linux-zen-server/arch/powerpc/kvm/book3s_hv_p9_entry.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kernel.h>
#include <linux/kvm_host.h>
#include <asm/asm-prototypes.h>
#include <asm/dbell.h>
#include <asm/ppc-opcode.h>

#include "book3s_hv.h"

static void load_spr_state(struct kvm_vcpu *vcpu,
				struct p9_host_os_sprs *host_os_sprs)
{
	/* TAR is very fast */
	mtspr(SPRN_TAR, vcpu->arch.tar);

#ifdef CONFIG_ALTIVEC
	if (cpu_has_feature(CPU_FTR_ALTIVEC) &&
	    current->thread.vrsave != vcpu->arch.vrsave)
		mtspr(SPRN_VRSAVE, vcpu->arch.vrsave);
#endif

	if (vcpu->arch.hfscr & HFSCR_EBB) {
		if (current->thread.ebbhr != vcpu->arch.ebbhr)
			mtspr(SPRN_EBBHR, vcpu->arch.ebbhr);
		if (current->thread.ebbrr != vcpu->arch.ebbrr)
			mtspr(SPRN_EBBRR, vcpu->arch.ebbrr);
		if (current->thread.bescr != vcpu->arch.bescr)
			mtspr(SPRN_BESCR, vcpu->arch.bescr);
	}

	if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
			current->thread.tidr != vcpu->arch.tid)
		mtspr(SPRN_TIDR, vcpu->arch.tid);
	if (host_os_sprs->iamr != vcpu->arch.iamr)
		mtspr(SPRN_IAMR, vcpu->arch.iamr);
	if (host_os_sprs->amr != vcpu->arch.amr)
		mtspr(SPRN_AMR, vcpu->arch.amr);
	if (vcpu->arch.uamor != 0)
		mtspr(SPRN_UAMOR, vcpu->arch.uamor);
	if (current->thread.fscr != vcpu->arch.fscr)
		mtspr(SPRN_FSCR, vcpu->arch.fscr);
	if (current->thread.dscr != vcpu->arch.dscr)
		mtspr(SPRN_DSCR, vcpu->arch.dscr);
	if (vcpu->arch.pspb != 0)
		mtspr(SPRN_PSPB, vcpu->arch.pspb);

	/*
	 * DAR, DSISR, and for nested HV, SPRGs must be set with MSR[RI]
	 * clear (or hstate set appropriately to catch those registers
	 * being clobbered if we take a MCE or SRESET), so those are done
	 * later.
	 */

	if (!(vcpu->arch.ctrl & 1))
		mtspr(SPRN_CTRLT, 0);
}

static void store_spr_state(struct kvm_vcpu *vcpu)
{
	vcpu->arch.tar = mfspr(SPRN_TAR);

#ifdef CONFIG_ALTIVEC
	if (cpu_has_feature(CPU_FTR_ALTIVEC))
		vcpu->arch.vrsave = mfspr(SPRN_VRSAVE);
#endif

	if (vcpu->arch.hfscr & HFSCR_EBB) {
		vcpu->arch.ebbhr = mfspr(SPRN_EBBHR);
		vcpu->arch.ebbrr = mfspr(SPRN_EBBRR);
		vcpu->arch.bescr = mfspr(SPRN_BESCR);
	}

	if (cpu_has_feature(CPU_FTR_P9_TIDR))
		vcpu->arch.tid = mfspr(SPRN_TIDR);
	vcpu->arch.iamr = mfspr(SPRN_IAMR);
	vcpu->arch.amr = mfspr(SPRN_AMR);
	vcpu->arch.uamor = mfspr(SPRN_UAMOR);
	vcpu->arch.fscr = mfspr(SPRN_FSCR);
	vcpu->arch.dscr = mfspr(SPRN_DSCR);
	vcpu->arch.pspb = mfspr(SPRN_PSPB);

	vcpu->arch.ctrl = mfspr(SPRN_CTRLF);
}

/* Returns true if current MSR and/or guest MSR may have changed */
bool load_vcpu_state(struct kvm_vcpu *vcpu,
		     struct p9_host_os_sprs *host_os_sprs)
{
	bool ret = false;

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
	if (cpu_has_feature(CPU_FTR_TM) ||
	    cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) {
		unsigned long guest_msr = vcpu->arch.shregs.msr;
		if (MSR_TM_ACTIVE(guest_msr)) {
			kvmppc_restore_tm_hv(vcpu, guest_msr, true);
			ret = true;
		} else if (vcpu->arch.hfscr & HFSCR_TM) {
			mtspr(SPRN_TEXASR, vcpu->arch.texasr);
			mtspr(SPRN_TFHAR, vcpu->arch.tfhar);
			mtspr(SPRN_TFIAR, vcpu->arch.tfiar);
		}
	}
#endif

	load_spr_state(vcpu, host_os_sprs);

	load_fp_state(&vcpu->arch.fp);
#ifdef CONFIG_ALTIVEC
	load_vr_state(&vcpu->arch.vr);
#endif

	return ret;
}
EXPORT_SYMBOL_GPL(load_vcpu_state);

void store_vcpu_state(struct kvm_vcpu *vcpu)
{
	store_spr_state(vcpu);

	store_fp_state(&vcpu->arch.fp);
#ifdef CONFIG_ALTIVEC
	store_vr_state(&vcpu->arch.vr);
#endif

