1 files changed, 377 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/book3s_hv_ras.c b/arch/powerpc/kvm/book3s_hv_ras.c
new file mode 100644
index 000000000..82be6d875
--- /dev/null
+++ b/arch/powerpc/kvm/book3s_hv_ras.c
@@ -0,0 +1,377 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright 2012 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
+ */
+
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <linux/kernel.h>
+#include <asm/lppaca.h>
+#include <asm/opal.h>
+#include <asm/mce.h>
+#include <asm/machdep.h>
+#include <asm/cputhreads.h>
+#include <asm/hmi.h>
+#include <asm/kvm_ppc.h>
+
+/* SRR1 bits for machine check on POWER7 */
+#define SRR1_MC_LDSTERR		(1ul << (63-42))
+#define SRR1_MC_IFETCH_SH	(63-45)
+#define SRR1_MC_IFETCH_MASK	0x7
+#define SRR1_MC_IFETCH_SLBPAR		2	/* SLB parity error */
+#define SRR1_MC_IFETCH_SLBMULTI		3	/* SLB multi-hit */
+#define SRR1_MC_IFETCH_SLBPARMULTI	4	/* SLB parity + multi-hit */
+#define SRR1_MC_IFETCH_TLBMULTI		5	/* I-TLB multi-hit */
+
+/* DSISR bits for machine check on POWER7 */
+#define DSISR_MC_DERAT_MULTI	0x800		/* D-ERAT multi-hit */
+#define DSISR_MC_TLB_MULTI	0x400		/* D-TLB multi-hit */
+#define DSISR_MC_SLB_PARITY	0x100		/* SLB parity error */
+#define DSISR_MC_SLB_MULTI	0x080		/* SLB multi-hit */
+#define DSISR_MC_SLB_PARMULTI	0x040		/* SLB parity + multi-hit */
+
+/* POWER7 SLB flush and reload */
+static void reload_slb(struct kvm_vcpu *vcpu)
+{
+	struct slb_shadow *slb;
+	unsigned long i, n;
+
+	/* First clear out SLB */
+	asm volatile("slbmte %0,%0; slbia" : : "r" (0));
+
+	/* Do they have an SLB shadow buffer registered? */
+	slb = vcpu->arch.slb_shadow.pinned_addr;
+	if (!slb)
+		return;
+
+	/* Sanity check */
+	n = min_t(u32, be32_to_cpu(slb->persistent), SLB_MIN_SIZE);
+	if ((void *) &slb->save_area[n] > vcpu->arch.slb_shadow.pinned_end)
+		return;
+
+	/* Load up the SLB from that */
+	for (i = 0; i < n; ++i) {
+		unsigned long rb = be64_to_cpu(slb->save_area[i].esid);
+		unsigned long rs = be64_to_cpu(slb->save_area[i].vsid);
+
+		rb = (rb & ~0xFFFul) | i;	/* insert entry number */
+		asm volatile("slbmte %0,%1" : : "r" (rs), "r" (rb));
+	}
+}
+
+/*
+ * On POWER7, see if we can handle a machine check that occurred inside
+ * the guest in real mode, without switching to the host partition.
