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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v5 03/11] x86/mce: handle host LMCE
A round of mce_softirq() may handle multiple deferred MCE's.
1/ If all of them are LMCE's, then mce_softirq() is called on one CPU
and should not wait for others.
2/ If at least one of them is non-local MCE, then mce_softirq()
should sync with other CPUs. mce_softirq() should check those two
cases and handle them accordingly.
Because mce_softirq() can be interrupted by MC# again, we should also
ensure the deferred MCE handling in mce_softirq() is immutable to the
change of the checking result.
A per-cpu list 'lmce_pending' is introduced to 'struct mc_telem_cpu_ctl'
along with the existing per-cpu list 'pending' for LMCE handling.
MC# handler mcheck_cmn_handler() ensures that
1/ if all deferred MCE's on a CPU are LMCE's, then all of their
telemetries will be only in 'lmce_pending' on that CPU;
2/ if at least one of deferred MCE on a CPU is not LMCE, then all
telemetries of deferred MCE's on that CPU will be only in
'pending' on that CPU.
Therefore, the non-empty of 'lmce_pending' can be used to determine
whether it's the former of the beginning two cases in MCE softirq
handler mce_softirq().
mce_softirq() atomically moves deferred MCE's from either list
'lmce_pending' on the current CPU or lists 'pending' on the current or
other CPUs to list 'processing' in the current CPU, and then handles
deferred MCE's in list 'processing'. New coming MC# before and after
the atomic move, which change the result of the check, do not change
whether MCE's in 'processing' are LMCE or not, so mce_softirq() can
still handle 'processing' according to the result of previous check.
Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
---
Changes in v5:
* Adapt for changes in Patch 2.
* Add comment in mctelem_defer() to explain why the two separate exchanges
togerther can be treated as atomic.
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
xen/arch/x86/cpu/mcheck/mcaction.c | 4 +-
xen/arch/x86/cpu/mcheck/mce.c | 68 ++++++++++++++----------
xen/arch/x86/cpu/mcheck/mce.h | 1 +
xen/arch/x86/cpu/mcheck/mctelem.c | 104 ++++++++++++++++++++++++++++++++++---
xen/arch/x86/cpu/mcheck/mctelem.h | 5 +-
xen/arch/x86/cpu/mcheck/x86_mca.h | 4 +-
6 files changed, 147 insertions(+), 39 deletions(-)
diff --git a/xen/arch/x86/cpu/mcheck/mcaction.c
b/xen/arch/x86/cpu/mcheck/mcaction.c
index dab9eac306..ca17d22bd8 100644
--- a/xen/arch/x86/cpu/mcheck/mcaction.c
+++ b/xen/arch/x86/cpu/mcheck/mcaction.c
@@ -96,7 +96,9 @@ mc_memerr_dhandler(struct mca_binfo *binfo,
bank->mc_addr = gfn << PAGE_SHIFT |
(bank->mc_addr & (PAGE_SIZE -1 ));
- if (fill_vmsr_data(bank, d, global->mc_gstatus,
+ /* TODO: support injecting LMCE */
+ if (fill_vmsr_data(bank, d,
+ global->mc_gstatus & ~MCG_STATUS_LMCE,
vmce_vcpuid == VMCE_INJECT_BROADCAST))
{
mce_printk(MCE_QUIET, "Fill vMCE# data for DOM%d "
diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index d247d6e198..0e17fb707a 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -387,6 +387,7 @@ mcheck_mca_logout(enum mca_source who, struct mca_banks
*bankmask,
sp->errcnt = errcnt;
sp->ripv = (gstatus & MCG_STATUS_RIPV) != 0;
sp->eipv = (gstatus & MCG_STATUS_EIPV) != 0;
