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@xxxxxxx>
---
v1 -> v2:
- kvm guest patch framework: introduce patch_ins
v2 -> v3:
- add self-test in guest code
- remove superfluous new lines in generic guest code
---
arch/powerpc/kernel/kvm.c | 95 +++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 95 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
index a5ece71..e93366f 100644
--- a/arch/powerpc/kernel/kvm.c
+++ b/arch/powerpc/kernel/kvm.c
@@ -33,6 +33,62 @@
#define KVM_MAGIC_PAGE (-4096L)
#define magic_var(x) KVM_MAGIC_PAGE + offsetof(struct kvm_vcpu_arch_shared, x)
+#define KVM_MASK_RT 0x03e00000
+
+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;
+ u32 tmp;
+
+ /* Tell the host to map the magic page to -4096 on all CPUs */
+ on_each_cpu(kvm_map_magic_page, NULL, 1);
+
+ /* Quick self-test to see if the mapping works */
+ if (__get_user(tmp, (u32*)KVM_MAGIC_PAGE)) {
+ kvm_patching_worked = false;
+ return;
+ }
+
+ /* Now loop through all code and find instructions */
+ start = (void*)_stext;
+ end = (void*)_etext;
+
+ for (p = start; p < end; p++)
+ kvm_check_ins(p);
+
+ printk(KERN_INFO "KVM: Live patching for a fast VM %s\n",
+ kvm_patching_worked ? "worked" : "failed");
+}
+
unsigned long kvm_hypercall(unsigned long *in,
unsigned long *out,
unsigned long nr)
@@ -69,3 +125,42 @@ unsigned long kvm_hypercall(unsigned long *in,
return r3;
}
EXPORT_SYMBOL_GPL(kvm_hypercall);
+
+static int kvm_para_setup(void)
+{
+ extern u32 kvm_hypercall_start;
+ struct device_node *hyper_node;
+ u32 *insts;
+ int len, i;
+
+ hyper_node = of_find_node_by_path("/hypervisor");
+ if (!hyper_node)
+ return -1;
+
+ insts = (u32*)of_get_property(hyper_node, "hcall-instructions", &len);
+ if (len % 4)
+ return -1;
+ if (len > (4 * 4))
+ return -1;
+
+ for (i = 0; i < (len / 4); i++)
+ kvm_patch_ins(&(&kvm_hypercall_start)[i], insts[i]);
+
+ return 0;
+}
+
+static int __init kvm_guest_init(void)
+{
+ if (!kvm_para_available())
+ return 0;
+
+ if (kvm_para_setup())
+ return 0;
+
+ if (kvm_para_has_feature(KVM_FEATURE_MAGIC_PAGE))
+ kvm_use_magic_page();
+
+ return 0;
+}
+
+postcore_initcall(kvm_guest_init);
--
1.6.0.2
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