+ */
+static long kvmppc_realmode_mc_power7(struct kvm_vcpu *vcpu)
+{
+	unsigned long srr1 = vcpu->arch.shregs.msr;
+	long handled = 1;
+
+	if (srr1 & SRR1_MC_LDSTERR) {
+		/* error on load/store */
+		unsigned long dsisr = vcpu->arch.shregs.dsisr;
+
+		if (dsisr & (DSISR_MC_SLB_PARMULTI | DSISR_MC_SLB_MULTI |
+			     DSISR_MC_SLB_PARITY | DSISR_MC_DERAT_MULTI)) {
+			/* flush and reload SLB; flushes D-ERAT too */
+			reload_slb(vcpu);
+			dsisr &= ~(DSISR_MC_SLB_PARMULTI | DSISR_MC_SLB_MULTI |
+				   DSISR_MC_SLB_PARITY | DSISR_MC_DERAT_MULTI);
+		}
+		if (dsisr & DSISR_MC_TLB_MULTI) {
+			tlbiel_all_lpid(vcpu->kvm->arch.radix);
+			dsisr &= ~DSISR_MC_TLB_MULTI;
+		}
+		/* Any other errors we don't understand? */
+		if (dsisr & 0xffffffffUL)
+			handled = 0;
+	}
+
+	switch ((srr1 >> SRR1_MC_IFETCH_SH) & SRR1_MC_IFETCH_MASK) {
+	case 0:
+		break;
+	case SRR1_MC_IFETCH_SLBPAR:
+	case SRR1_MC_IFETCH_SLBMULTI:
+	case SRR1_MC_IFETCH_SLBPARMULTI:
+		reload_slb(vcpu);
+		break;
+	case SRR1_MC_IFETCH_TLBMULTI:
+		tlbiel_all_lpid(vcpu->kvm->arch.radix);
+		break;
+	default:
+		handled = 0;
+	}
+
+	return handled;
+}
+
+void kvmppc_realmode_machine_check(struct kvm_vcpu *vcpu)
+{
+	struct machine_check_event mce_evt;
+	long handled;
+
+	if (vcpu->kvm->arch.fwnmi_enabled) {
+		/* FWNMI guests handle their own recovery */
+		handled = 0;
+	} else {
+		handled = kvmppc_realmode_mc_power7(vcpu);
+	}
+
+	/*
+	 * Now get the event and stash it in the vcpu struct so it can
+	 * be handled by the primary thread in virtual mode.  We can't
+	 * call machine_check_queue_event() here if we are running on
+	 * an offline secondary thread.
+	 */
+	if (get_mce_event(&mce_evt, MCE_EVENT_RELEASE)) {
+		if (handled && mce_evt.version == MCE_V1)
+			mce_evt.disposition = MCE_DISPOSITION_RECOVERED;
+	} else {
+		memset(&mce_evt, 0, sizeof(mce_evt));
+	}
+
+	vcpu->arch.mce_evt = mce_evt;
+}
+
+
+long kvmppc_p9_realmode_hmi_handler(struct kvm_vcpu *vcpu)
+{
+	struct kvmppc_vcore *vc = vcpu->arch.vcore;
+	long ret = 0;
+
+	/*
+	 * Unapply and clear the offset first. That way, if the TB was not
+	 * resynced then it will remain in host-offset, and if it was resynced
+	 * then it is brought into host-offset. Then the tb offset is
+	 * re-applied before continuing with the KVM exit.
+	 *
+	 * This way, we don't need to actually know whether not OPAL resynced
+	 * the timebase or do any of the complicated dance that the P7/8
+	 * path requires.
+	 */
+	if (vc->tb_offset_applied) {
+		u64 new_tb = mftb() - vc->tb_offset_applied;
+		mtspr(SPRN_TBU40, new_tb);
+		if ((mftb() & 0xffffff) < (new_tb & 0xffffff)) {
+			new_tb += 0x1000000;
+			mtspr(SPRN_TBU40, new_tb);
+		}
+		vc->tb_offset_applied = 0;
+	}
+
+	local_paca->hmi_irqs++;
+
+	if (hmi_handle_debugtrig(NULL) >= 0) {
+		ret = 1;
+		goto out;
+	}
+
+	if (ppc_md.hmi_exception_early)
+		ppc_md.hmi_exception_early(NULL);
+
+out:
+	if (vc->tb_offset) {
+		u64 new_tb = mftb() + vc->tb_offset;
+		mtspr(SPRN_TBU40, new_tb);
+		if ((mftb() & 0xffffff) < (new_tb & 0xffffff)) {
+			new_tb += 0x1000000;
+			mtspr(SPRN_TBU40, new_tb);
+		}
+		vc->tb_offset_applied = vc->tb_offset;
+	}
+
+	return ret;
+}
+
+/*
+ * The following subcore HMI handling is all only for pre-POWER9 CPUs.