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
	if (cpu_has_feature(CPU_FTR_TM) ||
	    cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) {
		unsigned long guest_msr = vcpu->arch.shregs.msr;
		if (MSR_TM_ACTIVE(guest_msr)) {
			kvmppc_save_tm_hv(vcpu, guest_msr, true);
		} else if (vcpu->arch.hfscr & HFSCR_TM) {
			vcpu->arch.texasr = mfspr(SPRN_TEXASR);
			vcpu->arch.tfhar = mfspr(SPRN_TFHAR);
			vcpu->arch.tfiar = mfspr(SPRN_TFIAR);

			if (!vcpu->arch.nested) {
				vcpu->arch.load_tm++; /* see load_ebb comment */
				if (!vcpu->arch.load_tm)
					vcpu->arch.hfscr &= ~HFSCR_TM;
			}
		}
	}
#endif
}
EXPORT_SYMBOL_GPL(store_vcpu_state);

void save_p9_host_os_sprs(struct p9_host_os_sprs *host_os_sprs)
{
	host_os_sprs->iamr = mfspr(SPRN_IAMR);
	host_os_sprs->amr = mfspr(SPRN_AMR);
}
EXPORT_SYMBOL_GPL(save_p9_host_os_sprs);

/* vcpu guest regs must already be saved */
void restore_p9_host_os_sprs(struct kvm_vcpu *vcpu,
			     struct p9_host_os_sprs *host_os_sprs)
{
	/*
	 * current->thread.xxx registers must all be restored to host
	 * values before a potential context switch, otherwise the context
	 * switch itself will overwrite current->thread.xxx with the values
	 * from the guest SPRs.
	 */

	mtspr(SPRN_SPRG_VDSO_WRITE, local_paca->sprg_vdso);

	if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
			current->thread.tidr != vcpu->arch.tid)
		mtspr(SPRN_TIDR, current->thread.tidr);
	if (host_os_sprs->iamr != vcpu->arch.iamr)
		mtspr(SPRN_IAMR, host_os_sprs->iamr);
	if (vcpu->arch.uamor != 0)
		mtspr(SPRN_UAMOR, 0);
	if (host_os_sprs->amr != vcpu->arch.amr)
		mtspr(SPRN_AMR, host_os_sprs->amr);
	if (current->thread.fscr != vcpu->arch.fscr)
		mtspr(SPRN_FSCR, current->thread.fscr);
	if (current->thread.dscr != vcpu->arch.dscr)
		mtspr(SPRN_DSCR, current->thread.dscr);
	if (vcpu->arch.pspb != 0)
		mtspr(SPRN_PSPB, 0);

	/* Save guest CTRL register, set runlatch to 1 */
	if (!(vcpu->arch.ctrl & 1))
		mtspr(SPRN_CTRLT, 1);

#ifdef CONFIG_ALTIVEC
	if (cpu_has_feature(CPU_FTR_ALTIVEC) &&
	    vcpu->arch.vrsave != current->thread.vrsave)
		mtspr(SPRN_VRSAVE, current->thread.vrsave);
#endif
	if (vcpu->arch.hfscr & HFSCR_EBB) {
		if (vcpu->arch.bescr != current->thread.bescr)
			mtspr(SPRN_BESCR, current->thread.bescr);
		if (vcpu->arch.ebbhr != current->thread.ebbhr)
			mtspr(SPRN_EBBHR, current->thread.ebbhr);
		if (vcpu->arch.ebbrr != current->thread.ebbrr)
			mtspr(SPRN_EBBRR, current->thread.ebbrr);

		if (!vcpu->arch.nested) {
			/*
			 * This is like load_fp in context switching, turn off
			 * the facility after it wraps the u8 to try avoiding
			 * saving and restoring the registers each partition
			 * switch.
			 */
			vcpu->arch.load_ebb++;
			if (!vcpu->arch.load_ebb)
				vcpu->arch.hfscr &= ~HFSCR_EBB;
		}
	}

	if (vcpu->arch.tar != current->thread.tar)
		mtspr(SPRN_TAR, current->thread.tar);
}
EXPORT_SYMBOL_GPL(restore_p9_host_os_sprs);

