static void mce_checkregs (void *info)
{
mctelem_cookie_t mctc;
struct mca_summary bs;
static uint64_t dumpcount = 0;
mctc = mcheck_mca_logout(MCA_POLLER, __get_cpu_var(poll_bankmask), &bs);
if (bs.errcnt && mctc != NULL) {
adjust++;
/* If Dom0 enabled the VIRQ_MCA event, then notify it.
* Otherwise, if dom0 has had plenty of time to register
* the virq handler but still hasn't then dump telemetry
* to the Xen console. The call count may be incremented
* on multiple cpus at once and is indicative only - just
* a simple-minded attempt to avoid spamming the console
* for corrected errors in early startup.
*/
if (guest_enabled_event(dom0->vcpu[0], VIRQ_MCA)) {
mctelem_commit(mctc);
send_guest_global_virq(dom0, VIRQ_MCA);
} else if (++dumpcount >= 10) {
x86_mcinfo_dump((struct mc_info *)mctelem_dataptr(mctc));
mctelem_dismiss(mctc);
} else {
mctelem_dismiss(mctc);
}
} else if (mctc != NULL) {
mctelem_dismiss(mctc);
}
}
/* Add out_param clear_bank for Machine Check Handler Caller.
* For Intel latest CPU, whether to clear the error bank status needs to
* be judged by the callback function defined above.
*/
mctelem_cookie_t
mcheck_mca_logout(enum mca_source who, struct mca_banks *bankmask,
struct mca_summary *sp, struct mca_banks *clear_bank)
{
uint64_t gstatus, status;
struct mcinfo_global *mig = NULL; /* on stack */
mctelem_cookie_t mctc = NULL;
bool_t uc = 0, pcc = 0, recover = 1, need_clear = 1;
uint32_t mc_flags = 0;
struct mc_info *mci = NULL;
mctelem_class_t which = MC_URGENT; /* XXXgcc */
int errcnt = 0;
int i;
gstatus = mca_rdmsr(MSR_IA32_MCG_STATUS);
switch (who) {
case MCA_MCE_SCAN:
mc_flags = MC_FLAG_MCE;
which = MC_URGENT;
break;
case MCA_POLLER:
case MCA_RESET:
mc_flags = MC_FLAG_POLLED;
which = MC_NONURGENT;
break;
case MCA_CMCI_HANDLER:
mc_flags = MC_FLAG_CMCI;
which = MC_NONURGENT;
break;
default:
BUG();
}
/* If no mc_recovery_scan callback handler registered,
* this error is not recoverable
*/
recover = (mc_recoverable_scan) ? 1 : 0;
for (i = 0; i < nr_mce_banks; i++) {
/* Skip bank if corresponding bit in bankmask is clear */
if (!mcabanks_test(i, bankmask))
continue;
status = mca_rdmsr(MSR_IA32_MCx_STATUS(i));
if (!(status & MCi_STATUS_VAL))
continue; /* this bank has no valid telemetry */
/* For Intel Latest CPU CMCI/MCE Handler caller, we need to
* decide whether to clear bank by MCi_STATUS bit value such as
* OVER/UC/EN/PCC/S/AR
*/
if ( mc_need_clearbank_scan )
need_clear = mc_need_clearbank_scan(who, status);
/* If this is the first bank with valid MCA DATA, then
* try to reserve an entry from the urgent/nonurgent queue
* depending on whether we are called from an exception or
* a poller; this can fail (for example dom0 may not
* yet have consumed past telemetry). */
if (errcnt++ == 0) {
if ( (mctc = mctelem_reserve(which)) != NULL ) {
mci = mctelem_dataptr(mctc);
mcinfo_clear(mci);
mig = x86_mcinfo_reserve(mci, sizeof(*mig));
/* mc_info should at least hold up the global information */
ASSERT(mig);
mca_init_global(mc_flags, mig);
/* A hook here to get global extended msrs */
{
if (boot_cpu_data.x86_vendor ==
X86_VENDOR_INTEL)
intel_get_extended_msrs(mig, mci);
}
}
}
/* flag for uncorrected errors */
if (!uc && ((status & MCi_STATUS_UC) != 0))
uc = 1;
/* flag processor context corrupt */
if (!pcc && ((status & MCi_STATUS_PCC) != 0))
pcc = 1;
if (recover && uc)
/* uc = 1, recover = 1, we need not panic.
