[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 09/22] xen/arm: p2m: Use a whitelist rather than blacklist in get_page_from_gfn
On Wed, 27 Jul 2016, Julien Grall wrote: > On 26/07/16 23:44, Stefano Stabellini wrote: > > On Wed, 20 Jul 2016, Julien Grall wrote: > > > Currently, the check in get_page_from_gfn is using a blacklist. This is > > > very fragile because we may forgot to update the check when a new p2m > > > type is added. > > > > > > To avoid any possible issue, use a whitelist. All type backed by a RAM > > > page can could potential be valid. The check is borrowed from x86. > > > > > > Signed-off-by: Julien Grall <julien.grall@xxxxxxx> > > > --- > > > xen/include/asm-arm/p2m.h | 9 ++++++++- > > > 1 file changed, 8 insertions(+), 1 deletion(-) > > > > > > diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h > > > index 3091c04..78d37ab 100644 > > > --- a/xen/include/asm-arm/p2m.h > > > +++ b/xen/include/asm-arm/p2m.h > > > @@ -104,9 +104,16 @@ typedef enum { > > > #define P2M_RAM_TYPES (p2m_to_mask(p2m_ram_rw) | \ > > > p2m_to_mask(p2m_ram_ro)) > > > > > > +/* Grant mapping types, which map to a real frame in another VM */ > > > +#define P2M_GRANT_TYPES (p2m_to_mask(p2m_grant_map_rw) | \ > > > + p2m_to_mask(p2m_grant_map_ro)) > > > + > > > /* Useful predicates */ > > > #define p2m_is_ram(_t) (p2m_to_mask(_t) & P2M_RAM_TYPES) > > > #define p2m_is_foreign(_t) (p2m_to_mask(_t) & > > > p2m_to_mask(p2m_map_foreign)) > > > +#define p2m_is_any_ram(_t) (p2m_to_mask(_t) & \ > > > + (P2M_RAM_TYPES | P2M_GRANT_TYPES | \ > > > + p2m_to_mask(p2m_map_foreign))) > > > > > > static inline > > > void p2m_mem_access_emulate_check(struct vcpu *v, > > > @@ -224,7 +231,7 @@ static inline struct page_info *get_page_from_gfn( > > > if (t) > > > *t = p2mt; > > > > > > - if ( p2mt == p2m_invalid || p2mt == p2m_mmio_direct ) > > > + if ( !p2m_is_any_ram(p2mt) ) > > > return NULL; > > > > What about the iommu mappings? > > iommu mappings (p2m_iommu_map_*) are special mappings for the direct mapping > workaround. They should not be used in get_page_from_gfn. Make sense. I think they deserve to be mentioned in the commit message, as this patch changes behavior for them. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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