#ifdef CONFIG_KVM_BOOK3S_HV_P9_TIMING
void accumulate_time(struct kvm_vcpu *vcpu, struct kvmhv_tb_accumulator *next)
{
	struct kvmppc_vcore *vc = vcpu->arch.vcore;
	struct kvmhv_tb_accumulator *curr;
	u64 tb = mftb() - vc->tb_offset_applied;
	u64 prev_tb;
	u64 delta;
	u64 seq;

	curr = vcpu->arch.cur_activity;
	vcpu->arch.cur_activity = next;
	prev_tb = vcpu->arch.cur_tb_start;
	vcpu->arch.cur_tb_start = tb;

	if (!curr)
		return;

	delta = tb - prev_tb;

	seq = curr->seqcount;
	curr->seqcount = seq + 1;
	smp_wmb();
	curr->tb_total += delta;
	if (seq == 0 || delta < curr->tb_min)
		curr->tb_min = delta;
	if (delta > curr->tb_max)
		curr->tb_max = delta;
	smp_wmb();
	curr->seqcount = seq + 2;
}
EXPORT_SYMBOL_GPL(accumulate_time);
#endif

static inline u64 mfslbv(unsigned int idx)
{
	u64 slbev;

	asm volatile("slbmfev  %0,%1" : "=r" (slbev) : "r" (idx));

	return slbev;
}

static inline u64 mfslbe(unsigned int idx)
{
	u64 slbee;

	asm volatile("slbmfee  %0,%1" : "=r" (slbee) : "r" (idx));

	return slbee;
}

static inline void mtslb(u64 slbee, u64 slbev)
{
	asm volatile("slbmte %0,%1" :: "r" (slbev), "r" (slbee));
}

static inline void clear_slb_entry(unsigned int idx)
{
	mtslb(idx, 0);
}

static inline void slb_clear_invalidate_partition(void)
{
	clear_slb_entry(0);
	asm volatile(PPC_SLBIA(6));
}

/*
 * Malicious or buggy radix guests may have inserted SLB entries
 * (only 0..3 because radix always runs with UPRT=1), so these must
 * be cleared here to avoid side-channels. slbmte is used rather
 * than slbia, as it won't clear cached translations.
 */
static void radix_clear_slb(void)
{
	int i;

	for (i = 0; i < 4; i++)
		clear_slb_entry(i);
}

static void switch_mmu_to_guest_radix(struct kvm *kvm, struct kvm_vcpu *vcpu, u64 lpcr)
{
	struct kvm_nested_guest *nested = vcpu->arch.nested;
	u32 lpid;
	u32 pid;

	lpid = nested ? nested->shadow_lpid : kvm->arch.lpid;
	pid = vcpu->arch.pid;

	/*
	 * Prior memory accesses to host PID Q3 must be completed before we
	 * start switching, and stores must be drained to avoid not-my-LPAR
	 * logic (see switch_mmu_to_host).
	 */
	asm volatile("hwsync" ::: "memory");
	isync();
	mtspr(SPRN_LPID, lpid);
	mtspr(SPRN_LPCR, lpcr);
	mtspr(SPRN_PID, pid);
	/*
	 * isync not required here because we are HRFID'ing to guest before
	 * any guest context access, which is context synchronising.
	 */
}

static void switch_mmu_to_guest_hpt(struct kvm *kvm, struct kvm_vcpu *vcpu, u64 lpcr)
{
	u32 lpid;
	u32 pid;
	int i;

	lpid = kvm->arch.lpid;
	pid = vcpu->arch.pid;

	/*
	 * See switch_mmu_to_guest_radix. ptesync should not be required here
	 * even if the host is in HPT mode because speculative accesses would
	 * not cause RC updates (we are in real mode).
	 */
	asm volatile("hwsync" ::: "memory");
	isync();
	mtspr(SPRN_LPID, lpid);
	mtspr(SPRN_LPCR, lpcr);
	mtspr(SPRN_PID, pid);

	for (i = 0; i < vcpu->arch.slb_max; i++)
		mtslb(vcpu->arch.slb[i].orige, vcpu->arch.slb[i].origv);
	/*
	 * isync not required here, see switch_mmu_to_guest_radix.
	 */
}

static void switch_mmu_to_host(struct kvm *kvm, u32 pid)
{
	u32 lpid = kvm->arch.host_lpid;
	u64 lpcr = kvm->arch.host_lpcr;