*/
recover = mc_recoverable_scan(status);
mca_init_bank(who, mci, i);
if (mc_callback_bank_extended)
mc_callback_bank_extended(mci, i, status);
/* By default, need_clear = 1 */
if (who != MCA_MCE_SCAN && need_clear)
/* Clear bank */
mcabank_clear(i);
else if ( who == MCA_MCE_SCAN && need_clear)
mcabanks_set(i, clear_bank);
wmb();
}
if (mig && errcnt > 0) {
if (pcc)
mig->mc_flags |= MC_FLAG_UNCORRECTABLE;
else if (uc)
mig->mc_flags |= MC_FLAG_RECOVERABLE;
else
mig->mc_flags |= MC_FLAG_CORRECTABLE;
}
if (sp) {
sp->errcnt = errcnt;
sp->ripv = (gstatus & MCG_STATUS_RIPV) != 0;
sp->eipv = (gstatus & MCG_STATUS_EIPV) != 0;
sp->uc = uc;
sp->pcc = pcc;
sp->recoverable = recover;
}
return mci != NULL ? mctc : NULL; /* may be NULL */
}
/* Shared #MC handler. */
void mcheck_cmn_handler(struct cpu_user_regs *regs, long error_code,
struct mca_banks *bankmask)
{
int xen_state_lost, dom0_state_lost, domU_state_lost;
struct vcpu *v = current;
struct domain *curdom = v->domain;
domid_t domid = curdom->domain_id;
int ctx_xen, ctx_dom0, ctx_domU;
uint32_t dom_state = DOM_NORMAL;
mctelem_cookie_t mctc = NULL;
struct mca_summary bs;
struct mc_info *mci = NULL;
int irqlocked = 0;
uint64_t gstatus;
int ripv;
/* This handler runs as interrupt gate. So IPIs from the
* polling service routine are defered until we're finished.
*/
/* Disable interrupts for the _vcpu_. It may not re-scheduled to
* another physical CPU. */
vcpu_schedule_lock_irq(v);
irqlocked = 1;
/* Read global status; if it does not indicate machine check
* in progress then bail as long as we have a valid ip to return to. */
gstatus = mca_rdmsr(MSR_IA32_MCG_STATUS);
ripv = ((gstatus & MCG_STATUS_RIPV) != 0);
if (!(gstatus & MCG_STATUS_MCIP) && ripv) {
add_taint(TAINT_MACHINE_CHECK); /* questionable */
vcpu_schedule_unlock_irq(v);
irqlocked = 0;
goto cmn_handler_done;
}
/* Go and grab error telemetry. We must choose whether to commit
* for logging or dismiss the cookie that is returned, and must not
* reference the cookie after that action.
*/
mctc = mcheck_mca_logout(MCA_MCE_HANDLER, bankmask, &bs, NULL);
if (mctc != NULL)
mci = (struct mc_info *)mctelem_dataptr(mctc);
/* Clear MCIP or another #MC will enter shutdown state */
gstatus &= ~MCG_STATUS_MCIP;
mca_wrmsr(MSR_IA32_MCG_STATUS, gstatus);
wmb();
/* If no valid errors and our stack is intact, we're done */
if (ripv && bs.errcnt == 0) {
vcpu_schedule_unlock_irq(v);
irqlocked = 0;
goto cmn_handler_done;
}
if (bs.uc || bs.pcc)
add_taint(TAINT_MACHINE_CHECK);
/* Machine check exceptions will usually be for UC and/or PCC errors,
* but it is possible to configure machine check for some classes
* of corrected error.
*
* UC errors could compromise any domain or the hypervisor
* itself - for example a cache writeback of modified data that
* turned out to be bad could be for data belonging to anyone, not
* just the current domain. In the absence of known data poisoning
* to prevent consumption of such bad data in the system we regard
* all UC errors as terminal. It may be possible to attempt some
* heuristics based on the address affected, which guests have
* mappings to that mfn etc.
*
* PCC errors apply to the current context.
*
* If MCG_STATUS indicates !RIPV then even a #MC that is not UC
* and not PCC is terminal - the return instruction pointer
* pushed onto the stack is bogus. If the interrupt context is
* the hypervisor or dom0 the game is over, otherwise we can
* limit the impact to a single domU but only if we trampoline
* somewhere safely - we can't return and unwind the stack.
