Re: [Xen-devel] [PATCH] xen: arm: remove unnecessary cache flush in write_pte

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-07-29 at 16:12 +0100, Tim Deegan wrote:
> At 15:57 +0100 on 29 Jul (1375113450), Ian Campbell wrote:
> > ping?
> > 
> > On Wed, 2013-07-17 at 12:19 +0100, Ian Campbell wrote:
> > > On a ARMv7/v8 SMP system the MMU is coherent
> > > 
> > > Suggested-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> > > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > > ---
> > >  xen/include/asm-arm/arm32/page.h |    2 --
> > >  xen/include/asm-arm/arm64/page.h |    2 --
> > >  2 files changed, 0 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/xen/include/asm-arm/arm32/page.h 
> > > b/xen/include/asm-arm/arm32/page.h
> > > index 38bcffd..3a06a22 100644
> > > --- a/xen/include/asm-arm/arm32/page.h
> > > +++ b/xen/include/asm-arm/arm32/page.h
> > > @@ -16,8 +16,6 @@ static inline void write_pte(lpae_t *p, lpae_t pte)
> > >          /* Safely write the entry (STRD is atomic on CPUs that support 
> > > LPAE) */
> > >          "strd %0, %H0, [%1];"
> > >          "dsb;"
> > > -        /* Push this cacheline to the PoC so the rest of the system sees 
> > > it. */
> > > -        STORE_CP32(1, DCCMVAC)
> > >          /* Ensure that the data flush is completed before proceeding */
> > >          "dsb;"
> 
> We should drop this DSB and its comment too (likewise for the second
> 'dsb sy' below).

True, thanks.

> With that change, Acked-by: Tim Deegan <tim@xxxxxxx>.

Cheers.




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