RE: [PATCH v4 1/1] x86/ioremap: Fix page aligned size calculation in __ioremap_caller()

[Michael Kelley (LINUX)]

From: Wei Liu <wei.liu@xxxxxxxxxx> Sent: Friday, November 25, 2022 7:20 AM
> 
> On Tue, Nov 22, 2022 at 09:40:42AM -0800, Michael Kelley wrote:
> > Current code re-calculates the size after aligning the starting and
> > ending physical addresses on a page boundary. But the re-calculation
> > also embeds the masking of high order bits that exceed the size of
> > the physical address space (via PHYSICAL_PAGE_MASK). If the masking
> > removes any high order bits, the size calculation results in a huge
> > value that is likely to immediately fail.
> >
> > Fix this by re-calculating the page-aligned size first. Then mask any
> > high order bits using PHYSICAL_PAGE_MASK.
> >
> > Fixes: ffa71f33a820 ("x86, ioremap: Fix incorrect physical address handling in PAE mode")
> > Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> > Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> 
> Reviewed-by: Wei Liu <wei.liu@xxxxxxxxxx>
> 
> > ---
> >
> > This patch was previously Patch 1 of a larger series[1].  Breaking
> > it out separately per discussion with Dave Hansen and Boris Petkov.
> >
> > [1] https://lore.kernel.org/linux-hyperv/1668624097-14884-1-git-send-email-mikelley@xxxxxxxxxxxxx/
> >

Boris -- you were going to pick up this patch separately
though urgent.  Can you go ahead and do that?

https://lore.kernel.org/linux-hyperv/Y3vo5drAFPQSsrF4@xxxxxxx/

Michael

> >  arch/x86/mm/ioremap.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> > index 78c5bc6..6453fba 100644
> > --- a/arch/x86/mm/ioremap.c
> > +++ b/arch/x86/mm/ioremap.c
> > @@ -217,9 +217,15 @@ static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
> >  	 * Mappings have to be page-aligned
> >  	 */
> >  	offset = phys_addr & ~PAGE_MASK;
> > -	phys_addr &= PHYSICAL_PAGE_MASK;
> > +	phys_addr &= PAGE_MASK;
> >  	size = PAGE_ALIGN(last_addr+1) - phys_addr;
> >
> > +	/*
> > +	 * Mask out any bits not part of the actual physical
> > +	 * address, like memory encryption bits.
> > +	 */
> > +	phys_addr &= PHYSICAL_PAGE_MASK;
> > +
> >  	retval = memtype_reserve(phys_addr, (u64)phys_addr + size,
> >  						pcm, &new_pcm);
> >  	if (retval) {
> > --
> > 1.8.3.1
> >