GHES: Seriously speedup and cleanup NMI handler (Jiri Kosina and Borislav Petkov)
This is the result of us seeing this during boot [ 24.332560] INFO: NMI handler (ghes_notify_nmi) took too long to run: 3.265 msecs [ 24.332567] INFO: NMI handler (ghes_notify_nmi) took too long to run: 5.946 msecs [ 24.332568] INFO: NMI handler (ghes_notify_nmi) took too long to run: 5.948 msecs and a report of people running perf stat and the machine softlocking. "hest_disable" was helping in this case, which made us look at that particular NMI handler. It was grabbing a lock each time it is run and on each CPU. But this is not needed as the GHES sources are global and they need only a single reader. This patchset does that and cleans up the handler in the process. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAABAgAGBQJVRzqjAAoJEBLB8Bhh3lVKFQUQAKmPPaWp2qPUkRHtrdFfae0n Um9PSAHlvO8oHPrr+5j+CEVX1gQ1qUFMuxSVuBYYhmMZnsAVCwKX8gOi3slZmElo L0MoqxygP2v3Rc79Jk8KEkov+80zzp46VoB5Yh0mTfzSejeS+c1owwS0RzVIpda3 Zp1cAThTVsCdDmmWGhnWfc8T/wniPc2zbbVhtjivO/wwSu7ArWUR5/03pbxzex8M 3xnJY29USB62xO5OJf0mxAIhTqv4a7NSQ6NziBrI2Mt4inHj0oSR7KLVFpeSx4mX LLo8dWfDpMIbwd2sZYg5fG6Kz2i3Cc5I252V4j7MI+srvvZzZPBr1aB8qNyQVGPF grrQKQuD2Az0WZRo2gK2LvxvlHfmJyOJMaFPW+RMnARbtKMmmAIwaN4+zmPGHoH8 aQK7cKUyb1JxICpy9iAZjXMvqxc5zbhYra0G+zuLKruhEvmLrwibphjI82BNdaBZ rhkK+cw47lPgwKVNRWKjpNGGziwqU2cBlmc50k9OyQhhv5HF2TeYyBRryykOVmLV DpsUxO4rCj0YEioyoJEruBO1Ks167HGrg5sbSemO/YeM7wLgr7hMfVNlGM4DI68X b3Ie81/7qD8d3nQZ/gkk8ex1D0QhS0FWZthbNKpvkX+Zc/ELbGhfgHxX55HmfGuD DUmvP2oXlALAIPiJAYVP =Qj+0 -----END PGP SIGNATURE----- Merge tag 'ras_for_4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras into acpi-apei Pull GHES changes for 4.2 from Borislav Petkov: "GHES: Seriously speedup and cleanup NMI handler (Jiri Kosina and Borislav Petkov) This is the result of us seeing this during boot [ 24.332560] INFO: NMI handler (ghes_notify_nmi) took too long to run: 3.265 msecs [ 24.332567] INFO: NMI handler (ghes_notify_nmi) took too long to run: 5.946 msecs [ 24.332568] INFO: NMI handler (ghes_notify_nmi) took too long to run: 5.948 msecs and a report of people running perf stat and the machine softlocking. "hest_disable" was helping in this case, which made us look at that particular NMI handler. It was grabbing a lock each time it is run and on each CPU. But this is not needed as the GHES sources are global and they need only a single reader. This patchset does that and cleans up the handler in the process." * tag 'ras_for_4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras: GHES: Make NMI handler have a single reader GHES: Elliminate double-loop in the NMI handler GHES: Panic right after detection GHES: Carve out the panic functionality GHES: Carve out error queueing in a separate function
This commit is contained in:
Rafael J. Wysocki
commit
20f34165a9
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@ -729,10 +729,10 @@ static struct llist_head ghes_estatus_llist;
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static struct irq_work ghes_proc_irq_work;
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/*
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* NMI may be triggered on any CPU, so ghes_nmi_lock is used for
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* mutual exclusion.
