KVM: PPC: Add support for Book3S processors in hypervisor mode

This adds support for KVM running on 64-bit Book 3S processors,
specifically POWER7, in hypervisor mode.  Using hypervisor mode means
that the guest can use the processor's supervisor mode.  That means
that the guest can execute privileged instructions and access privileged
registers itself without trapping to the host.  This gives excellent
performance, but does mean that KVM cannot emulate a processor
architecture other than the one that the hardware implements.

This code assumes that the guest is running paravirtualized using the
PAPR (Power Architecture Platform Requirements) interface, which is the
interface that IBM's PowerVM hypervisor uses.  That means that existing
Linux distributions that run on IBM pSeries machines will also run
under KVM without modification.  In order to communicate the PAPR
hypercalls to qemu, this adds a new KVM_EXIT_PAPR_HCALL exit code
to include/linux/kvm.h.

Currently the choice between book3s_hv support and book3s_pr support
(i.e. the existing code, which runs the guest in user mode) has to be
made at kernel configuration time, so a given kernel binary can only
do one or the other.

This new book3s_hv code doesn't support MMIO emulation at present.
Since we are running paravirtualized guests, this isn't a serious
restriction.

With the guest running in supervisor mode, most exceptions go straight
to the guest.  We will never get data or instruction storage or segment
interrupts, alignment interrupts, decrementer interrupts, program
interrupts, single-step interrupts, etc., coming to the hypervisor from
the guest.  Therefore this introduces a new KVMTEST_NONHV macro for the
exception entry path so that we don't have to do the KVM test on entry
to those exception handlers.

We do however get hypervisor decrementer, hypervisor data storage,
hypervisor instruction storage, and hypervisor emulation assist
interrupts, so we have to handle those.

In hypervisor mode, real-mode accesses can access all of RAM, not just
a limited amount.  Therefore we put all the guest state in the vcpu.arch
and use the shadow_vcpu in the PACA only for temporary scratch space.
We allocate the vcpu with kzalloc rather than vzalloc, and we don't use
anything in the kvmppc_vcpu_book3s struct, so we don't allocate it.
We don't have a shared page with the guest, but we still need a
kvm_vcpu_arch_shared struct to store the values of various registers,
so we include one in the vcpu_arch struct.

The POWER7 processor has a restriction that all threads in a core have
to be in the same partition.  MMU-on kernel code counts as a partition
(partition 0), so we have to do a partition switch on every entry to and
exit from the guest.  At present we require the host and guest to run
in single-thread mode because of this hardware restriction.

This code allocates a hashed page table for the guest and initializes
it with HPTEs for the guest's Virtual Real Memory Area (VRMA).  We
require that the guest memory is allocated using 16MB huge pages, in
order to simplify the low-level memory management.  This also means that
we can get away without tracking paging activity in the host for now,
since huge pages can't be paged or swapped.