* Since there is no trampoline in place we will treat !RIPV
* as terminal for any context.
*/
ctx_xen = SEG_PL(regs->cs) == 0;
ctx_dom0 = !ctx_xen && (domid == 0);
ctx_domU = !ctx_xen && !ctx_dom0;
xen_state_lost = bs.uc != 0 || (ctx_xen && (bs.pcc || !ripv)) ||
!ripv;
dom0_state_lost = bs.uc != 0 || (ctx_dom0 && (bs.pcc || !ripv));
domU_state_lost = bs.uc != 0 || (ctx_domU && (bs.pcc || !ripv));
if (xen_state_lost) {
/* Now we are going to panic anyway. Allow interrupts, so that
* printk on serial console can work. */
vcpu_schedule_unlock_irq(v);
irqlocked = 0;
printk("Terminal machine check exception occurred in "
"hypervisor context.\n");
/* If MCG_STATUS_EIPV indicates, the IP on the stack is related
* to the error then it makes sense to print a stack trace.
* That can be useful for more detailed error analysis and/or
* error case studies to figure out, if we can clear
* xen_impacted and kill a DomU instead
* (i.e. if a guest only control structure is affected, but then
* we must ensure the bad pages are not re-used again).
*/
if (bs.eipv & MCG_STATUS_EIPV) {
printk("MCE: Instruction Pointer is related to the "
"error, therefore print the execution state.\n");
show_execution_state(regs);
}
/* Commit the telemetry so that panic flow can find it. */
if (mctc != NULL) {
x86_mcinfo_dump(mci);
mctelem_commit(mctc);
}
mc_panic("Hypervisor state lost due to machine check "
"exception.\n");
/*NOTREACHED*/
}
/*
* Xen hypervisor state is intact. If dom0 state is lost then
* give it a chance to decide what to do if it has registered
* a handler for this event, otherwise panic.
*
* XXFM Could add some Solaris dom0 contract kill here?
*/
if (dom0_state_lost) {
if (dom0 && dom0->max_vcpus && dom0->vcpu[0] &&
guest_has_trap_callback(dom0, 0, TRAP_machine_check)) {
dom_state = DOM0_TRAP;
send_guest_trap(dom0, 0, TRAP_machine_check);
/* XXFM case of return with !ripv ??? */
} else {
/* Commit telemetry for panic flow. */
if (mctc != NULL) {
x86_mcinfo_dump(mci);
mctelem_commit(mctc);
}
mc_panic("Dom0 state lost due to machine check "
"exception\n");
/*NOTREACHED*/
}
}
/*
* If a domU has lost state then send it a trap if it has registered
* a handler, otherwise crash the domain.
* XXFM Revisit this functionality.
*/
if (domU_state_lost) {
if (guest_has_trap_callback(v->domain, v->vcpu_id,
TRAP_machine_check)) {
dom_state = DOMU_TRAP;
send_guest_trap(curdom, v->vcpu_id,
TRAP_machine_check);
} else {
dom_state = DOMU_KILLED;
/* Enable interrupts. This basically results in
* calling sti on the *physical* cpu. But after
* domain_crash() the vcpu pointer is invalid.
* Therefore, we must unlock the irqs before killing
* it. */
vcpu_schedule_unlock_irq(v);
irqlocked = 0;
/* DomU is impacted. Kill it and continue. */
domain_crash(curdom);
}
}
switch (dom_state) {
case DOM0_TRAP:
case DOMU_TRAP:
/* Enable interrupts. */
vcpu_schedule_unlock_irq(v);
irqlocked = 0;
/* guest softirqs and event callbacks are scheduled
* immediately after this handler exits. */
break;
case DOMU_KILLED:
/* Nothing to do here. */
break;
case DOM_NORMAL:
vcpu_schedule_unlock_irq(v);
irqlocked = 0;
break;
}
cmn_handler_done:
BUG_ON(irqlocked);
BUG_ON(!ripv);
if (bs.errcnt) {
/* Not panicing, so forward telemetry to dom0 now if it
* is interested. */
if (dom0_vmce_enabled()) {
if (mctc != NULL)
mctelem_commit(mctc);
send_guest_global_virq(dom0, VIRQ_MCA);
} else {
x86_mcinfo_dump(mci);
if (mctc != NULL)
mctelem_dismiss(mctc);
}
} else if (mctc != NULL) {
mctelem_dismiss(mctc);
}
}