+ */
+
+/* Check if dynamic split is in force and return subcore size accordingly. */
+static inline int kvmppc_cur_subcore_size(void)
+{
+	if (local_paca->kvm_hstate.kvm_split_mode)
+		return local_paca->kvm_hstate.kvm_split_mode->subcore_size;
+
+	return threads_per_subcore;
+}
+
+void kvmppc_subcore_enter_guest(void)
+{
+	int thread_id, subcore_id;
+
+	thread_id = cpu_thread_in_core(local_paca->paca_index);
+	subcore_id = thread_id / kvmppc_cur_subcore_size();
+
+	local_paca->sibling_subcore_state->in_guest[subcore_id] = 1;
+}
+EXPORT_SYMBOL_GPL(kvmppc_subcore_enter_guest);
+
+void kvmppc_subcore_exit_guest(void)
+{
+	int thread_id, subcore_id;
+
+	thread_id = cpu_thread_in_core(local_paca->paca_index);
+	subcore_id = thread_id / kvmppc_cur_subcore_size();
+
+	local_paca->sibling_subcore_state->in_guest[subcore_id] = 0;
+}
+EXPORT_SYMBOL_GPL(kvmppc_subcore_exit_guest);
+
+static bool kvmppc_tb_resync_required(void)
+{
+	if (test_and_set_bit(CORE_TB_RESYNC_REQ_BIT,
+				&local_paca->sibling_subcore_state->flags))
+		return false;
+
+	return true;
+}
+
+static void kvmppc_tb_resync_done(void)
+{
+	clear_bit(CORE_TB_RESYNC_REQ_BIT,
+			&local_paca->sibling_subcore_state->flags);
+}
+
+/*
+ * kvmppc_realmode_hmi_handler() is called only by primary thread during
+ * guest exit path.
+ *
+ * There are multiple reasons why HMI could occur, one of them is
+ * Timebase (TB) error. If this HMI is due to TB error, then TB would
+ * have been in stopped state. The opal hmi handler Will fix it and
+ * restore the TB value with host timebase value. For HMI caused due
+ * to non-TB errors, opal hmi handler will not touch/restore TB register
+ * and hence there won't be any change in TB value.
+ *
+ * Since we are not sure about the cause of this HMI, we can't be sure
+ * about the content of TB register whether it holds guest or host timebase
+ * value. Hence the idea is to resync the TB on every HMI, so that we
+ * know about the exact state of the TB value. Resync TB call will
+ * restore TB to host timebase.
+ *
+ * Things to consider:
+ * - On TB error, HMI interrupt is reported on all the threads of the core
+ *   that has encountered TB error irrespective of split-core mode.
+ * - The very first thread on the core that get chance to fix TB error
+ *   would rsync the TB with local chipTOD value.
+ * - The resync TB is a core level action i.e. it will sync all the TBs
+ *   in that core independent of split-core mode. This means if we trigger
+ *   TB sync from a thread from one subcore, it would affect TB values of
+ *   sibling subcores of the same core.
+ *
+ * All threads need to co-ordinate before making opal hmi handler.
+ * All threads will use sibling_subcore_state->in_guest[] (shared by all
+ * threads in the core) in paca which holds information about whether
+ * sibling subcores are in Guest mode or host mode. The in_guest[] array
+ * is of size MAX_SUBCORE_PER_CORE=4, indexed using subcore id to set/unset
+ * subcore status. Only primary threads from each subcore is responsible
+ * to set/unset its designated array element while entering/exiting the
+ * guset.