This also adds a few new exports needed by the book3s_hv code.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 445 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
new file mode 100644
index 000000000000..60b7300568c8
--- /dev/null
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -0,0 +1,445 @@
+/*
+ * Copyright 2011 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
+ * Copyright (C) 2009. SUSE Linux Products GmbH. All rights reserved.
+ *
+ * Authors:
+ *    Paul Mackerras <paulus@au1.ibm.com>
+ *    Alexander Graf <agraf@suse.de>
+ *    Kevin Wolf <mail@kevin-wolf.de>
+ *
+ * Description: KVM functions specific to running on Book 3S
+ * processors in hypervisor mode (specifically POWER7 and later).
+ *
+ * This file is derived from arch/powerpc/kvm/book3s.c,
+ * by Alexander Graf <agraf@suse.de>.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kvm_host.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/preempt.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/anon_inodes.h>
+#include <linux/cpumask.h>
+
+#include <asm/reg.h>
+#include <asm/cputable.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+#include <asm/uaccess.h>
+#include <asm/io.h>
+#include <asm/kvm_ppc.h>
+#include <asm/kvm_book3s.h>
+#include <asm/mmu_context.h>
+#include <asm/lppaca.h>
+#include <asm/processor.h>
+#include <linux/gfp.h>
+#include <linux/sched.h>
+#include <linux/vmalloc.h>
+#include <linux/highmem.h>
+
+/* #define EXIT_DEBUG */
+/* #define EXIT_DEBUG_SIMPLE */
+/* #define EXIT_DEBUG_INT */
+
+void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+{
+	local_paca->kvm_hstate.kvm_vcpu = vcpu;
+}
+
+void kvmppc_core_vcpu_put(struct kvm_vcpu *vcpu)
+{
+}
+
+void kvmppc_vcpu_block(struct kvm_vcpu *vcpu)
+{
+	u64 now;
+	unsigned long dec_nsec;
+
+	now = get_tb();
+	if (now >= vcpu->arch.dec_expires && !kvmppc_core_pending_dec(vcpu))
+		kvmppc_core_queue_dec(vcpu);
+	if (vcpu->arch.pending_exceptions)
+		return;
+	if (vcpu->arch.dec_expires != ~(u64)0) {
+		dec_nsec = (vcpu->arch.dec_expires - now) * NSEC_PER_SEC /
+			tb_ticks_per_sec;
+		hrtimer_start(&vcpu->arch.dec_timer, ktime_set(0, dec_nsec),
+			      HRTIMER_MODE_REL);
+	}
+
+	kvm_vcpu_block(vcpu);
+	vcpu->stat.halt_wakeup++;
+
+	if (vcpu->arch.dec_expires != ~(u64)0)
+		hrtimer_try_to_cancel(&vcpu->arch.dec_timer);
+}
+
+void kvmppc_set_msr(struct kvm_vcpu *vcpu, u64 msr)
+{
+	vcpu->arch.shregs.msr = msr;
+}
+
+void kvmppc_set_pvr(struct kvm_vcpu *vcpu, u32 pvr)
+{
+	vcpu->arch.pvr = pvr;
+}
+
+void kvmppc_dump_regs(struct kvm_vcpu *vcpu)
+{
+	int r;
+
+	pr_err("vcpu %p (%d):\n", vcpu, vcpu->vcpu_id);
+	pr_err("pc  = %.16lx  msr = %.16llx  trap = %x\n",
+	       vcpu->arch.pc, vcpu->arch.shregs.msr, vcpu->arch.trap);
+	for (r = 0; r < 16; ++r)
+		pr_err("r%2d = %.16lx  r%d = %.16lx\n",
+		       r, kvmppc_get_gpr(vcpu, r),
+		       r+16, kvmppc_get_gpr(vcpu, r+16));
+	pr_err("ctr = %.16lx  lr  = %.16lx\n",
+	       vcpu->arch.ctr, vcpu->arch.lr);
+	pr_err("srr0 = %.16llx srr1 = %.16llx\n",
+	       vcpu->arch.shregs.srr0, vcpu->arch.shregs.srr1);
+	pr_err("sprg0 = %.16llx sprg1 = %.16llx\n",
+	       vcpu->arch.shregs.sprg0, vcpu->arch.shregs.sprg1);
+	pr_err("sprg2 = %.16llx sprg3 = %.16llx\n",
+	       vcpu->arch.shregs.sprg2, vcpu->arch.shregs.sprg3);
+	pr_err("cr = %.8x  xer = %.16lx  dsisr = %.8x\n",
+	       vcpu->arch.cr, vcpu->arch.xer, vcpu->arch.shregs.dsisr);
+	pr_err("dar = %.16llx\n", vcpu->arch.shregs.dar);
+	pr_err("fault dar = %.16lx dsisr = %.8x\n",
+	       vcpu->arch.fault_dar, vcpu->arch.fault_dsisr);
+	pr_err("SLB (%d entries):\n", vcpu->arch.slb_max);
+	for (r = 0; r < vcpu->arch.slb_max; ++r)
+		pr_err("  ESID = %.16llx VSID = %.16llx\n",
+		       vcpu->arch.slb[r].orige, vcpu->arch.slb[r].origv);
+	pr_err("lpcr = %.16lx sdr1 = %.16lx last_inst = %.8x\n",
+	       vcpu->arch.lpcr, vcpu->kvm->arch.sdr1,