	/*
	 * The guest has exited, so guest MMU context is no longer being
	 * non-speculatively accessed, but a hwsync is needed before the
	 * mtLPIDR / mtPIDR switch, in order to ensure all stores are drained,
	 * so the not-my-LPAR tlbie logic does not overlook them.
	 */
	asm volatile("hwsync" ::: "memory");
	isync();
	mtspr(SPRN_PID, pid);
	mtspr(SPRN_LPID, lpid);
	mtspr(SPRN_LPCR, lpcr);
	/*
	 * isync is not required after the switch, because mtmsrd with L=0
	 * is performed after this switch, which is context synchronising.
	 */

	if (!radix_enabled())
		slb_restore_bolted_realmode();
}

static void save_clear_host_mmu(struct kvm *kvm)
{
	if (!radix_enabled()) {
		/*
		 * Hash host could save and restore host SLB entries to
		 * reduce SLB fault overheads of VM exits, but for now the
		 * existing code clears all entries and restores just the
		 * bolted ones when switching back to host.
		 */
		slb_clear_invalidate_partition();
	}
}

static void save_clear_guest_mmu(struct kvm *kvm, struct kvm_vcpu *vcpu)
{
	if (kvm_is_radix(kvm)) {
		radix_clear_slb();
	} else {
		int i;
		int nr = 0;

		/*
		 * This must run before switching to host (radix host can't
		 * access all SLBs).
		 */
		for (i = 0; i < vcpu->arch.slb_nr; i++) {
			u64 slbee, slbev;

			slbee = mfslbe(i);
			if (slbee & SLB_ESID_V) {
				slbev = mfslbv(i);
				vcpu->arch.slb[nr].orige = slbee | i;
				vcpu->arch.slb[nr].origv = slbev;
				nr++;
			}
		}
		vcpu->arch.slb_max = nr;
		slb_clear_invalidate_partition();
	}
}

static void flush_guest_tlb(struct kvm *kvm)
{
	unsigned long rb, set;

	rb = PPC_BIT(52);	/* IS = 2 */
	if (kvm_is_radix(kvm)) {
		/* R=1 PRS=1 RIC=2 */
		asm volatile(PPC_TLBIEL(%0, %4, %3, %2, %1)
			     : : "r" (rb), "i" (1), "i" (1), "i" (2),
			       "r" (0) : "memory");
		for (set = 1; set < kvm->arch.tlb_sets; ++set) {
			rb += PPC_BIT(51);	/* increment set number */
			/* R=1 PRS=1 RIC=0 */
			asm volatile(PPC_TLBIEL(%0, %4, %3, %2, %1)
				     : : "r" (rb), "i" (1), "i" (1), "i" (0),
				       "r" (0) : "memory");
		}
		asm volatile("ptesync": : :"memory");
		// POWER9 congruence-class TLBIEL leaves ERAT. Flush it now.
		asm volatile(PPC_RADIX_INVALIDATE_ERAT_GUEST : : :"memory");
	} else {
		for (set = 0; set < kvm->arch.tlb_sets; ++set) {
			/* R=0 PRS=0 RIC=0 */
			asm volatile(PPC_TLBIEL(%0, %4, %3, %2, %1)
				     : : "r" (rb), "i" (0), "i" (0), "i" (0),
				       "r" (0) : "memory");
			rb += PPC_BIT(51);	/* increment set number */
		}
		asm volatile("ptesync": : :"memory");
		// POWER9 congruence-class TLBIEL leaves ERAT. Flush it now.
		asm volatile(PPC_ISA_3_0_INVALIDATE_ERAT : : :"memory");
	}
}

static void check_need_tlb_flush(struct kvm *kvm, int pcpu,
				 struct kvm_nested_guest *nested)
{
	cpumask_t *need_tlb_flush;
	bool all_set = true;
	int i;

	if (nested)
		need_tlb_flush = &nested->need_tlb_flush;
	else
		need_tlb_flush = &kvm->arch.need_tlb_flush;

	if (likely(!cpumask_test_cpu(pcpu, need_tlb_flush)))
		return;

	/*
	 * Individual threads can come in here, but the TLB is shared between
	 * the 4 threads in a core, hence invalidating on one thread
	 * invalidates for all, so only invalidate the first time (if all bits
	 * were set.  The others must still execute a ptesync.
	 *
	 * If a race occurs and two threads do the TLB flush, that is not a
	 * problem, just sub-optimal.
	 */
	for (i = cpu_first_tlb_thread_sibling(pcpu);
			i <= cpu_last_tlb_thread_sibling(pcpu);
			i += cpu_tlb_thread_sibling_step()) {
		if (!cpumask_test_cpu(i, need_tlb_flush)) {
			all_set = false;
			break;
		}
	}
	if (all_set)
		flush_guest_tlb(kvm);
	else
		asm volatile("ptesync" ::: "memory");

	/* Clear the bit after the TLB flush */
	cpumask_clear_cpu(pcpu, need_tlb_flush);
}

unsigned long kvmppc_msr_hard_disable_set_facilities(struct kvm_vcpu *vcpu, unsigned long msr)
{
	unsigned long msr_needed = 0;

	msr &= ~MSR_EE;

	/* MSR bits may have been cleared by context switch so must recheck */
	if (IS_ENABLED(CONFIG_PPC_FPU))
		msr_needed |= MSR_FP;
	if (cpu_has_feature(CPU_FTR_ALTIVEC))
		msr_needed |= MSR_VEC;
	if (cpu_has_feature(CPU_FTR_VSX))
		msr_needed |= MSR_VSX;
	if ((cpu_has_feature(CPU_FTR_TM) ||
	    cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) &&
			(vcpu->arch.hfscr & HFSCR_TM))
		msr_needed |= MSR_TM;

