On Mon, 17 Sep 2018 11:38:35 +0530
"Aneesh Kumar K.V" <aneesh.ku...@linux.ibm.com> wrote:
> Nicholas Piggin <npig...@gmail.com> writes:
>
> > The SLBIA IH=1 hint will remove all non-zero SLBEs, but only
> > invalidate ERAT entries associated with a class value of 1, for
> > processors that support the hint (e.g., POWER6 and newer), which
> > Linux assigns to user addresses.
> >
> > This prevents kernel ERAT entries from being invalidated when
> > context switchig (if the thread faulted in more than 8 user SLBEs).
>
>
> how about renaming stuff to indicate kernel ERAT entries are kept?
> something like slb_flush_and_rebolt_user()?
User mappings aren't bolted though. I consider rebolt to mean update
the bolted kernel mappings when something has changed (like vmalloc
segment update). That doesn't need to be done here, so I think this
is okay. I can add a comment though.
Thanks,
Nick
>
> >
> > Signed-off-by: Nicholas Piggin <npig...@gmail.com>
> > ---
> > arch/powerpc/mm/slb.c | 38 +++++++++++++++++++++++---------------
> > 1 file changed, 23 insertions(+), 15 deletions(-)
> >
> > diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
> > index a5e58f11d676..03fa1c663ccf 100644
> > --- a/arch/powerpc/mm/slb.c
> > +++ b/arch/powerpc/mm/slb.c
> > @@ -128,13 +128,21 @@ void slb_flush_all_realmode(void)
> > asm volatile("slbmte %0,%0; slbia" : : "r" (0));
> > }
> >
> > -static void __slb_flush_and_rebolt(void)
> > +void slb_flush_and_rebolt(void)
> > {
> > /* If you change this make sure you change SLB_NUM_BOLTED
> > * and PR KVM appropriately too. */
> > unsigned long linear_llp, lflags;
> > unsigned long ksp_esid_data, ksp_vsid_data;
> >
> > + WARN_ON(!irqs_disabled());
> > +
> > + /*
> > + * We can't take a PMU exception in the following code, so hard
> > + * disable interrupts.
> > + */
> > + hard_irq_disable();
> > +
> > linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
> > lflags = SLB_VSID_KERNEL | linear_llp;
> >
> > @@ -160,20 +168,7 @@ static void __slb_flush_and_rebolt(void)
> > :: "r"(ksp_vsid_data),
> > "r"(ksp_esid_data)
> > : "memory");
> > -}
> >
> > -void slb_flush_and_rebolt(void)
> > -{
> > -
> > - WARN_ON(!irqs_disabled());
> > -
> > - /*
> > - * We can't take a PMU exception in the following code, so hard
> > - * disable interrupts.
> > - */
> > - hard_irq_disable();
> > -
> > - __slb_flush_and_rebolt();
> > get_paca()->slb_cache_ptr = 0;
> > }
> >
> > @@ -248,7 +243,20 @@ void switch_slb(struct task_struct *tsk, struct
> > mm_struct *mm)
> >
> > asm volatile("isync" : : : "memory");
> > } else {
> > - __slb_flush_and_rebolt();
> > + struct slb_shadow *p = get_slb_shadow();
> > + unsigned long ksp_esid_data =
> > + be64_to_cpu(p->save_area[KSTACK_INDEX].esid);
> > + unsigned long ksp_vsid_data =
> > + be64_to_cpu(p->save_area[KSTACK_INDEX].vsid);
> > +
> > + asm volatile("isync\n"
> > + PPC_SLBIA(1) "\n"
> > + "slbmte %0,%1\n"
> > + "isync"
> > + :: "r"(ksp_vsid_data),
> > + "r"(ksp_esid_data));
> > +
> > + asm volatile("isync" : : : "memory");
> > }
> >
> > get_paca()->slb_cache_ptr = 0;
> > --
> > 2.18.0
>
