On Wed, 2022-05-18 at 09:19 -0700, Sagi Shahar wrote: > On Tue, Apr 26, 2022 at 5:06 PM Kai Huang <kai.huang@xxxxxxxxx> wrote: > > > > On Tue, 2022-04-26 at 13:59 -0700, Dave Hansen wrote: > > > On 4/5/22 21:49, Kai Huang wrote: > > > > TDX supports shutting down the TDX module at any time during its > > > > lifetime. After TDX module is shut down, no further SEAMCALL can be > > > > made on any logical cpu. > > > > > > Is this strictly true? > > > > > > I thought SEAMCALLs were used for the P-SEAMLDR too. > > > > Sorry will change to no TDX module SEAMCALL can be made on any logical cpu. > > > > [...] > > > > > > > > > > +/* Data structure to make SEAMCALL on multiple CPUs concurrently */ > > > > +struct seamcall_ctx { > > > > + u64 fn; > > > > + u64 rcx; > > > > + u64 rdx; > > > > + u64 r8; > > > > + u64 r9; > > > > + atomic_t err; > > > > + u64 seamcall_ret; > > > > + struct tdx_module_output out; > > > > +}; > > > > + > > > > +static void seamcall_smp_call_function(void *data) > > > > +{ > > > > + struct seamcall_ctx *sc = data; > > > > + int ret; > > > > + > > > > + ret = seamcall(sc->fn, sc->rcx, sc->rdx, sc->r8, sc->r9, > > > > + &sc->seamcall_ret, &sc->out); > > Are the seamcall_ret and out fields in seamcall_ctx going to be used? > Right now it looks like no one is going to read them. > If they are going to be used then this is going to cause a race since > the different CPUs are going to write concurrently to the same address > inside seamcall(). > We should either use local memory and write using atomic_set like the > case for the err field or hard code NULL at the call site if they are > not going to be used. > > > > Thanks for catching this. Both 'seamcall_ret' and 'out' are actually not used in this series, but this needs to be improved for sure. I think I can just remove them from the 'seamcall_ctx' for now, since they are not used at all. -- Thanks, -Kai