	/*
	 * This could be combined with MSR[RI] clearing, but that expands
	 * the unrecoverable window. It would be better to cover unrecoverable
	 * with KVM bad interrupt handling rather than use MSR[RI] at all.
	 *
	 * Much more difficult and less worthwhile to combine with IR/DR
	 * disable.
	 */
	if ((msr & msr_needed) != msr_needed) {
		msr |= msr_needed;
		__mtmsrd(msr, 0);
	} else {
		__hard_irq_disable();
	}
	local_paca->irq_happened |= PACA_IRQ_HARD_DIS;

	return msr;
}
EXPORT_SYMBOL_GPL(kvmppc_msr_hard_disable_set_facilities);

int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpcr, u64 *tb)
{
	struct p9_host_os_sprs host_os_sprs;
	struct kvm *kvm = vcpu->kvm;
	struct kvm_nested_guest *nested = vcpu->arch.nested;
	struct kvmppc_vcore *vc = vcpu->arch.vcore;
	s64 hdec, dec;
	u64 purr, spurr;
	u64 *exsave;
	int trap;
	unsigned long msr;
	unsigned long host_hfscr;
	unsigned long host_ciabr;
	unsigned long host_dawr0;
	unsigned long host_dawrx0;
	unsigned long host_psscr;
	unsigned long host_hpsscr;
	unsigned long host_pidr;
	unsigned long host_dawr1;
	unsigned long host_dawrx1;
	unsigned long dpdes;

	hdec = time_limit - *tb;
	if (hdec < 0)
		return BOOK3S_INTERRUPT_HV_DECREMENTER;

	WARN_ON_ONCE(vcpu->arch.shregs.msr & MSR_HV);
	WARN_ON_ONCE(!(vcpu->arch.shregs.msr & MSR_ME));

	vcpu->arch.ceded = 0;

	/* Save MSR for restore, with EE clear. */
	msr = mfmsr() & ~MSR_EE;

	host_hfscr = mfspr(SPRN_HFSCR);
	host_ciabr = mfspr(SPRN_CIABR);
	host_psscr = mfspr(SPRN_PSSCR_PR);
	if (cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST))
		host_hpsscr = mfspr(SPRN_PSSCR);
	host_pidr = mfspr(SPRN_PID);

	if (dawr_enabled()) {
		host_dawr0 = mfspr(SPRN_DAWR0);
		host_dawrx0 = mfspr(SPRN_DAWRX0);
		if (cpu_has_feature(CPU_FTR_DAWR1)) {
			host_dawr1 = mfspr(SPRN_DAWR1);
			host_dawrx1 = mfspr(SPRN_DAWRX1);
		}
	}

	local_paca->kvm_hstate.host_purr = mfspr(SPRN_PURR);
	local_paca->kvm_hstate.host_spurr = mfspr(SPRN_SPURR);

	save_p9_host_os_sprs(&host_os_sprs);

	msr = kvmppc_msr_hard_disable_set_facilities(vcpu, msr);
	if (lazy_irq_pending()) {
		trap = 0;
		goto out;
	}

	if (unlikely(load_vcpu_state(vcpu, &host_os_sprs)))
		msr = mfmsr(); /* MSR may have been updated */

	if (vc->tb_offset) {
		u64 new_tb = *tb + vc->tb_offset;
		mtspr(SPRN_TBU40, new_tb);
		if ((mftb() & 0xffffff) < (new_tb & 0xffffff)) {
			new_tb += 0x1000000;
			mtspr(SPRN_TBU40, new_tb);
		}
		*tb = new_tb;
		vc->tb_offset_applied = vc->tb_offset;
	}

	mtspr(SPRN_VTB, vc->vtb);
	mtspr(SPRN_PURR, vcpu->arch.purr);
	mtspr(SPRN_SPURR, vcpu->arch.spurr);

	if (vc->pcr)
		mtspr(SPRN_PCR, vc->pcr | PCR_MASK);
	if (vcpu->arch.doorbell_request) {
		vcpu->arch.doorbell_request = 0;
		mtspr(SPRN_DPDES, 1);
	}

	if (dawr_enabled()) {
		if (vcpu->arch.dawr0 != host_dawr0)
			mtspr(SPRN_DAWR0, vcpu->arch.dawr0);
		if (vcpu->arch.dawrx0 != host_dawrx0)
			mtspr(SPRN_DAWRX0, vcpu->arch.dawrx0);
		if (cpu_has_feature(CPU_FTR_DAWR1)) {
			if (vcpu->arch.dawr1 != host_dawr1)
				mtspr(SPRN_DAWR1, vcpu->arch.dawr1);
			if (vcpu->arch.dawrx1 != host_dawrx1)
				mtspr(SPRN_DAWRX1, vcpu->arch.dawrx1);
		}
	}
	if (vcpu->arch.ciabr != host_ciabr)
		mtspr(SPRN_CIABR, vcpu->arch.ciabr);