+ sp->lmce = (gstatus & MCG_STATUS_LMCE) != 0;
sp->uc = uc;
sp->pcc = pcc;
sp->recoverable = recover;
@@ -454,6 +455,7 @@ void mcheck_cmn_handler(const struct cpu_user_regs *regs)
uint64_t gstatus;
mctelem_cookie_t mctc = NULL;
struct mca_summary bs;
+ bool wait, lmce;
mce_spin_lock(&mce_logout_lock);
@@ -462,6 +464,8 @@ void mcheck_cmn_handler(const struct cpu_user_regs *regs)
sizeof(long) * BITS_TO_LONGS(clear_bank->num));
}
mctc = mcheck_mca_logout(MCA_MCE_SCAN, bankmask, &bs, clear_bank);
+ lmce = bs.lmce;
+ wait = mce_broadcast && !lmce;
if (bs.errcnt) {
/*
@@ -470,7 +474,7 @@ void mcheck_cmn_handler(const struct cpu_user_regs *regs)
if (bs.uc || bs.pcc) {
add_taint(TAINT_MACHINE_CHECK);
if (mctc != NULL)
- mctelem_defer(mctc);
+ mctelem_defer(mctc, lmce);
/*
* For PCC=1 and can't be recovered, context is lost, so
* reboot now without clearing the banks, and deal with
@@ -497,16 +501,16 @@ void mcheck_cmn_handler(const struct cpu_user_regs *regs)
}
mce_spin_unlock(&mce_logout_lock);
- mce_barrier_enter(&mce_trap_bar, mce_broadcast);
+ mce_barrier_enter(&mce_trap_bar, wait);
if ( mctc != NULL && mce_urgent_action(regs, mctc))
cpumask_set_cpu(smp_processor_id(), &mce_fatal_cpus);
- mce_barrier_exit(&mce_trap_bar, mce_broadcast);
+ mce_barrier_exit(&mce_trap_bar, wait);
/*
* Wait until everybody has processed the trap.
*/
- mce_barrier_enter(&mce_trap_bar, mce_broadcast);
- if (atomic_read(&severity_cpu) == smp_processor_id())
+ mce_barrier_enter(&mce_trap_bar, wait);
+ if (lmce || atomic_read(&severity_cpu) == smp_processor_id())
{
/* According to SDM, if no error bank found on any cpus,
* something unexpected happening, we can't do any
@@ -524,16 +528,16 @@ void mcheck_cmn_handler(const struct cpu_user_regs *regs)
atomic_set(&found_error, 0);
atomic_set(&severity_cpu, -1);
}
- mce_barrier_exit(&mce_trap_bar, mce_broadcast);
+ mce_barrier_exit(&mce_trap_bar, wait);
/* Clear flags after above fatal check */
- mce_barrier_enter(&mce_trap_bar, mce_broadcast);
+ mce_barrier_enter(&mce_trap_bar, wait);
gstatus = mca_rdmsr(MSR_IA32_MCG_STATUS);
if ((gstatus & MCG_STATUS_MCIP) != 0) {
mce_printk(MCE_CRITICAL, "MCE: Clear MCIP@ last step");
mca_wrmsr(MSR_IA32_MCG_STATUS, 0);
}
- mce_barrier_exit(&mce_trap_bar, mce_broadcast);
+ mce_barrier_exit(&mce_trap_bar, wait);
raise_softirq(MACHINE_CHECK_SOFTIRQ);
}
@@ -1562,7 +1566,8 @@ static void mc_panic_dump(void)
dprintk(XENLOG_ERR, "Begin dump mc_info\n");
for_each_online_cpu(cpu)
- mctelem_process_deferred(cpu, x86_mcinfo_dump_panic);
+ mctelem_process_deferred(cpu, x86_mcinfo_dump_panic,
+ mctelem_has_deferred_lmce(cpu));
dprintk(XENLOG_ERR, "End dump mc_info, %x mcinfo dumped\n",
mcinfo_dumpped);
}
@@ -1700,38 +1705,45 @@ static void mce_softirq(void)
static atomic_t severity_cpu;
int cpu = smp_processor_id();
unsigned int workcpu;
+ bool lmce = mctelem_has_deferred_lmce(cpu);
+ bool wait = mce_broadcast && !lmce;
mce_printk(MCE_VERBOSE, "CPU%d enter softirq\n", cpu);
- mce_barrier_enter(&mce_inside_bar, mce_broadcast);
+ mce_barrier_enter(&mce_inside_bar, wait);
- /*
- * Everybody is here. Now let's see who gets to do the
- * recovery work. Right now we just see if there's a CPU
- * that did not have any problems, and pick that one.