+	       vcpu->arch.last_inst);
+}
+
+static int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
+			      struct task_struct *tsk)
+{
+	int r = RESUME_HOST;
+
+	vcpu->stat.sum_exits++;
+
+	run->exit_reason = KVM_EXIT_UNKNOWN;
+	run->ready_for_interrupt_injection = 1;
+	switch (vcpu->arch.trap) {
+	/* We're good on these - the host merely wanted to get our attention */
+	case BOOK3S_INTERRUPT_HV_DECREMENTER:
+		vcpu->stat.dec_exits++;
+		r = RESUME_GUEST;
+		break;
+	case BOOK3S_INTERRUPT_EXTERNAL:
+		vcpu->stat.ext_intr_exits++;
+		r = RESUME_GUEST;
+		break;
+	case BOOK3S_INTERRUPT_PERFMON:
+		r = RESUME_GUEST;
+		break;
+	case BOOK3S_INTERRUPT_PROGRAM:
+	{
+		ulong flags;
+		/*
+		 * Normally program interrupts are delivered directly
+		 * to the guest by the hardware, but we can get here
+		 * as a result of a hypervisor emulation interrupt
+		 * (e40) getting turned into a 700 by BML RTAS.
+		 */
+		flags = vcpu->arch.shregs.msr & 0x1f0000ull;
+		kvmppc_core_queue_program(vcpu, flags);
+		r = RESUME_GUEST;
+		break;
+	}
+	case BOOK3S_INTERRUPT_SYSCALL:
+	{
+		/* hcall - punt to userspace */
+		int i;
+
+		if (vcpu->arch.shregs.msr & MSR_PR) {
+			/* sc 1 from userspace - reflect to guest syscall */
+			kvmppc_book3s_queue_irqprio(vcpu, BOOK3S_INTERRUPT_SYSCALL);
+			r = RESUME_GUEST;
+			break;
+		}
+		run->papr_hcall.nr = kvmppc_get_gpr(vcpu, 3);
+		for (i = 0; i < 9; ++i)
+			run->papr_hcall.args[i] = kvmppc_get_gpr(vcpu, 4 + i);
+		run->exit_reason = KVM_EXIT_PAPR_HCALL;
+		vcpu->arch.hcall_needed = 1;
+		r = RESUME_HOST;
+		break;
+	}
+	/*
+	 * We get these next two if the guest does a bad real-mode access,
+	 * as we have enabled VRMA (virtualized real mode area) mode in the
+	 * LPCR.  We just generate an appropriate DSI/ISI to the guest.
+	 */
+	case BOOK3S_INTERRUPT_H_DATA_STORAGE:
+		vcpu->arch.shregs.dsisr = vcpu->arch.fault_dsisr;
+		vcpu->arch.shregs.dar = vcpu->arch.fault_dar;
+		kvmppc_inject_interrupt(vcpu, BOOK3S_INTERRUPT_DATA_STORAGE, 0);
+		r = RESUME_GUEST;
+		break;
+	case BOOK3S_INTERRUPT_H_INST_STORAGE:
+		kvmppc_inject_interrupt(vcpu, BOOK3S_INTERRUPT_INST_STORAGE,
+					0x08000000);
+		r = RESUME_GUEST;
+		break;
+	/*
+	 * This occurs if the guest executes an illegal instruction.
+	 * We just generate a program interrupt to the guest, since
+	 * we don't emulate any guest instructions at this stage.
+	 */
+	case BOOK3S_INTERRUPT_H_EMUL_ASSIST:
+		kvmppc_core_queue_program(vcpu, 0x80000);
+		r = RESUME_GUEST;
+		break;
+	default:
+		kvmppc_dump_regs(vcpu);
+		printk(KERN_EMERG "trap=0x%x | pc=0x%lx | msr=0x%llx\n",
+			vcpu->arch.trap, kvmppc_get_pc(vcpu),
+			vcpu->arch.shregs.msr);
+		r = RESUME_HOST;
+		BUG();
+		break;
+	}
+
+
+	if (!(r & RESUME_HOST)) {
+		/* To avoid clobbering exit_reason, only check for signals if
+		 * we aren't already exiting to userspace for some other
+		 * reason. */
+		if (signal_pending(tsk)) {
+			vcpu->stat.signal_exits++;
+			run->exit_reason = KVM_EXIT_INTR;
+			r = -EINTR;
+		} else {
+			kvmppc_core_deliver_interrupts(vcpu);
+		}
+	}
+
+	return r;
+}
+
+int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
+                                  struct kvm_sregs *sregs)
+{
+	int i;
+
+	sregs->pvr = vcpu->arch.pvr;
+
+	memset(sregs, 0, sizeof(struct kvm_sregs));
+	for (i = 0; i < vcpu->arch.slb_max; i++) {
+		sregs->u.s.ppc64.slb[i].slbe = vcpu->arch.slb[i].orige;
+		sregs->u.s.ppc64.slb[i].slbv = vcpu->arch.slb[i].origv;
+	}
+
+	return 0;
+}
+
+int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
+                                  struct kvm_sregs *sregs)
+{
+	int i, j;
+
+	kvmppc_set_pvr(vcpu, sregs->pvr);
+
+	j = 0;
+	for (i = 0; i < vcpu->arch.slb_nr; i++) {
+		if (sregs->u.s.ppc64.slb[i].slbe & SLB_ESID_V) {
+			vcpu->arch.slb[j].orige = sregs->u.s.ppc64.slb[i].slbe;