+ *
+ * After invoking opal hmi handler call, one of the thread (of entire core)
+ * will need to resync the TB. Bit 63 from subcore state bitmap flags
+ * (sibling_subcore_state->flags) will be used to co-ordinate between
+ * primary threads to decide who takes up the responsibility.
+ *
+ * This is what we do:
+ * - Primary thread from each subcore tries to set resync required bit[63]
+ *   of paca->sibling_subcore_state->flags.
+ * - The first primary thread that is able to set the flag takes the
+ *   responsibility of TB resync. (Let us call it as thread leader)
+ * - All other threads which are in host will call
+ *   wait_for_subcore_guest_exit() and wait for in_guest[0-3] from
+ *   paca->sibling_subcore_state to get cleared.
+ * - All the primary thread will clear its subcore status from subcore
+ *   state in_guest[] array respectively.
+ * - Once all primary threads clear in_guest[0-3], all of them will invoke
+ *   opal hmi handler.
+ * - Now all threads will wait for TB resync to complete by invoking
+ *   wait_for_tb_resync() except the thread leader.
+ * - Thread leader will do a TB resync by invoking opal_resync_timebase()
+ *   call and the it will clear the resync required bit.
+ * - All other threads will now come out of resync wait loop and proceed
+ *   with individual execution.
+ * - On return of this function, primary thread will signal all
+ *   secondary threads to proceed.
+ * - All secondary threads will eventually call opal hmi handler on
+ *   their exit path.
+ *
+ * Returns 1 if the timebase offset should be applied, 0 if not.
+ */
+
+long kvmppc_realmode_hmi_handler(void)
+{
+	bool resync_req;
+
+	local_paca->hmi_irqs++;
+
+	if (hmi_handle_debugtrig(NULL) >= 0)
+		return 1;
+
+	/*
+	 * By now primary thread has already completed guest->host
+	 * partition switch but haven't signaled secondaries yet.
+	 * All the secondary threads on this subcore is waiting
+	 * for primary thread to signal them to go ahead.
+	 *
+	 * For threads from subcore which isn't in guest, they all will
+	 * wait until all other subcores on this core exit the guest.
+	 *
+	 * Now set the resync required bit. If you are the first to
+	 * set this bit then kvmppc_tb_resync_required() function will
+	 * return true. For rest all other subcores
+	 * kvmppc_tb_resync_required() will return false.
+	 *
+	 * If resync_req == true, then this thread is responsible to
+	 * initiate TB resync after hmi handler has completed.
+	 * All other threads on this core will wait until this thread
+	 * clears the resync required bit flag.
+	 */
+	resync_req = kvmppc_tb_resync_required();
+
+	/* Reset the subcore status to indicate it has exited guest */
+	kvmppc_subcore_exit_guest();
+
+	/*
+	 * Wait for other subcores on this core to exit the guest.
+	 * All the primary threads and threads from subcore that are
+	 * not in guest will wait here until all subcores are out
+	 * of guest context.
+	 */
+	wait_for_subcore_guest_exit();
+
+	/*
+	 * At this point we are sure that primary threads from each
+	 * subcore on this core have completed guest->host partition
+	 * switch. Now it is safe to call HMI handler.
+	 */
+	if (ppc_md.hmi_exception_early)
+		ppc_md.hmi_exception_early(NULL);
+
+	/*
+	 * Check if this thread is responsible to resync TB.
+	 * All other threads will wait until this thread completes the
+	 * TB resync.
+	 */
+	if (resync_req) {
+		opal_resync_timebase();
+		/* Reset TB resync req bit */
+		kvmppc_tb_resync_done();
+	} else {
+		wait_for_tb_resync();
+	}
+
+	/*
+	 * Reset tb_offset_applied so the guest exit code won't try
+	 * to subtract the previous timebase offset from the timebase.
+	 */
+	if (local_paca->kvm_hstate.kvm_vcore)
+		local_paca->kvm_hstate.kvm_vcore->tb_offset_applied = 0;
+
+	return 0;
+}