	if (cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) {
		mtspr(SPRN_PSSCR, vcpu->arch.psscr | PSSCR_EC |
		      (local_paca->kvm_hstate.fake_suspend << PSSCR_FAKE_SUSPEND_LG));
	} else {
		if (vcpu->arch.psscr != host_psscr)
			mtspr(SPRN_PSSCR_PR, vcpu->arch.psscr);
	}

	mtspr(SPRN_HFSCR, vcpu->arch.hfscr);

	mtspr(SPRN_HSRR0, vcpu->arch.regs.nip);
	mtspr(SPRN_HSRR1, (vcpu->arch.shregs.msr & ~MSR_HV) | MSR_ME);

	/*
	 * On POWER9 DD2.1 and below, sometimes on a Hypervisor Data Storage
	 * Interrupt (HDSI) the HDSISR is not be updated at all.
	 *
	 * To work around this we put a canary value into the HDSISR before
	 * returning to a guest and then check for this canary when we take a
	 * HDSI. If we find the canary on a HDSI, we know the hardware didn't
	 * update the HDSISR. In this case we return to the guest to retake the
	 * HDSI which should correctly update the HDSISR the second time HDSI
	 * entry.
	 *
	 * The "radix prefetch bug" test can be used to test for this bug, as
	 * it also exists fo DD2.1 and below.
	 */
	if (cpu_has_feature(CPU_FTR_P9_RADIX_PREFETCH_BUG))
		mtspr(SPRN_HDSISR, HDSISR_CANARY);

	mtspr(SPRN_SPRG0, vcpu->arch.shregs.sprg0);
	mtspr(SPRN_SPRG1, vcpu->arch.shregs.sprg1);
	mtspr(SPRN_SPRG2, vcpu->arch.shregs.sprg2);
	mtspr(SPRN_SPRG3, vcpu->arch.shregs.sprg3);

	/*
	 * It might be preferable to load_vcpu_state here, in order to get the
	 * GPR/FP register loads executing in parallel with the previous mtSPR
	 * instructions, but for now that can't be done because the TM handling
	 * in load_vcpu_state can change some SPRs and vcpu state (nip, msr).
	 * But TM could be split out if this would be a significant benefit.
	 */

	/*
	 * MSR[RI] does not need to be cleared (and is not, for radix guests
	 * with no prefetch bug), because in_guest is set. If we take a SRESET
	 * or MCE with in_guest set but still in HV mode, then
	 * kvmppc_p9_bad_interrupt handles the interrupt, which effectively
	 * clears MSR[RI] and doesn't return.
	 */
	WRITE_ONCE(local_paca->kvm_hstate.in_guest, KVM_GUEST_MODE_HV_P9);
	barrier(); /* Open in_guest critical section */

	/*
	 * Hash host, hash guest, or radix guest with prefetch bug, all have
	 * to disable the MMU before switching to guest MMU state.
	 */
	if (!radix_enabled() || !kvm_is_radix(kvm) ||
			cpu_has_feature(CPU_FTR_P9_RADIX_PREFETCH_BUG))
		__mtmsrd(msr & ~(MSR_IR|MSR_DR|MSR_RI), 0);

	save_clear_host_mmu(kvm);

	if (kvm_is_radix(kvm))
		switch_mmu_to_guest_radix(kvm, vcpu, lpcr);
	else
		switch_mmu_to_guest_hpt(kvm, vcpu, lpcr);

	/* TLBIEL uses LPID=LPIDR, so run this after setting guest LPID */
	check_need_tlb_flush(kvm, vc->pcpu, nested);

	/*
	 * P9 suppresses the HDEC exception when LPCR[HDICE] = 0,
	 * so set guest LPCR (with HDICE) before writing HDEC.
	 */
	mtspr(SPRN_HDEC, hdec);

	mtspr(SPRN_DEC, vcpu->arch.dec_expires - *tb);

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
tm_return_to_guest:
#endif
	mtspr(SPRN_DAR, vcpu->arch.shregs.dar);
	mtspr(SPRN_DSISR, vcpu->arch.shregs.dsisr);
	mtspr(SPRN_SRR0, vcpu->arch.shregs.srr0);
	mtspr(SPRN_SRR1, vcpu->arch.shregs.srr1);

	switch_pmu_to_guest(vcpu, &host_os_sprs);
	accumulate_time(vcpu, &vcpu->arch.in_guest);

	kvmppc_p9_enter_guest(vcpu);

	accumulate_time(vcpu, &vcpu->arch.guest_exit);
	switch_pmu_to_host(vcpu, &host_os_sprs);