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* NMI may be triggered on any CPU, so ghes_in_nmi is used for
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* having only one concurrent reader.
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*/
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static DEFINE_RAW_SPINLOCK(ghes_nmi_lock);
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static atomic_t ghes_in_nmi = ATOMIC_INIT(0);
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static LIST_HEAD(ghes_nmi);
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@ -797,73 +797,75 @@ static void ghes_print_queued_estatus(void)
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}
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}
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/* Save estatus for further processing in IRQ context */
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static void __process_error(struct ghes *ghes)
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{
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#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
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u32 len, node_len;
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struct ghes_estatus_node *estatus_node;
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struct acpi_hest_generic_status *estatus;
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if (ghes_estatus_cached(ghes->estatus))
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return;
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len = cper_estatus_len(ghes->estatus);
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node_len = GHES_ESTATUS_NODE_LEN(len);
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estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool, node_len);
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if (!estatus_node)
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return;
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estatus_node->ghes = ghes;
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estatus_node->generic = ghes->generic;
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estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
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memcpy(estatus, ghes->estatus, len);
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llist_add(&estatus_node->llnode, &ghes_estatus_llist);
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#endif
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}
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static void __ghes_panic(struct ghes *ghes)
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{
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oops_begin();
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ghes_print_queued_estatus();
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__ghes_print_estatus(KERN_EMERG, ghes->generic, ghes->estatus);
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/* reboot to log the error! */
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if (panic_timeout == 0)
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panic_timeout = ghes_panic_timeout;
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panic("Fatal hardware error!");
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}
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static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
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{
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struct ghes *ghes, *ghes_global = NULL;
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int sev, sev_global = -1;
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int ret = NMI_DONE;
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struct ghes *ghes;
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int sev, ret = NMI_DONE;
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if (!atomic_add_unless(&ghes_in_nmi, 1, 1))
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return ret;
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raw_spin_lock(&ghes_nmi_lock);
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list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
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if (ghes_read_estatus(ghes, 1)) {
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ghes_clear_estatus(ghes);
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continue;
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}
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sev = ghes_severity(ghes->estatus->error_severity);
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if (sev > sev_global) {
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sev_global = sev;
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ghes_global = ghes;
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}
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if (sev >= GHES_SEV_PANIC)
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__ghes_panic(ghes);
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if (!(ghes->flags & GHES_TO_CLEAR))
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continue;
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__process_error(ghes);
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ghes_clear_estatus(ghes);
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ret = NMI_HANDLED;
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}
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if (ret == NMI_DONE)
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goto out;
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if (sev_global >= GHES_SEV_PANIC) {
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oops_begin();
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ghes_print_queued_estatus();
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__ghes_print_estatus(KERN_EMERG, ghes_global->generic,
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ghes_global->estatus);
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/* reboot to log the error! */
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if (panic_timeout == 0)
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panic_timeout = ghes_panic_timeout;
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panic("Fatal hardware error!");
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}
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list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
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#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
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u32 len, node_len;
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struct ghes_estatus_node *estatus_node;
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struct acpi_hest_generic_status *estatus;
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#endif
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if (!(ghes->flags & GHES_TO_CLEAR))
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continue;
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#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
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if (ghes_estatus_cached(ghes->estatus))
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goto next;
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/* Save estatus for further processing in IRQ context */
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len = cper_estatus_len(ghes->estatus);
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node_len = GHES_ESTATUS_NODE_LEN(len);
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estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool,
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node_len);
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if (estatus_node) {
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estatus_node->ghes = ghes;
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estatus_node->generic = ghes->generic;
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estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
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memcpy(estatus, ghes->estatus, len);
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llist_add(&estatus_node->llnode, &ghes_estatus_llist);
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}
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next:
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#endif
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ghes_clear_estatus(ghes);
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}
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#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
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irq_work_queue(&ghes_proc_irq_work);
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#endif
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out:
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raw_spin_unlock(&ghes_nmi_lock);
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atomic_dec(&ghes_in_nmi);
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return ret;
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}
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