From 4c93bec108f7e3918a2ef91b51cec477ade38cc3 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 18 Mar 2024 17:45:56 -0400 Subject: [PATCH 018/100] runstate: skip initial CPU reset if reset is not actually possible MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Paolo Bonzini RH-MergeRequest: 245: SEV-SNP support RH-Jira: RHEL-39544 RH-Acked-by: Thomas Huth RH-Acked-by: Bandan Das RH-Acked-by: Vitaly Kuznetsov RH-Commit: [18/91] ced267fdaadbf2072c1897223522457a006e6c81 (bonzini/rhel-qemu-kvm) Right now, the system reset is concluded by a call to cpu_synchronize_all_post_reset() in order to sync any changes that the machine reset callback applied to the CPU state. However, for VMs with encrypted state such as SEV-ES guests (currently the only case of guests with non-resettable CPUs) this cannot be done, because guest state has already been finalized by machine-init-done notifiers. cpu_synchronize_all_post_reset() does nothing on these guests, and actually we would like to make it fail if called once guest has been encrypted. So, assume that boards that support non-resettable CPUs do not touch CPU state and that all such setup is done before, at the time of cpu_synchronize_all_post_init(). Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Paolo Bonzini (cherry picked from commit 08b2d15cdd0d3fbbe37ce23bf192b770db3a7539) Signed-off-by: Paolo Bonzini --- system/runstate.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/system/runstate.c b/system/runstate.c index d6ab860eca..cb4905a40f 100644 --- a/system/runstate.c +++ b/system/runstate.c @@ -501,7 +501,20 @@ void qemu_system_reset(ShutdownCause reason) default: qapi_event_send_reset(shutdown_caused_by_guest(reason), reason); } - cpu_synchronize_all_post_reset(); + + /* + * Some boards use the machine reset callback to point CPUs to the firmware + * entry point. Assume that this is not the case for boards that support + * non-resettable CPUs (currently used only for confidential guests), in + * which case cpu_synchronize_all_post_init() is enough because + * it does _more_ than cpu_synchronize_all_post_reset(). + */ + if (cpus_are_resettable()) { + cpu_synchronize_all_post_reset(); + } else { + assert(runstate_check(RUN_STATE_PRELAUNCH)); + } + vm_set_suspended(false); } -- 2.39.3