| Date | Fri, 15 Apr 2022 16:06:02 +0200 | Subject | Re: [RFC PATCH v5 068/104] KVM: TDX: restore user ret MSRs | From | Paolo Bonzini <> |
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On 3/4/22 20:49, isaku.yamahata@intel.com wrote: > From: Isaku Yamahata <isaku.yamahata@intel.com> > > Several user ret MSRs are clobbered on TD exit. Restore those values on > TD exit and before returning to ring 3. > > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> > --- > arch/x86/kvm/vmx/tdx.c | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c > index 54be5be1a06c..c1366aac7d96 100644 > --- a/arch/x86/kvm/vmx/tdx.c > +++ b/arch/x86/kvm/vmx/tdx.c > @@ -550,6 +550,28 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > vcpu->kvm->vm_bugged = true; > } > > +struct tdx_uret_msr { > + u32 msr; > + unsigned int slot; > + u64 defval; > +}; > + > +static struct tdx_uret_msr tdx_uret_msrs[] = { > + {.msr = MSR_SYSCALL_MASK,}, > + {.msr = MSR_STAR,}, > + {.msr = MSR_LSTAR,}, > + {.msr = MSR_TSC_AUX,}, > +}; > + > +static void tdx_user_return_update_cache(void) > +{ > + int i; > + > + for (i = 0; i < ARRAY_SIZE(tdx_uret_msrs); i++) > + kvm_user_return_update_cache(tdx_uret_msrs[i].slot, > + tdx_uret_msrs[i].defval); > +} > + > static void tdx_restore_host_xsave_state(struct kvm_vcpu *vcpu) > { > struct kvm_tdx *kvm_tdx = to_kvm_tdx(vcpu->kvm); > @@ -589,6 +611,7 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu) > > tdx_vcpu_enter_exit(vcpu, tdx); > > + tdx_user_return_update_cache(); > tdx_restore_host_xsave_state(vcpu); > tdx->host_state_need_restore = true; > > @@ -1371,6 +1394,16 @@ static int __init __tdx_hardware_setup(struct kvm_x86_ops *x86_ops) > if (WARN_ON_ONCE(x86_ops->tlb_remote_flush)) > return -EIO; > > + for (i = 0; i < ARRAY_SIZE(tdx_uret_msrs); i++) { > + tdx_uret_msrs[i].slot = kvm_find_user_return_msr(tdx_uret_msrs[i].msr); > + if (tdx_uret_msrs[i].slot == -1) { > + /* If any MSR isn't supported, it is a KVM bug */ > + pr_err("MSR %x isn't included by kvm_find_user_return_msr\n", > + tdx_uret_msrs[i].msr); > + return -EIO; > + } > + } > + > max_pkgs = topology_max_packages(); > tdx_mng_key_config_lock = kcalloc(max_pkgs, sizeof(*tdx_mng_key_config_lock), > GFP_KERNEL);
I wonder if you only need to do this if !this_cpu_ptr(user_return_msrs)->registered, but not a big deal.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
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