On Wed, Nov 23, 2022 at 09:18:39AM +0100, Eric Auger wrote: > Hi, > > On 11/23/22 07:36, Michael S. Tsirkin wrote: > > On Fri, May 06, 2022 at 09:47:52AM -0400, Stefan Berger wrote: > >> > >> On 5/6/22 09:25, Eric Auger wrote: > >>> In a subsequent patch, VFIO will need to recognize if > >>> a memory region owner is a TPM CRB device. Hence VFIO > >>> needs to use TPM_IS_CRB() even if CONFIG_TPM is unset. So > >>> let's add a stub function. > >>> > >>> Signed-off-by: Eric Auger <eric.au...@redhat.com> > >>> Suggested-by: Cornelia Huck <coh...@redhat.com> > >> Reviewed-by: Stefan Berger <stef...@linnux.ibm.com> > > ... and now in 7.2 vdpa needs a dependency on tpm too, what a hack :( > > And what exactly is it about TPM CRB that everyone needs to > > know about it and skip it? The API does not tell ... > An excerpt of one reply I made at that time: > > The spec (CG PC Client Platform TPM Profile (PTP) > Specification Family “2.0” Level 00 Revision 01.03 v22, page 100) > says that the command/response data "may be defined as large as 3968", > which is (0x1000 - 0x80), 0x80 being the size of the control struct. > so the size of the region logically is less than a 4kB page, hence our > trouble. > > We learnt in the past Windows driver has some stronger expectation wrt > memory mapping. I don't know if those latter would work if we were to > enlarge the window by some tricks. > > https://trustedcomputinggroup.org/wp-content/uploads/Mobile-Command-Response-Buffer-Interface-v2-r12-Specification_FINAL2.pdf > says > > " > Including the control structure, the three memory areas comprise the > entirety of the CRB. There are no constraints on how those three memory > areas are provided. They can all be in system RAM, or all be in device > memory, or any combination. > > Thanks > > Eric
So we put it in system RAM then? But why isn't DMA there allowed? > > > >>> --- > >>> include/sysemu/tpm.h | 6 ++++++ > >>> 1 file changed, 6 insertions(+) > >>> > >>> diff --git a/include/sysemu/tpm.h b/include/sysemu/tpm.h > >>> index 68b2206463c..fb40e30ff60 100644 > >>> --- a/include/sysemu/tpm.h > >>> +++ b/include/sysemu/tpm.h > >>> @@ -80,6 +80,12 @@ static inline TPMVersion tpm_get_version(TPMIf *ti) > >>> #define tpm_init() (0) > >>> #define tpm_cleanup() > >>> > >>> +/* needed for an alignment check in non-tpm code */ > >>> +static inline Object *TPM_IS_CRB(Object *obj) > >>> +{ > >>> + return NULL; > >>> +} > >>> + > >>> #endif /* CONFIG_TPM */ > >>> > >>> #endif /* QEMU_TPM_H */ > >>