	/* XXX: Could get these from r11/12 and paca exsave instead */
	vcpu->arch.shregs.srr0 = mfspr(SPRN_SRR0);
	vcpu->arch.shregs.srr1 = mfspr(SPRN_SRR1);
	vcpu->arch.shregs.dar = mfspr(SPRN_DAR);
	vcpu->arch.shregs.dsisr = mfspr(SPRN_DSISR);

	/* 0x2 bit for HSRR is only used by PR and P7/8 HV paths, clear it */
	trap = local_paca->kvm_hstate.scratch0 & ~0x2;

	if (likely(trap > BOOK3S_INTERRUPT_MACHINE_CHECK))
		exsave = local_paca->exgen;
	else if (trap == BOOK3S_INTERRUPT_SYSTEM_RESET)
		exsave = local_paca->exnmi;
	else /* trap == 0x200 */
		exsave = local_paca->exmc;

	vcpu->arch.regs.gpr[1] = local_paca->kvm_hstate.scratch1;
	vcpu->arch.regs.gpr[3] = local_paca->kvm_hstate.scratch2;

	/*
	 * After reading machine check regs (DAR, DSISR, SRR0/1) and hstate
	 * scratch (which we need to move into exsave to make re-entrant vs
	 * SRESET/MCE), register state is protected from reentrancy. However
	 * timebase, MMU, among other state is still set to guest, so don't
	 * enable MSR[RI] here. It gets enabled at the end, after in_guest
	 * is cleared.
	 *
	 * It is possible an NMI could come in here, which is why it is
	 * important to save the above state early so it can be debugged.
	 */

	vcpu->arch.regs.gpr[9] = exsave[EX_R9/sizeof(u64)];
	vcpu->arch.regs.gpr[10] = exsave[EX_R10/sizeof(u64)];
	vcpu->arch.regs.gpr[11] = exsave[EX_R11/sizeof(u64)];
	vcpu->arch.regs.gpr[12] = exsave[EX_R12/sizeof(u64)];
	vcpu->arch.regs.gpr[13] = exsave[EX_R13/sizeof(u64)];
	vcpu->arch.ppr = exsave[EX_PPR/sizeof(u64)];
	vcpu->arch.cfar = exsave[EX_CFAR/sizeof(u64)];
	vcpu->arch.regs.ctr = exsave[EX_CTR/sizeof(u64)];

	vcpu->arch.last_inst = KVM_INST_FETCH_FAILED;

	if (unlikely(trap == BOOK3S_INTERRUPT_MACHINE_CHECK)) {
		vcpu->arch.fault_dar = exsave[EX_DAR/sizeof(u64)];
		vcpu->arch.fault_dsisr = exsave[EX_DSISR/sizeof(u64)];
		kvmppc_realmode_machine_check(vcpu);

	} else if (unlikely(trap == BOOK3S_INTERRUPT_HMI)) {
		kvmppc_p9_realmode_hmi_handler(vcpu);

	} else if (trap == BOOK3S_INTERRUPT_H_EMUL_ASSIST) {
		vcpu->arch.emul_inst = mfspr(SPRN_HEIR);

	} else if (trap == BOOK3S_INTERRUPT_H_DATA_STORAGE) {
		vcpu->arch.fault_dar = exsave[EX_DAR/sizeof(u64)];
		vcpu->arch.fault_dsisr = exsave[EX_DSISR/sizeof(u64)];
		vcpu->arch.fault_gpa = mfspr(SPRN_ASDR);

	} else if (trap == BOOK3S_INTERRUPT_H_INST_STORAGE) {
		vcpu->arch.fault_gpa = mfspr(SPRN_ASDR);

	} else if (trap == BOOK3S_INTERRUPT_H_FAC_UNAVAIL) {
		vcpu->arch.hfscr = mfspr(SPRN_HFSCR);

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
	/*
	 * Softpatch interrupt for transactional memory emulation cases
	 * on POWER9 DD2.2.  This is early in the guest exit path - we
	 * haven't saved registers or done a treclaim yet.
	 */
	} else if (trap == BOOK3S_INTERRUPT_HV_SOFTPATCH) {
		vcpu->arch.emul_inst = mfspr(SPRN_HEIR);

		/*
		 * The cases we want to handle here are those where the guest
		 * is in real suspend mode and is trying to transition to
		 * transactional mode.
		 */
		if (!local_paca->kvm_hstate.fake_suspend &&
				(vcpu->arch.shregs.msr & MSR_TS_S)) {
			if (kvmhv_p9_tm_emulation_early(vcpu)) {
				/*
				 * Go straight back into the guest with the
				 * new NIP/MSR as set by TM emulation.
				 */
				mtspr(SPRN_HSRR0, vcpu->arch.regs.nip);
				mtspr(SPRN_HSRR1, vcpu->arch.shregs.msr);
				goto tm_return_to_guest;
			}
		}
#endif
	}

