Re: [PATCH 6/7] acpi, apei, ghes: Make unmapping functionality independent from architecture.

[Tomasz Nowicki]

On 13.05.2014 22:11, Borislav Petkov wrote:
> On Wed, Apr 09, 2014 at 05:14:34PM +0200, Tomasz Nowicki wrote:
> > Till now __flush_tlb_one was used for unmapping virtual memory which
> > is x86 specific function. Replace it with more generic
> > flush_tlb_kernel_range.
> >
> > Signed-off-by: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
> > ---
> >   drivers/acpi/apei/ghes.c |    4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> > index aaf8db3..624878b 100644
> > --- a/drivers/acpi/apei/ghes.c
> > +++ b/drivers/acpi/apei/ghes.c
> > @@ -185,7 +185,7 @@ static void ghes_iounmap_nmi(void __iomem *vaddr_ptr)
> >
> >   	BUG_ON(vaddr != (unsigned long)GHES_IOREMAP_NMI_PAGE(base));
> >   	unmap_kernel_range_noflush(vaddr, PAGE_SIZE);
> > -	__flush_tlb_one(vaddr);
> > +	flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
> >   }
> >
> >   static void ghes_iounmap_irq(void __iomem *vaddr_ptr)
> > @@ -195,7 +195,7 @@ static void ghes_iounmap_irq(void __iomem *vaddr_ptr)
> >
> >   	BUG_ON(vaddr != (unsigned long)GHES_IOREMAP_IRQ_PAGE(base));
> >   	unmap_kernel_range_noflush(vaddr, PAGE_SIZE);
> > -	__flush_tlb_one(vaddr);
> > +	flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
>
> flush_tlb_kernel_range() does send an IPI to every core on x86 which is
> much more expensive than what __flush_tlb_one does.
>
> Fairer it would be if you added a __flush_tlb_one() version for arm
> which does flush_tlb_kernel_range for you.

Thanks for comment. I am not sure if maintainers will allow me to add 
sth like __flush_tlb_one() for arm/arm64. Let me ask them directly. 
Catalin, Russell what do you think?

Regards,
Tomasz
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