- *
- * First, just set a default value: the last CPU who reaches this
- * will overwrite the value and become the default.
- */
-
- atomic_set(&severity_cpu, cpu);
+ if (!lmce) {
+ /*
+ * Everybody is here. Now let's see who gets to do the
+ * recovery work. Right now we just see if there's a CPU
+ * that did not have any problems, and pick that one.
+ *
+ * First, just set a default value: the last CPU who reaches this
+ * will overwrite the value and become the default.
+ */
- mce_barrier_enter(&mce_severity_bar, mce_broadcast);
- if (!mctelem_has_deferred(cpu))
atomic_set(&severity_cpu, cpu);
- mce_barrier_exit(&mce_severity_bar, mce_broadcast);
+
+ mce_barrier_enter(&mce_severity_bar, wait);
+ if (!mctelem_has_deferred(cpu))
+ atomic_set(&severity_cpu, cpu);
+ mce_barrier_exit(&mce_severity_bar, wait);
+ }
/* We choose severity_cpu for further processing */
- if (atomic_read(&severity_cpu) == cpu) {
+ if (lmce || atomic_read(&severity_cpu) == cpu) {
mce_printk(MCE_VERBOSE, "CPU%d handling errors\n", cpu);
/* Step1: Fill DOM0 LOG buffer, vMCE injection buffer and
* vMCE MSRs virtualization buffer
*/
- for_each_online_cpu(workcpu) {
- mctelem_process_deferred(workcpu, mce_delayed_action);
- }
+
+ if (lmce)
+ mctelem_process_deferred(cpu, mce_delayed_action, true);
+ else
+ for_each_online_cpu(workcpu)
+ mctelem_process_deferred(workcpu, mce_delayed_action, false);
/* Step2: Send Log to DOM0 through vIRQ */
if (dom0_vmce_enabled()) {
@@ -1740,7 +1752,7 @@ static void mce_softirq(void)
}
}
- mce_barrier_exit(&mce_inside_bar, mce_broadcast);
+ mce_barrier_exit(&mce_inside_bar, wait);
}
/* Machine Check owner judge algorithm:
diff --git a/xen/arch/x86/cpu/mcheck/mce.h b/xen/arch/x86/cpu/mcheck/mce.h
index 10e5cebf8b..4f13791948 100644
--- a/xen/arch/x86/cpu/mcheck/mce.h
+++ b/xen/arch/x86/cpu/mcheck/mce.h
@@ -109,6 +109,7 @@ struct mca_summary {
int eipv; /* meaningful on #MC */
bool uc; /* UC flag */
bool pcc; /* PCC flag */
+ bool lmce; /* LMCE flag (Intel only) */
bool recoverable; /* software error recoverable flag */
};
diff --git a/xen/arch/x86/cpu/mcheck/mctelem.c
b/xen/arch/x86/cpu/mcheck/mctelem.c
index 57abeab357..a2fb319ff8 100644
--- a/xen/arch/x86/cpu/mcheck/mctelem.c
+++ b/xen/arch/x86/cpu/mcheck/mctelem.c
@@ -109,8 +109,22 @@ struct mc_telem_cpu_ctl {
/*
* Per-CPU processing lists, used for deferred (softirq)
* processing of telemetry.
+ *
+ * The two pending lists @lmce_pending and @pending grow at
+ * the head in the reverse chronological order.
