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SubjectRe: [PATCH] powerpc/powernv: Initialise nest mmu
On Mon, Aug 15, 2016 at 04:51:59PM +1000, Alistair Popple wrote:
> POWER9 contains an off core mmu called the nest mmu (NMMU). This is
> used by other hardware units on the chip to translate virtual
> addresses into real addresses. The unit attempting an address
> translation provides the majority of the context required for the
> translation request except for the base address of the partition table
> (ie. the PTCR) which needs to be programmed into the NMMU.
>
> This patch adds a call to OPAL to set the PTCR for the nest mmu in
> opal_init().
>
> Signed-off-by: Alistair Popple <alistair@popple.id.au>
> ---
>
> This patch depends on a new OPAL call which has yet to be added to
> skiboot, although the patch to do so has been posted to
> http://patchwork.ozlabs.org/patch/659106/
>
> arch/powerpc/include/asm/opal-api.h | 3 ++-
> arch/powerpc/include/asm/opal.h | 1 +
> arch/powerpc/platforms/powernv/opal-wrappers.S | 1 +
> arch/powerpc/platforms/powernv/opal.c | 3 +++
> 4 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
> index 0e2e57b..a0aa285 100644
> --- a/arch/powerpc/include/asm/opal-api.h
> +++ b/arch/powerpc/include/asm/opal-api.h
> @@ -167,7 +167,8 @@
> #define OPAL_INT_EOI 124
> #define OPAL_INT_SET_MFRR 125
> #define OPAL_PCI_TCE_KILL 126
> -#define OPAL_LAST 126
> +#define OPAL_NMMU_SET_PTCR 127
> +#define OPAL_LAST 127
>
> /* Device tree flags */
>
> diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
> index ee05bd2..433df5e 100644
> --- a/arch/powerpc/include/asm/opal.h
> +++ b/arch/powerpc/include/asm/opal.h
> @@ -228,6 +228,7 @@ int64_t opal_pci_tce_kill(uint64_t phb_id, uint32_t kill_type,
> int64_t opal_rm_pci_tce_kill(uint64_t phb_id, uint32_t kill_type,
> uint32_t pe_num, uint32_t tce_size,
> uint64_t dma_addr, uint32_t npages);
> +int64_t opal_nmmu_set_ptcr(uint64_t chip_id, uint64_t ptcr);
>
> /* Internal functions */
> extern int early_init_dt_scan_opal(unsigned long node, const char *uname,
> diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
> index 3d29d40..a955649 100644
> --- a/arch/powerpc/platforms/powernv/opal-wrappers.S
> +++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
> @@ -308,3 +308,4 @@ OPAL_CALL(opal_int_eoi, OPAL_INT_EOI);
> OPAL_CALL(opal_int_set_mfrr, OPAL_INT_SET_MFRR);
> OPAL_CALL(opal_pci_tce_kill, OPAL_PCI_TCE_KILL);
> OPAL_CALL_REAL(opal_rm_pci_tce_kill, OPAL_PCI_TCE_KILL);
> +OPAL_CALL(opal_nmmu_set_ptcr, OPAL_NMMU_SET_PTCR);
> diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
> index 8b4fc68..b533245 100644
> --- a/arch/powerpc/platforms/powernv/opal.c
> +++ b/arch/powerpc/platforms/powernv/opal.c
> @@ -762,6 +762,9 @@ static int __init opal_init(void)
> /* Initialise OPAL kmsg dumper for flushing console on panic */
> opal_kmsg_init();
>
> + /* Update partition table control register on all Nest MMUs */
> + opal_nmmu_set_ptcr(-1UL, __pa(partition_tb) | (PATB_SIZE_SHIFT - 12));
> +

Just wondering if

1. Instead of using -1 for all cpus, we should do
for_each_online_cpu() {
opal_numm_set_ptcr(...)
}

2. In cpu hotplug path do the same when onlining and set to NULL on
offlining?

I think we should definitely try and become hotplug aware from the OS
view point and drive it from the OS

What do you think?

Balbir Singh.

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