include/hw/ppc/xive.h      |  5 -----
>  include/hw/ppc/xive_regs.h | 21 +++++++++++++++++++++
>  2 files changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h
> index 8fd439ec9bba..fa7adf87feb2 100644
> --- a/include/hw/ppc/xive.h
> +++ b/include/hw/ppc/xive.h
> @@ -418,11 +418,6 @@ Object *xive_tctx_create(Object *cpu, XiveRouter *xrtr, Error **errp);
>  void xive_tctx_reset(XiveTCTX *tctx);
>  void xive_tctx_destroy(XiveTCTX *tctx);
>  
> -static inline uint32_t xive_nvt_cam_line(uint8_t nvt_blk, uint32_t nvt_idx)
> -{
> -    return (nvt_blk << 19) | nvt_idx;
> -}
> -
>  /*
>   * KVM XIVE device helpers
>   */
> diff --git a/include/hw/ppc/xive_regs.h b/include/hw/ppc/xive_regs.h
> index 530f232b04f8..1a5622f8ded8 100644
> --- a/include/hw/ppc/xive_regs.h
> +++ b/include/hw/ppc/xive_regs.h
> @@ -272,4 +272,25 @@ typedef struct XiveNVT {
>  
>  #define xive_nvt_is_valid(nvt)    (be32_to_cpu((nvt)->w0) & NVT_W0_VALID)
>  
> +/*
> + * The VP number space in a block is defined by the END_W6_NVT_INDEX
> + * field of the XIVE END
> + */
> +#define XIVE_NVT_SHIFT                19
> +
> +static inline uint32_t xive_nvt_cam_line(uint8_t nvt_blk, uint32_t nvt_idx)
> +{
> +    return (nvt_blk << XIVE_NVT_SHIFT) | nvt_idx;

Shouldn't we ensure nvt_idx fits in the 19 bits ?

> +}
> +
> +static inline uint32_t xive_nvt_idx(uint32_t cam_line)
> +{
> +    return cam_line & ((1 << XIVE_NVT_SHIFT) - 1);
> +}
> +
> +static inline uint32_t xive_nvt_blk(uint32_t cam_line)
> +{
> +    return (cam_line >> XIVE_NVT_SHIFT) & 0xf;
> +}
> +
>  #endif /* PPC_XIVE_REGS_H */