	/* Advance host PURR/SPURR by the amount used by guest */
	purr = mfspr(SPRN_PURR);
	spurr = mfspr(SPRN_SPURR);
	local_paca->kvm_hstate.host_purr += purr - vcpu->arch.purr;
	local_paca->kvm_hstate.host_spurr += spurr - vcpu->arch.spurr;
	vcpu->arch.purr = purr;
	vcpu->arch.spurr = spurr;

	vcpu->arch.ic = mfspr(SPRN_IC);
	vcpu->arch.pid = mfspr(SPRN_PID);
	vcpu->arch.psscr = mfspr(SPRN_PSSCR_PR);

	vcpu->arch.shregs.sprg0 = mfspr(SPRN_SPRG0);
	vcpu->arch.shregs.sprg1 = mfspr(SPRN_SPRG1);
	vcpu->arch.shregs.sprg2 = mfspr(SPRN_SPRG2);
	vcpu->arch.shregs.sprg3 = mfspr(SPRN_SPRG3);

	dpdes = mfspr(SPRN_DPDES);
	if (dpdes)
		vcpu->arch.doorbell_request = 1;

	vc->vtb = mfspr(SPRN_VTB);

	dec = mfspr(SPRN_DEC);
	if (!(lpcr & LPCR_LD)) /* Sign extend if not using large decrementer */
		dec = (s32) dec;
	*tb = mftb();
	vcpu->arch.dec_expires = dec + *tb;

	if (vc->tb_offset_applied) {
		u64 new_tb = *tb - vc->tb_offset_applied;
		mtspr(SPRN_TBU40, new_tb);
		if ((mftb() & 0xffffff) < (new_tb & 0xffffff)) {
			new_tb += 0x1000000;
			mtspr(SPRN_TBU40, new_tb);
		}
		*tb = new_tb;
		vc->tb_offset_applied = 0;
	}

	save_clear_guest_mmu(kvm, vcpu);
	switch_mmu_to_host(kvm, host_pidr);

	/*
	 * Enable MSR here in order to have facilities enabled to save
	 * guest registers. This enables MMU (if we were in realmode), so
	 * only switch MMU on after the MMU is switched to host, to avoid
	 * the P9_RADIX_PREFETCH_BUG or hash guest context.
	 */
	if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) &&
			vcpu->arch.shregs.msr & MSR_TS_MASK)
		msr |= MSR_TS_S;
	__mtmsrd(msr, 0);

	store_vcpu_state(vcpu);

	mtspr(SPRN_PURR, local_paca->kvm_hstate.host_purr);
	mtspr(SPRN_SPURR, local_paca->kvm_hstate.host_spurr);

	if (cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) {
		/* Preserve PSSCR[FAKE_SUSPEND] until we've called kvmppc_save_tm_hv */
		mtspr(SPRN_PSSCR, host_hpsscr |
		      (local_paca->kvm_hstate.fake_suspend << PSSCR_FAKE_SUSPEND_LG));
	}

	mtspr(SPRN_HFSCR, host_hfscr);
	if (vcpu->arch.ciabr != host_ciabr)
		mtspr(SPRN_CIABR, host_ciabr);

	if (dawr_enabled()) {
		if (vcpu->arch.dawr0 != host_dawr0)
			mtspr(SPRN_DAWR0, host_dawr0);
		if (vcpu->arch.dawrx0 != host_dawrx0)
			mtspr(SPRN_DAWRX0, host_dawrx0);
		if (cpu_has_feature(CPU_FTR_DAWR1)) {
			if (vcpu->arch.dawr1 != host_dawr1)
				mtspr(SPRN_DAWR1, host_dawr1);
			if (vcpu->arch.dawrx1 != host_dawrx1)
				mtspr(SPRN_DAWRX1, host_dawrx1);
		}
	}

	if (dpdes)
		mtspr(SPRN_DPDES, 0);
	if (vc->pcr)
		mtspr(SPRN_PCR, PCR_MASK);

	/* HDEC must be at least as large as DEC, so decrementer_max fits */
	mtspr(SPRN_HDEC, decrementer_max);

	timer_rearm_host_dec(*tb);

	restore_p9_host_os_sprs(vcpu, &host_os_sprs);

	barrier(); /* Close in_guest critical section */
	WRITE_ONCE(local_paca->kvm_hstate.in_guest, KVM_GUEST_MODE_NONE);
	/* Interrupts are recoverable at this point */

	/*
	 * cp_abort is required if the processor supports local copy-paste
	 * to clear the copy buffer that was under control of the guest.
	 */
	if (cpu_has_feature(CPU_FTR_ARCH_31))
		asm volatile(PPC_CP_ABORT);

out:
	return trap;
}
EXPORT_SYMBOL_GPL(kvmhv_vcpu_entry_p9);