Re: [PATCH 08/13] ppc/xive2: Support "Pull Thread Context to Register" operation

["Cédric Le Goater" <clg@kaod.org>]

On 8/1/24 22:30, Michael Kowal wrote:
> From: Glenn Miles <milesg@linux.vnet.ibm.com>
> 
> Adds support for single byte read of offset 0x838 of the TIMA address
> space.  According to the XIVE2 Specification, this causes the hardware
> to atomically:
>    1. Read the number of bytes requested (lbz or lhz are supported).
>    2. Reset the valid bit of the thread context.
>    3. Return the number of bytes requested in step 1 to a register.
> 
> Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
> Signed-off-by: Michael Kowal <kowal@linux.ibm.com>


Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.


> ---
>   include/hw/ppc/xive_regs.h |  2 ++
>   hw/intc/xive.c             | 15 +++++++++++++++
>   2 files changed, 17 insertions(+)
> 
> diff --git a/include/hw/ppc/xive_regs.h b/include/hw/ppc/xive_regs.h
> index f8f05deafd..558a5ae742 100644
> --- a/include/hw/ppc/xive_regs.h
> +++ b/include/hw/ppc/xive_regs.h
> @@ -101,6 +101,7 @@
>   #define   TM_QW3W2_LP           PPC_BIT32(6)
>   #define   TM_QW3W2_LE           PPC_BIT32(7)
>   #define   TM_QW3W2_T            PPC_BIT32(31)
> +#define   TM_QW3B8_VT           PPC_BIT8(0)
>   
>   /*
>    * In addition to normal loads to "peek" and writes (only when invalid)
> @@ -128,6 +129,7 @@
>   #define TM_SPC_PULL_POOL_CTX    0x828   /* Load32/Load64 Pull/Invalidate Pool */
>                                           /* context to reg                     */
>   #define TM_SPC_ACK_HV_REG       0x830   /* Load16 ack HV irq to reg           */
> +#define TM_SPC_PULL_PHYS_CTX    0x838   /* Pull phys ctx to reg               */
>   #define TM_SPC_PULL_USR_CTX_OL  0xc08   /* Store8 Pull/Inval usr ctx to odd   */
>                                           /* line                               */
>   #define TM_SPC_ACK_OS_EL        0xc10   /* Store8 ack OS irq to even line     */
> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
> index 6229a6f870..5b66a3aec5 100644
> --- a/hw/intc/xive.c
> +++ b/hw/intc/xive.c
> @@ -179,6 +179,17 @@ static uint64_t xive_tm_pull_pool_ctx(XivePresenter *xptr, XiveTCTX *tctx,
>       return qw2w2;
>   }
>   
> +static uint64_t xive_tm_pull_phys_ctx(XivePresenter *xptr, XiveTCTX *tctx,
> +                                      hwaddr offset, unsigned size)
> +{
> +    uint8_t qw3b8_prev = tctx->regs[TM_QW3_HV_PHYS + TM_WORD2];
> +    uint8_t qw3b8;
> +
> +    qw3b8 = qw3b8_prev & ~TM_QW3B8_VT;
> +    tctx->regs[TM_QW3_HV_PHYS + TM_WORD2] = qw3b8;
> +    return qw3b8;
> +}
> +
>   static void xive_tm_vt_push(XivePresenter *xptr, XiveTCTX *tctx, hwaddr offset,
>                               uint64_t value, unsigned size)
>   {
> @@ -527,6 +538,8 @@ static const XiveTmOp xive_tm_operations[] = {
>                                                        xive_tm_pull_pool_ctx },
>       { XIVE_TM_HV_PAGE, TM_SPC_PULL_POOL_CTX,      8, NULL,
>                                                        xive_tm_pull_pool_ctx },
> +    { XIVE_TM_HV_PAGE, TM_SPC_PULL_PHYS_CTX,      1, NULL,
> +                                                     xive_tm_pull_phys_ctx },
>   };
>   
>   static const XiveTmOp xive2_tm_operations[] = {
> @@ -566,6 +579,8 @@ static const XiveTmOp xive2_tm_operations[] = {
>                                                        xive_tm_pull_pool_ctx },
>       { XIVE_TM_HV_PAGE, TM_SPC_PULL_OS_CTX_OL,     1, xive2_tm_pull_os_ctx_ol,
>                                                        NULL },
> +    { XIVE_TM_HV_PAGE, TM_SPC_PULL_PHYS_CTX,      1, NULL,
> +                                                     xive_tm_pull_phys_ctx },
>   };
>   
>   static const XiveTmOp *xive_tm_find_op(XivePresenter *xptr, hwaddr offset,