From: Chao Gao <chao.gao@intel.com> To: Sergey Dyasli <sergey.dyasli@citrix.com> Cc: "Kevin Tian" <kevin.tian@intel.com>, "Ashok Raj" <ashok.raj@intel.com>, "Wei Liu" <wl@xen.org>, "Andrew Cooper" <andrew.cooper3@citrix.com>, "Jan Beulich" <jbeulich@suse.com>, "Jun Nakajima" <jun.nakajima@intel.com>, xen-devel@lists.xenproject.org, "Thomas Gleixner" <tglx@linutronix.de>, "Borislav Petkov" <bp@suse.de>, "Roger Pau Monné" <roger.pau@citrix.com> Subject: Re: [Xen-devel] [PATCH v9 13/15] x86/microcode: Synchronize late microcode loading Date: Mon, 19 Aug 2019 22:49:36 +0800 Message-ID: <20190819144934.GA12597@gao-cwp> (raw) In-Reply-To: <ea4e0bee-7151-82da-c293-fec2532f9b92@citrix.com> On Mon, Aug 19, 2019 at 11:27:36AM +0100, Sergey Dyasli wrote: >> +static int master_thread_fn(const struct microcode_patch *patch) >> +{ >> + unsigned int cpu = smp_processor_id(); >> + int ret = 0; >> + >> + while ( loading_state != LOADING_CALLIN ) >> + cpu_relax(); >> + >> + cpumask_set_cpu(cpu, &cpu_callin_map); >> + >> + while ( loading_state != LOADING_ENTER ) >> + cpu_relax(); > >If I'm reading it right, this will wait forever in case when... > >> + >> + /* >> + * If an error happened, control thread would set 'loading_state' >> + * to LOADING_EXIT. Don't perform ucode loading for this case >> + */ >> + if ( loading_state == LOADING_EXIT ) >> + return ret; I tried to check whether there was an error here. But as you said, we cannot reach here if 'control thread' set loading_state from LOADING_CALLIN to LOADING_EXIT. I will do this check in the while-loop right above. >> + >> + ret = microcode_ops->apply_microcode(patch); >> + if ( !ret ) >> + atomic_inc(&cpu_updated); >> + atomic_inc(&cpu_out); >> + >> + while ( loading_state != LOADING_EXIT ) >> + cpu_relax(); >> + >> + return ret; >> +} >> + >> +static int control_thread_fn(const struct microcode_patch *patch) >> { >> - unsigned int cpu; >> + unsigned int cpu = smp_processor_id(), done; >> + unsigned long tick; >> + int ret; >> >> - /* Store the patch after a successful loading */ >> - if ( !microcode_update_cpu(patch) && patch ) >> + /* Allow threads to call in */ >> + loading_state = LOADING_CALLIN; >> + smp_mb(); >> + >> + cpumask_set_cpu(cpu, &cpu_callin_map); >> + >> + /* Waiting for all threads calling in */ >> + ret = wait_for_condition(wait_cpu_callin, >> + (void *)(unsigned long)num_online_cpus(), >> + MICROCODE_CALLIN_TIMEOUT_US); >> + if ( ret ) { >> + loading_state = LOADING_EXIT; >> + return ret; >> + } > >...this condition holds. Have you actually tested this case? I didn't craft a case to verify the error-handling path. And I believe that you are right. Thanks Chao _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply index Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-19 1:25 [Xen-devel] [PATCH v9 00/15] improve " Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 01/15] microcode/intel: extend microcode_update_match() Chao Gao 2019-08-28 15:12 ` Jan Beulich 2019-08-29 7:15 ` Chao Gao 2019-08-29 7:14 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 02/15] microcode/amd: fix memory leak Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 03/15] microcode/amd: distinguish old and mismatched ucode in microcode_fits() Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 04/15] microcode: introduce a global cache of ucode patch Chao Gao 2019-08-22 11:11 ` Roger Pau Monné 2019-08-28 15:21 ` Jan Beulich 2019-08-29 10:18 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 05/15] microcode: clean up microcode_resume_cpu Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 06/15] microcode: remove struct ucode_cpu_info Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 07/15] microcode: remove pointless 'cpu' parameter Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 08/15] microcode/amd: call svm_host_osvw_init() in common code Chao Gao 2019-08-22 13:08 ` Roger Pau Monné 2019-08-28 15:26 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 09/15] microcode: pass a patch pointer to apply_microcode() Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 10/15] microcode: split out apply_microcode() from cpu_request_microcode() Chao Gao 2019-08-22 13:59 ` Roger Pau Monné 2019-08-29 10:06 ` Jan Beulich 2019-08-30 3:22 ` Chao Gao 2019-08-30 7:25 ` Jan Beulich 2019-08-29 10:19 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 11/15] microcode: unify loading update during CPU resuming and AP wakeup Chao Gao 2019-08-22 14:10 ` Roger Pau Monné 2019-08-22 16:44 ` Chao Gao 2019-08-23 9:09 ` Roger Pau Monné 2019-08-29 7:37 ` Chao Gao 2019-08-29 8:16 ` Roger Pau Monné 2019-08-29 10:26 ` Jan Beulich 2019-08-29 10:29 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 12/15] microcode: reduce memory allocation and copy when creating a patch Chao Gao 2019-08-23 8:11 ` Roger Pau Monné 2019-08-26 7:03 ` Chao Gao 2019-08-26 8:11 ` Roger Pau Monné 2019-08-29 10:47 ` Jan Beulich 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 13/15] x86/microcode: Synchronize late microcode loading Chao Gao 2019-08-19 10:27 ` Sergey Dyasli 2019-08-19 14:49 ` Chao Gao [this message] 2019-08-29 12:06 ` Jan Beulich 2019-08-30 3:30 ` Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 14/15] microcode: remove microcode_update_lock Chao Gao 2019-08-19 1:25 ` [Xen-devel] [PATCH v9 15/15] microcode: block #NMI handling when loading an ucode Chao Gao 2019-08-23 8:46 ` Sergey Dyasli 2019-08-26 8:07 ` Chao Gao 2019-08-27 4:52 ` Chao Gao 2019-08-28 8:52 ` Sergey Dyasli 2019-08-29 12:11 ` Jan Beulich 2019-08-30 6:35 ` Chao Gao 2019-09-09 5:52 ` Chao Gao 2019-09-09 6:16 ` Jan Beulich 2019-08-29 12:22 ` Jan Beulich 2019-08-30 6:33 ` Chao Gao 2019-08-30 7:30 ` Jan Beulich 2019-08-22 7:51 ` [Xen-devel] [PATCH v9 00/15] improve late microcode loading Sergey Dyasli 2019-08-22 15:39 ` Chao Gao
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