Commit Message
Isaku Yamahata
Feb. 26, 2024, 8:26 a.m. UTC
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. Because TSX_CTRL requires special treat, this patch doesn't address it. Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/vmx/tdx.c | 43 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+)
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 199226c6cf55..7e2b1e554246 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -535,6 +535,28 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) */ } +struct tdx_uret_msr { + u32 msr; + unsigned int slot; + u64 defval; +}; + +static struct tdx_uret_msr tdx_uret_msrs[] = { + {.msr = MSR_SYSCALL_MASK, .defval = 0x20200 }, + {.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); @@ -627,6 +649,7 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu) tdx_vcpu_enter_exit(tdx); + tdx_user_return_update_cache(); tdx_restore_host_xsave_state(vcpu); tdx->host_state_need_restore = true; @@ -1972,6 +1995,26 @@ int __init tdx_hardware_setup(struct kvm_x86_ops *x86_ops) return -EINVAL; } + for (i = 0; i < ARRAY_SIZE(tdx_uret_msrs); i++) { + /* + * Here it checks if MSRs (tdx_uret_msrs) can be saved/restored + * before returning to user space. + * + * this_cpu_ptr(user_return_msrs)->registered isn't checked + * because the registration is done at vcpu runtime by + * kvm_set_user_return_msr(). + * Here is setting up cpu feature before running vcpu, + * registered is already false. + */ + 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);