![Mahesh Salgaonkar](/assets/img/avatar_default.png)
Currently we forward MCEs to guest which have been recovered by guest. And for unhandled errors we do not deliver the MCE to guest. It looks like with no support of FWNMI in qemu, guest just panics whenever we deliver the recovered MCEs to guest. Also, the existig code used to return to host for unhandled errors which was casuing guest to hang with soft lockups inside guest and makes it difficult to recover guest instance. This patch now forwards all fatal MCEs to guest causing guest to crash/panic. And, for recovered errors we just go back to normal functioning of guest instead of returning to host. This fixes soft lockup issues in guest. This patch also fixes an issue where guest MCE events were not logged to host console. Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
146 lines
4.3 KiB
C
146 lines
4.3 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License, version 2, as
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* published by the Free Software Foundation.
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*
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* Copyright 2012 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
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*/
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/kvm.h>
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#include <linux/kvm_host.h>
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#include <linux/kernel.h>
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#include <asm/opal.h>
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#include <asm/mce.h>
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/* SRR1 bits for machine check on POWER7 */
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#define SRR1_MC_LDSTERR (1ul << (63-42))
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#define SRR1_MC_IFETCH_SH (63-45)
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#define SRR1_MC_IFETCH_MASK 0x7
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#define SRR1_MC_IFETCH_SLBPAR 2 /* SLB parity error */
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#define SRR1_MC_IFETCH_SLBMULTI 3 /* SLB multi-hit */
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#define SRR1_MC_IFETCH_SLBPARMULTI 4 /* SLB parity + multi-hit */
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#define SRR1_MC_IFETCH_TLBMULTI 5 /* I-TLB multi-hit */
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/* DSISR bits for machine check on POWER7 */
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#define DSISR_MC_DERAT_MULTI 0x800 /* D-ERAT multi-hit */
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#define DSISR_MC_TLB_MULTI 0x400 /* D-TLB multi-hit */
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#define DSISR_MC_SLB_PARITY 0x100 /* SLB parity error */
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#define DSISR_MC_SLB_MULTI 0x080 /* SLB multi-hit */
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#define DSISR_MC_SLB_PARMULTI 0x040 /* SLB parity + multi-hit */
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/* POWER7 SLB flush and reload */
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static void reload_slb(struct kvm_vcpu *vcpu)
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{
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struct slb_shadow *slb;
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unsigned long i, n;
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/* First clear out SLB */
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asm volatile("slbmte %0,%0; slbia" : : "r" (0));
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/* Do they have an SLB shadow buffer registered? */
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slb = vcpu->arch.slb_shadow.pinned_addr;
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if (!slb)
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return;
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/* Sanity check */
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n = min_t(u32, slb->persistent, SLB_MIN_SIZE);
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if ((void *) &slb->save_area[n] > vcpu->arch.slb_shadow.pinned_end)
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return;
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/* Load up the SLB from that */
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for (i = 0; i < n; ++i) {
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unsigned long rb = slb->save_area[i].esid;
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unsigned long rs = slb->save_area[i].vsid;
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rb = (rb & ~0xFFFul) | i; /* insert entry number */
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asm volatile("slbmte %0,%1" : : "r" (rs), "r" (rb));
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}
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}
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/*
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* On POWER7, see if we can handle a machine check that occurred inside
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* the guest in real mode, without switching to the host partition.
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*
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* Returns: 0 => exit guest, 1 => deliver machine check to guest
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*/
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static long kvmppc_realmode_mc_power7(struct kvm_vcpu *vcpu)
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{
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unsigned long srr1 = vcpu->arch.shregs.msr;
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struct machine_check_event mce_evt;
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long handled = 1;
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if (srr1 & SRR1_MC_LDSTERR) {
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/* error on load/store */
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unsigned long dsisr = vcpu->arch.shregs.dsisr;
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if (dsisr & (DSISR_MC_SLB_PARMULTI | DSISR_MC_SLB_MULTI |
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DSISR_MC_SLB_PARITY | DSISR_MC_DERAT_MULTI)) {
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/* flush and reload SLB; flushes D-ERAT too */
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reload_slb(vcpu);
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dsisr &= ~(DSISR_MC_SLB_PARMULTI | DSISR_MC_SLB_MULTI |
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DSISR_MC_SLB_PARITY | DSISR_MC_DERAT_MULTI);
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}
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if (dsisr & DSISR_MC_TLB_MULTI) {
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if (cur_cpu_spec && cur_cpu_spec->flush_tlb)
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cur_cpu_spec->flush_tlb(TLBIEL_INVAL_SET_LPID);
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dsisr &= ~DSISR_MC_TLB_MULTI;
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}
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/* Any other errors we don't understand? */
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if (dsisr & 0xffffffffUL)
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handled = 0;
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}
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switch ((srr1 >> SRR1_MC_IFETCH_SH) & SRR1_MC_IFETCH_MASK) {
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case 0:
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break;
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case SRR1_MC_IFETCH_SLBPAR:
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case SRR1_MC_IFETCH_SLBMULTI:
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case SRR1_MC_IFETCH_SLBPARMULTI:
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reload_slb(vcpu);
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break;
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case SRR1_MC_IFETCH_TLBMULTI:
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if (cur_cpu_spec && cur_cpu_spec->flush_tlb)
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cur_cpu_spec->flush_tlb(TLBIEL_INVAL_SET_LPID);
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break;
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default:
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handled = 0;
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}
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/*
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* See if we have already handled the condition in the linux host.
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* We assume that if the condition is recovered then linux host
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* will have generated an error log event that we will pick
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* up and log later.
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* Don't release mce event now. We will queue up the event so that
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* we can log the MCE event info on host console.
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*/
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if (!get_mce_event(&mce_evt, MCE_EVENT_DONTRELEASE))
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goto out;
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if (mce_evt.version == MCE_V1 &&
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(mce_evt.severity == MCE_SEV_NO_ERROR ||
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mce_evt.disposition == MCE_DISPOSITION_RECOVERED))
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handled = 1;
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out:
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/*
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* We are now going enter guest either through machine check
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* interrupt (for unhandled errors) or will continue from
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* current HSRR0 (for handled errors) in guest. Hence
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* queue up the event so that we can log it from host console later.
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*/
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machine_check_queue_event();
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return handled;
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}
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long kvmppc_realmode_machine_check(struct kvm_vcpu *vcpu)
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{
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if (cpu_has_feature(CPU_FTR_ARCH_206))
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return kvmppc_realmode_mc_power7(vcpu);
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return 0;
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}
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