+ *
+ * @pending and @lmce_pending on the same CPU are mutually
+ * exclusive, i.e. deferred MCE on a CPU are either all in
+ * @lmce_pending or all in @pending. In the former case, all
+ * deferred MCE are LMCE. In the latter case, both LMCE and
+ * non-local MCE can be in @pending, and @pending contains at
+ * least one non-local MCE if it's not empty.
+ *
+ * Changes to @pending and @lmce_pending should be performed
+ * via mctelem_process_deferred() and mctelem_defer(), in order
+ * to guarantee the above mutual exclusivity.
*/
- struct mctelem_ent *pending;
+ struct mctelem_ent *pending, *lmce_pending;
struct mctelem_ent *processing;
};
static DEFINE_PER_CPU(struct mc_telem_cpu_ctl, mctctl);
@@ -131,26 +145,97 @@ static void mctelem_xchg_head(struct mctelem_ent **headp,
}
}
-
-void mctelem_defer(mctelem_cookie_t cookie)
+/**
+ * Append a telemetry of deferred MCE to a per-cpu pending list,
+ * either @pending or @lmce_pending, according to rules below:
+ * - if @pending is not empty, then the new telemetry will be
+ * appended to @pending;
+ * - if @pending is empty and the new telemetry is for a deferred
+ * LMCE, then the new telemetry will be appended to @lmce_pending;
+ * - if @pending is empty and the new telemetry is for a deferred
+ * non-local MCE, all existing telemetries in @lmce_pending will be
+ * moved to @pending and then the new telemetry will be appended to
+ * @pending.
+ *
+ * This function must be called with MCIP bit set, so that it does not
+ * need to worry about MC# re-occurring in this function.
+ *
+ * As a result, this function can preserve the mutual exclusivity
+ * between @pending and @lmce_pending (see their comments in struct
+ * mc_telem_cpu_ctl).
+ *
+ * Parameters:
+ * @cookie: telemetry of the deferred MCE
+ * @lmce: indicate whether the telemetry is for LMCE
+ */
+void mctelem_defer(mctelem_cookie_t cookie, bool lmce)
{
struct mctelem_ent *tep = COOKIE2MCTE(cookie);
-
- mctelem_xchg_head(&this_cpu(mctctl.pending), &tep->mcte_next, tep);
+ struct mc_telem_cpu_ctl *mctctl = &this_cpu(mctctl);
+
+ ASSERT(mctctl->pending == NULL || mctctl->lmce_pending == NULL);
+
+ if (mctctl->pending)
+ mctelem_xchg_head(&mctctl->pending, &tep->mcte_next, tep);
+ else if (lmce)
+ mctelem_xchg_head(&mctctl->lmce_pending, &tep->mcte_next, tep);
+ else {
+ /*
+ * LMCE is supported on Skylake-server and later CPUs, on
+ * which mce_broadcast is always true. Therefore, non-empty
+ * mctctl->lmce_pending in this branch implies a broadcasting
+ * MC# is being handled, every CPU is in the exception
+ * context, and no one is consuming mctctl->pending at this
+ * moment. As a result, the following two exchanges together
+ * can be treated as atomic.
+ */
+ if (mctctl->lmce_pending)
+ mctelem_xchg_head(&mctctl->lmce_pending,
+ &mctctl->pending, NULL);
+ mctelem_xchg_head(&mctctl->pending, &tep->mcte_next, tep);
+ }
}
+/**
+ * Move telemetries of deferred MCE from the per-cpu pending list on
+ * this or another CPU to the per-cpu processing list on this CPU, and
+ * then process all deferred MCE on the processing list.
+ *
+ * This function can be called with MCIP bit set (e.g. from MC#
+ * handler) or cleared (from MCE softirq handler). In the latter case,
+ * MC# may re-occur in this function.
