[PATCH 18/27] KVM: PPC: KVM PV guest stubs

[Alexander Graf <agraf@suse.de>]

We will soon start and replace instructions from the text section with
other, paravirtualized versions. To ease the readability of those patches
I split out the generic looping and magic page mapping code out.

This patch still only contains stubs. But at least it loops through the
text section :).

Signed-off-by: Alexander Graf <agraf@suse.de>

---

v1 -> v2:

  - kvm guest patch framework: introduce patch_ins
---
 arch/powerpc/kernel/kvm.c |   63 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 63 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
index 2d8dd73..1f328d5 100644
--- a/arch/powerpc/kernel/kvm.c
+++ b/arch/powerpc/kernel/kvm.c
@@ -32,3 +32,66 @@
 #define KVM_MAGIC_PAGE		(-4096L)
 #define magic_var(x) KVM_MAGIC_PAGE + offsetof(struct kvm_vcpu_arch_shared, x)
 
+static bool kvm_patching_worked = true;
+
+static inline void kvm_patch_ins(u32 *inst, u32 new_inst)
+{
+	*inst = new_inst;
+	flush_icache_range((ulong)inst, (ulong)inst + 4);
+}
+
+static void kvm_map_magic_page(void *data)
+{
+	kvm_hypercall2(KVM_HC_PPC_MAP_MAGIC_PAGE,
+		       KVM_MAGIC_PAGE,  /* Physical Address */
+		       KVM_MAGIC_PAGE); /* Effective Address */
+}
+
+static void kvm_check_ins(u32 *inst)
+{
+	u32 _inst = *inst;
+	u32 inst_no_rt = _inst & ~KVM_MASK_RT;
+	u32 inst_rt = _inst & KVM_MASK_RT;
+
+	switch (inst_no_rt) {
+	}
+
+	switch (_inst) {
+	}
+}
+
+static void kvm_use_magic_page(void)
+{
+	u32 *p;
+	u32 *start, *end;
+
+	/* Tell the host to map the magic page to -4096 on all CPUs */
+
+	on_each_cpu(kvm_map_magic_page, NULL, 1);
+
+	/* Now loop through all code and find instructions */
+
+	start = (void*)_stext;
+	end = (void*)_etext;
+
+	for (p = start; p < end; p++)
+		kvm_check_ins(p);
+}
+
+static int __init kvm_guest_init(void)
+{
+	char *p;
+
+	if (!kvm_para_available())
+		return 0;
+
+	if (kvm_para_has_feature(KVM_FEATURE_MAGIC_PAGE))
+		kvm_use_magic_page();
+
+	printk(KERN_INFO "KVM: Live patching for a fast VM %s\n",
+			 kvm_patching_worked ? "worked" : "failed");
+
+	return 0;
+}
+
+postcore_initcall(kvm_guest_init);
-- 
1.6.0.2