+			vcpu->arch.slb[j].origv = sregs->u.s.ppc64.slb[i].slbv;
+			++j;
+		}
+	}
+	vcpu->arch.slb_max = j;
+
+	return 0;
+}
+
+int kvmppc_core_check_processor_compat(void)
+{
+	if (cpu_has_feature(CPU_FTR_HVMODE_206))
+		return 0;
+	return -EIO;
+}
+
+struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
+{
+	struct kvm_vcpu *vcpu;
+	int err = -ENOMEM;
+	unsigned long lpcr;
+
+	vcpu = kzalloc(sizeof(struct kvm_vcpu), GFP_KERNEL);
+	if (!vcpu)
+		goto out;
+
+	err = kvm_vcpu_init(vcpu, kvm, id);
+	if (err)
+		goto free_vcpu;
+
+	vcpu->arch.shared = &vcpu->arch.shregs;
+	vcpu->arch.last_cpu = -1;
+	vcpu->arch.mmcr[0] = MMCR0_FC;
+	vcpu->arch.ctrl = CTRL_RUNLATCH;
+	/* default to host PVR, since we can't spoof it */
+	vcpu->arch.pvr = mfspr(SPRN_PVR);
+	kvmppc_set_pvr(vcpu, vcpu->arch.pvr);
+
+	lpcr = kvm->arch.host_lpcr & (LPCR_PECE | LPCR_LPES);
+	lpcr |= LPCR_VPM0 | LPCR_VRMA_L | (4UL << LPCR_DPFD_SH) | LPCR_HDICE;
+	vcpu->arch.lpcr = lpcr;
+
+	kvmppc_mmu_book3s_hv_init(vcpu);
+
+	return vcpu;
+
+free_vcpu:
+	kfree(vcpu);
+out:
+	return ERR_PTR(err);
+}
+
+void kvmppc_core_vcpu_free(struct kvm_vcpu *vcpu)
+{
+	kvm_vcpu_uninit(vcpu);
+	kfree(vcpu);
+}
+
+extern int __kvmppc_vcore_entry(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu);
+
+int kvmppc_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	u64 now;
+
+	if (signal_pending(current)) {
+		run->exit_reason = KVM_EXIT_INTR;
+		return -EINTR;
+	}
+
+	flush_fp_to_thread(current);
+	flush_altivec_to_thread(current);
+	flush_vsx_to_thread(current);
+	preempt_disable();
+
+	/*
+	 * Make sure we are running on thread 0, and that
+	 * secondary threads are offline.
+	 * XXX we should also block attempts to bring any
+	 * secondary threads online.
+	 */
+	if (threads_per_core > 1) {
+		int cpu = smp_processor_id();
+		int thr = cpu_thread_in_core(cpu);
+
+		if (thr)
+			goto out;
+		while (++thr < threads_per_core)
+			if (cpu_online(cpu + thr))
+				goto out;
+	}
+
+	kvm_guest_enter();
+
+	__kvmppc_vcore_entry(NULL, vcpu);
+
+	kvm_guest_exit();
+
+	preempt_enable();
+	kvm_resched(vcpu);
+
+	now = get_tb();
+	/* cancel pending dec exception if dec is positive */
+	if (now < vcpu->arch.dec_expires && kvmppc_core_pending_dec(vcpu))
+		kvmppc_core_dequeue_dec(vcpu);
+
+	return kvmppc_handle_exit(run, vcpu, current);
+
+ out:
+	preempt_enable();
+	return -EBUSY;
+}
+
+int kvmppc_core_prepare_memory_region(struct kvm *kvm,
+				struct kvm_userspace_memory_region *mem)
+{
+	if (mem->guest_phys_addr == 0 && mem->memory_size != 0)
+		return kvmppc_prepare_vrma(kvm, mem);
+	return 0;
+}
+
+void kvmppc_core_commit_memory_region(struct kvm *kvm,
+				struct kvm_userspace_memory_region *mem)
+{
+	if (mem->guest_phys_addr == 0 && mem->memory_size != 0)
+		kvmppc_map_vrma(kvm, mem);
+}
+
+int kvmppc_core_init_vm(struct kvm *kvm)
+{
+	long r;
+
+	/* Allocate hashed page table */
+	r = kvmppc_alloc_hpt(kvm);
+
+	return r;
+}
+
+void kvmppc_core_destroy_vm(struct kvm *kvm)
+{
+	kvmppc_free_hpt(kvm);
+}
+
+/* These are stubs for now */
+void kvmppc_mmu_pte_pflush(struct kvm_vcpu *vcpu, ulong pa_start, ulong pa_end)
+{
+}
+
+/* We don't need to emulate any privileged instructions or dcbz */
+int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
+                           unsigned int inst, int *advance)
+{
+	return EMULATE_FAIL;
+}
+
+int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs)
+{
+	return EMULATE_FAIL;
+}
+
+int kvmppc_core_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt)
+{
+	return EMULATE_FAIL;
+}
+
+static int kvmppc_book3s_hv_init(void)
+{
+	int r;
+
+	r = kvm_init(NULL, sizeof(struct kvm_vcpu), 0, THIS_MODULE);
+
+	if (r)
+		return r;
+
+	r = kvmppc_mmu_hv_init();
+
+	return r;
+}
+
+static void kvmppc_book3s_hv_exit(void)
+{
+	kvm_exit();
+}
+
+module_init(kvmppc_book3s_hv_init);
+module_exit(kvmppc_book3s_hv_exit);