On Tue, Jan 18, 2022 at 08:23:45AM -0600, Michael Roth wrote: > On Tue, Jan 18, 2022 at 03:02:48PM +0100, Borislav Petkov wrote: > > On Mon, Jan 17, 2022 at 10:35:21PM -0600, Michael Roth wrote: > > > Unfortunately, in sev_enable(), between the point where snp_init() is > > > called, and sev_status is actually set, there are a number of cpuid > > > intructions which will make use of do_vc_no_ghcb() prior to sev_status > > > being set (and it needs to happen in that order to set sev_status > > > appropriately). After that point, snp_cpuid_active() would no longer be > > > necessary, but during that span some indicator is needed in case this > > > is just an SEV-ES guest trigger cpuid #VCs. > > > > You mean testing what snp_cpuid_info_create() set up is not enough? > > > > diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c > > index 7bc7e297f88c..17cfe804bad3 100644 > > --- a/arch/x86/kernel/sev-shared.c > > +++ b/arch/x86/kernel/sev-shared.c > > @@ -523,7 +523,9 @@ static int snp_cpuid_postprocess(u32 func, u32 subfunc, u32 *eax, u32 *ebx, > > static int snp_cpuid(u32 func, u32 subfunc, u32 *eax, u32 *ebx, u32 *ecx, > > u32 *edx) > > { > > - if (!snp_cpuid_active()) > > + const struct snp_cpuid_info *c = snp_cpuid_info_get_ptr(); > > + > > + if (!c->count) > > return -EOPNOTSUPP; > > > > if (!snp_cpuid_find_validated_func(func, subfunc, eax, ebx, ecx, edx)) { > > snp_cpuid_info_get_ptr() will always return non-NULL, since it's a > pointer to the local copy of the cpuid page. But I can probably re-work Doh, misread your patch. Yes I think checking the count would also work, since a valid table should be non-zero.