[PATCH 5/6] arm64: kvm: define PAGE_S2_DEVICE as read-only by default

[Will Deacon]

On Mon, Sep 29, 2014 at 02:06:17PM +0100, Christoffer Dall wrote:
> On Wed, Sep 17, 2014 at 02:56:20PM -0700, Ard Biesheuvel wrote:
> > Now that we support read-only memslots, we need to make sure that
> > pass-through device mappings are not mapped writable if the guest
> > has requested them to be read-only. The existing implementation
> > already honours this by calling kvm_set_s2pte_writable() on the new
> > pte in case of writable mappings, so all we need to do is define
> > the default pgprot_t value used for devices to be PTE_S2_RDONLY.
> > 
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> > ---
> >  arch/arm64/include/asm/pgtable.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> > index ffe1ba0506d1..51f6f5284ce5 100644
> > --- a/arch/arm64/include/asm/pgtable.h
> > +++ b/arch/arm64/include/asm/pgtable.h
> > @@ -79,7 +79,7 @@ extern void __pgd_error(const char *file, int line, unsigned long val);
> >  #define PAGE_HYP_DEVICE		__pgprot(PROT_DEVICE_nGnRE | PTE_HYP)
> >  
> >  #define PAGE_S2			__pgprot(PROT_DEFAULT | PTE_S2_MEMATTR(MT_S2_NORMAL) | PTE_S2_RDONLY)
> > -#define PAGE_S2_DEVICE		__pgprot(PROT_DEFAULT | PTE_S2_MEMATTR(MT_S2_DEVICE_nGnRE) | PTE_S2_RDWR | PTE_UXN)
> > +#define PAGE_S2_DEVICE		__pgprot(PROT_DEFAULT | PTE_S2_MEMATTR(MT_S2_DEVICE_nGnRE) | PTE_S2_RDONLY | PTE_UXN)
> >  
> >  #define PAGE_NONE		__pgprot(((_PAGE_DEFAULT) & ~PTE_TYPE_MASK) | PTE_PROT_NONE | PTE_PXN | PTE_UXN)
> >  #define PAGE_SHARED		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_WRITE)
> > -- 
> > 1.8.3.2
> > 
> Acked-by: Christoffer Dall <christoffer.dall at linaro.org>
> 
> Catalin, Will,
> 
> Are you fine with me queueing this through the kvmarm tree?

Fine by me.

Will