[Skiboot] [PATCH] phb4/5: Escalate page-level TCE kills

[Stewart Smith]

Sounds like also for stable?

Sent from my iPhone

> On Aug 25, 2021, at 8:09 AM, Frederic Barrat <fbarrat at linux.ibm.com> wrote:
> 
> An hw issue was found on P10 (HW560152) where a page-level TCE kill
> can be dropped if there are enough TCE kill requests already being
> processed. The net effect is that data integrity is not
> guaranteed. The circumvention is to stay away from page-level kills
> and escalate those to PE kills. Which hurts performance.
> It also affects P9.
> 
> Signed-off-by: Frederic Barrat <fbarrat at linux.ibm.com>
> ---
> hw/phb4.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
> 
> diff --git a/hw/phb4.c b/hw/phb4.c
> index 79083d4a..ddaa18f8 100644
> --- a/hw/phb4.c
> +++ b/hw/phb4.c
> @@ -1051,6 +1051,14 @@ static int64_t phb4_tce_kill(struct phb *phb, uint32_t kill_type,
>    uint64_t val;
>    int64_t rc;
> 
> +    /*
> +     * HW560152: a page-level kill can be dropped if the
> +     *     processing queue is backed-up, which can cause data
> +     *     integrity issues
> +     */
> +    if (kill_type == OPAL_PCI_TCE_KILL_PAGES)
> +        kill_type = OPAL_PCI_TCE_KILL_PE;
> +
>    sync();
>    switch(kill_type) {
>    case OPAL_PCI_TCE_KILL_PAGES:
> -- 
> 2.31.1
> 
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