+ *
+ * Parameters:
+ * @cpu: indicate the CPU where the pending list is
+ * @fn: the function to handle the deferred MCE
+ * @lmce: indicate which pending list on @cpu is handled
+ */
void mctelem_process_deferred(unsigned int cpu,
- int (*fn)(mctelem_cookie_t))
+ int (*fn)(mctelem_cookie_t),
+ bool lmce)
{
struct mctelem_ent *tep;
struct mctelem_ent *head, *prev;
+ struct mc_telem_cpu_ctl *mctctl = &per_cpu(mctctl, cpu);
int ret;
/*
* First, unhook the list of telemetry structures, and
* hook it up to the processing list head for this CPU.
+ *
+ * If @lmce is true and a non-local MC# occurs before the
+ * following atomic exchange, @lmce will not hold after
+ * resumption, because all telemetries in @lmce_pending on
+ * @cpu are moved to @pending on @cpu in mcheck_cmn_handler().
+ * In such a case, no telemetries will be handled in this
+ * function after resumption. Another round of MCE softirq,
+ * which was raised by above mcheck_cmn_handler(), will handle
+ * those moved telemetries in @pending on @cpu.
+ *
+ * If another MC# occurs after the following atomic exchange,
+ * it will be handled by another round of MCE softirq.
*/
- mctelem_xchg_head(&per_cpu(mctctl.pending, cpu),
+ mctelem_xchg_head(lmce ? &mctctl->lmce_pending : &mctctl->pending,
&this_cpu(mctctl.processing), NULL);
head = this_cpu(mctctl.processing);
@@ -194,6 +279,11 @@ bool mctelem_has_deferred(unsigned int cpu)
return false;
}
+bool mctelem_has_deferred_lmce(unsigned int cpu)
+{
+ return per_cpu(mctctl.lmce_pending, cpu) != NULL;
+}
+
/* Free an entry to its native free list; the entry must not be linked on
* any list.
*/
diff --git a/xen/arch/x86/cpu/mcheck/mctelem.h
b/xen/arch/x86/cpu/mcheck/mctelem.h
index 9fcde4f6b8..d4eba53ae0 100644
--- a/xen/arch/x86/cpu/mcheck/mctelem.h
+++ b/xen/arch/x86/cpu/mcheck/mctelem.h
@@ -67,9 +67,10 @@ extern void mctelem_dismiss(mctelem_cookie_t);
extern mctelem_cookie_t mctelem_consume_oldest_begin(mctelem_class_t);
extern void mctelem_consume_oldest_end(mctelem_cookie_t);
extern void mctelem_ack(mctelem_class_t, mctelem_cookie_t);
-extern void mctelem_defer(mctelem_cookie_t);
+extern void mctelem_defer(mctelem_cookie_t, bool lmce);
extern void mctelem_process_deferred(unsigned int,
- int (*)(mctelem_cookie_t));
+ int (*)(mctelem_cookie_t), bool lmce);
bool mctelem_has_deferred(unsigned int);
+bool mctelem_has_deferred_lmce(unsigned int cpu);
#endif
diff --git a/xen/arch/x86/cpu/mcheck/x86_mca.h
b/xen/arch/x86/cpu/mcheck/x86_mca.h
index 34d1921ce1..de03f829c3 100644
--- a/xen/arch/x86/cpu/mcheck/x86_mca.h
+++ b/xen/arch/x86/cpu/mcheck/x86_mca.h
@@ -42,7 +42,9 @@
#define MCG_STATUS_RIPV 0x0000000000000001ULL
#define MCG_STATUS_EIPV 0x0000000000000002ULL
#define MCG_STATUS_MCIP 0x0000000000000004ULL
-/* Bits 3-63 are reserved */
+#define MCG_STATUS_LMCE 0x0000000000000008ULL /* Intel specific */
+/* Bits 3-63 are reserved on CPU not supporting LMCE */
+/* Bits 4-63 are reserved on CPU supporting LMCE */
/* Bitfield of MSR_K8_MCi_STATUS registers */
/* MCA error code */
--
2.11.0
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