KVM: PPC: Handle some PAPR hcalls in the kernel

This adds the infrastructure for handling PAPR hcalls in the kernel,
either early in the guest exit path while we are still in real mode,
or later once the MMU has been turned back on and we are in the full
kernel context.  The advantage of handling hcalls in real mode if
possible is that we avoid two partition switches -- and this will
become more important when we support SMT4 guests, since a partition
switch means we have to pull all of the threads in the core out of
the guest.  The disadvantage is that we can only access the kernel
linear mapping, not anything vmalloced or ioremapped, since the MMU
is off.

This also adds code to handle the following hcalls in real mode:

H_ENTER       Add an HPTE to the hashed page table
H_REMOVE      Remove an HPTE from the hashed page table
H_READ        Read HPTEs from the hashed page table
H_PROTECT     Change the protection bits in an HPTE
H_BULK_REMOVE Remove up to 4 HPTEs from the hashed page table
H_SET_DABR    Set the data address breakpoint register

Plus code to handle the following hcalls in the kernel:

H_CEDE        Idle the vcpu until an interrupt or H_PROD hcall arrives
H_PROD        Wake up a ceded vcpu
H_REGISTER_VPA Register a virtual processor area (VPA)

The code that runs in real mode has to be in the base kernel, not in
the module, if KVM is compiled as a module.  The real-mode code can
only access the kernel linear mapping, not vmalloc or ioremap space.

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

1 files changed, 169 insertions, 1 deletions

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 60b7300568c..af862c30b70 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -124,6 +124,158 @@ void kvmppc_dump_regs(struct kvm_vcpu *vcpu)
 	       vcpu->arch.last_inst);
 }
 
