HI Jens, > On 22 Feb 2023, at 16:33, Jens Wiklander <jens.wiklan...@linaro.org> wrote: > > Adds a BUILD_BUG_ON() to assert the dependency on 4k pages in the FF-A > mediator. > > Signed-off-by: Jens Wiklander <jens.wiklan...@linaro.org>
NIT: I would s/note/enforce/ in the title: xen/arm: ffa: enforce 4k pages Reviewed-by: Bertrand Marquis <bertrand.marq...@arm.com> Cheers Bertrand > --- > xen/arch/arm/tee/ffa.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/xen/arch/arm/tee/ffa.c b/xen/arch/arm/tee/ffa.c > index d04bac9cc47f..8b0b80ce1ff5 100644 > --- a/xen/arch/arm/tee/ffa.c > +++ b/xen/arch/arm/tee/ffa.c > @@ -56,6 +56,16 @@ > #define FFA_MY_VERSION MAKE_FFA_VERSION(FFA_MY_VERSION_MAJOR, \ > FFA_MY_VERSION_MINOR) > > +/* > + * The FF-A specification explicitly works with 4K pages as a measure of > + * memory size, for example, FFA_RXTX_MAP takes one parameter "RX/TX page > + * count" which is the number of contiguous 4K pages allocated. Xen may use > + * a different page size depending on the configuration to avoid confusion > + * with PAGE_SIZE use a special define when it's a page size as in the FF-A > + * specification. > + */ > +#define FFA_PAGE_SIZE SZ_4K > + > /* Framework direct request/response */ > #define FFA_MSG_FLAG_FRAMEWORK BIT(31, U) > #define FFA_MSG_TYPE_MASK 0xFFU; > @@ -242,6 +252,17 @@ static bool ffa_probe(void) > unsigned int major_vers; > unsigned int minor_vers; > > + /* > + * FF-A often works in units of 4K pages and currently it's assumed > + * that we can map memory using that granularity. See also the comment > + * above the FFA_PAGE_SIZE define. > + * > + * It is possible to support a PAGE_SIZE larger than 4K in Xen, but > + * until that is fully handled in this code make sure that we only use > + * 4K page sizes. > + */ > + BUILD_BUG_ON(PAGE_SIZE != FFA_PAGE_SIZE); > + > /* > * psci_init_smccc() updates this value with what's reported by EL-3 > * or secure world. > -- > 2.34.1 >