+struct kvm_vcpu *kvmppc_find_vcpu(struct kvm *kvm, int id)
+{
+	int r;
+	struct kvm_vcpu *v, *ret = NULL;
+
+	mutex_lock(&kvm->lock);
+	kvm_for_each_vcpu(r, v, kvm) {
+		if (v->vcpu_id == id) {
+			ret = v;
+			break;
+		}
+	}
+	mutex_unlock(&kvm->lock);
+	return ret;
+}
+
+static void init_vpa(struct kvm_vcpu *vcpu, struct lppaca *vpa)
+{
+	vpa->shared_proc = 1;
+	vpa->yield_count = 1;
+}
+
+static unsigned long do_h_register_vpa(struct kvm_vcpu *vcpu,
+				       unsigned long flags,
+				       unsigned long vcpuid, unsigned long vpa)
+{
+	struct kvm *kvm = vcpu->kvm;
+	unsigned long pg_index, ra, len;
+	unsigned long pg_offset;
+	void *va;
+	struct kvm_vcpu *tvcpu;
+
+	tvcpu = kvmppc_find_vcpu(kvm, vcpuid);
+	if (!tvcpu)
+		return H_PARAMETER;
+
+	flags >>= 63 - 18;
+	flags &= 7;
+	if (flags == 0 || flags == 4)
+		return H_PARAMETER;
+	if (flags < 4) {
+		if (vpa & 0x7f)
+			return H_PARAMETER;
+		/* registering new area; convert logical addr to real */
+		pg_index = vpa >> kvm->arch.ram_porder;
+		pg_offset = vpa & (kvm->arch.ram_psize - 1);
+		if (pg_index >= kvm->arch.ram_npages)
+			return H_PARAMETER;
+		if (kvm->arch.ram_pginfo[pg_index].pfn == 0)
+			return H_PARAMETER;
+		ra = kvm->arch.ram_pginfo[pg_index].pfn << PAGE_SHIFT;
+		ra |= pg_offset;
+		va = __va(ra);
+		if (flags <= 1)
+			len = *(unsigned short *)(va + 4);
+		else
+			len = *(unsigned int *)(va + 4);
+		if (pg_offset + len > kvm->arch.ram_psize)
+			return H_PARAMETER;
+		switch (flags) {
+		case 1:		/* register VPA */
+			if (len < 640)
+				return H_PARAMETER;
+			tvcpu->arch.vpa = va;
+			init_vpa(vcpu, va);
+			break;
+		case 2:		/* register DTL */
+			if (len < 48)
+				return H_PARAMETER;
+			if (!tvcpu->arch.vpa)
+				return H_RESOURCE;
+			len -= len % 48;
+			tvcpu->arch.dtl = va;
+			tvcpu->arch.dtl_end = va + len;
+			break;
+		case 3:		/* register SLB shadow buffer */
+			if (len < 8)
+				return H_PARAMETER;
+			if (!tvcpu->arch.vpa)
+				return H_RESOURCE;
+			tvcpu->arch.slb_shadow = va;
+			len = (len - 16) / 16;
+			tvcpu->arch.slb_shadow = va;
+			break;
+		}
+	} else {
+		switch (flags) {
+		case 5:		/* unregister VPA */
+			if (tvcpu->arch.slb_shadow || tvcpu->arch.dtl)
+				return H_RESOURCE;
+			tvcpu->arch.vpa = NULL;
+			break;
+		case 6:		/* unregister DTL */
+			tvcpu->arch.dtl = NULL;
+			break;
+		case 7:		/* unregister SLB shadow buffer */
+			tvcpu->arch.slb_shadow = NULL;
+			break;
+		}
+	}
+	return H_SUCCESS;
+}
+
+int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
+{
+	unsigned long req = kvmppc_get_gpr(vcpu, 3);
+	unsigned long target, ret = H_SUCCESS;
+	struct kvm_vcpu *tvcpu;
+
+	switch (req) {
+	case H_CEDE:
+		vcpu->arch.shregs.msr |= MSR_EE;
+		vcpu->arch.ceded = 1;
+		smp_mb();
+		if (!vcpu->arch.prodded)
+			kvmppc_vcpu_block(vcpu);
+		else
+			vcpu->arch.prodded = 0;
+		smp_mb();
+		vcpu->arch.ceded = 0;
+		break;
+	case H_PROD:
+		target = kvmppc_get_gpr(vcpu, 4);
+		tvcpu = kvmppc_find_vcpu(vcpu->kvm, target);
+		if (!tvcpu) {
+			ret = H_PARAMETER;
+			break;
+		}
+		tvcpu->arch.prodded = 1;
+		smp_mb();
+		if (vcpu->arch.ceded) {
+			if (waitqueue_active(&vcpu->wq)) {
+				wake_up_interruptible(&vcpu->wq);
+				vcpu->stat.halt_wakeup++;
+			}
+		}
+		break;
+	case H_CONFER:
+		break;
+	case H_REGISTER_VPA:
+		ret = do_h_register_vpa(vcpu, kvmppc_get_gpr(vcpu, 4),
+					kvmppc_get_gpr(vcpu, 5),
+					kvmppc_get_gpr(vcpu, 6));
+		break;
+	default:
+		return RESUME_HOST;
+	}
+	kvmppc_set_gpr(vcpu, 3, ret);
+	vcpu->arch.hcall_needed = 0;
+	return RESUME_GUEST;
+}
+
 static int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			      struct task_struct *tsk)
 {
@@ -318,7 +470,7 @@ void kvmppc_core_vcpu_free(struct kvm_vcpu *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)
+static int kvmppc_run_vcpu(struct kvm_run *run, struct kvm_vcpu *vcpu)
 {
 	u64 now;
 
@@ -370,6 +522,22 @@ int kvmppc_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	return -EBUSY;
 }
 
+int kvmppc_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	int r;
+
+	do {
+		r = kvmppc_run_vcpu(run, vcpu);
+
+		if (run->exit_reason == KVM_EXIT_PAPR_HCALL &&
+		    !(vcpu->arch.shregs.msr & MSR_PR)) {
+			r = kvmppc_pseries_do_hcall(vcpu);
+			kvmppc_core_deliver_interrupts(vcpu);
+		}
+	} while (r == RESUME_GUEST);
+	return r;
+}
+
 int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 				struct kvm_userspace_memory_region *mem)
 {