KVM: ia64: Drop in SN2 replacement of fast path ITC emulation fault handler

Copy in SN2 RTC based ITC emulation for fast exit. The two versions
have the same size, so a dropin is simpler than patching the branch
instruction to hit the SN2 version.

Signed-off-by: Jes Sorensen <jes@sgi.com>
Acked-by: Xiantao Zhang <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 31 insertions, 1 deletions

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index ebbd995194fb..4623a90e515a 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1671,8 +1671,37 @@ out:
         return 0;
 }
 
+
+/*
+ * On SN2, the ITC isn't stable, so copy in fast path code to use the
+ * SN2 RTC, replacing the ITC based default verion.
+ */
+static void kvm_patch_vmm(struct kvm_vmm_info *vmm_info,
+                          struct module *module)
+{
+        unsigned long new_ar, new_ar_sn2;
+        unsigned long module_base;
+
+        if (!ia64_platform_is("sn2"))
+                return;
+
+        module_base = (unsigned long)module->module_core;
+
+        new_ar = kvm_vmm_base + vmm_info->patch_mov_ar - module_base;
+        new_ar_sn2 = kvm_vmm_base + vmm_info->patch_mov_ar_sn2 - module_base;
+
+        printk(KERN_INFO "kvm: Patching ITC emulation to use SGI SN2 RTC "
+               "as source\n");
+
+        /*
+         * Copy the SN2 version of mov_ar into place. They are both
+         * the same size, so 6 bundles is sufficient (6 * 0x10).
+         */
+        memcpy((void *)new_ar, (void *)new_ar_sn2, 0x60);
+}
+
 static int kvm_relocate_vmm(struct kvm_vmm_info *vmm_info,
-                                                struct module *module)
+                            struct module *module)
 {
         unsigned long module_base;
         unsigned long vmm_size;
@@ -1694,6 +1723,7 @@ static int kvm_relocate_vmm(struct kvm_vmm_info *vmm_info,
                 return -EFAULT;
 
         memcpy((void *)kvm_vmm_base, (void *)module_base, vmm_size);
+        kvm_patch_vmm(vmm_info, module);
         kvm_flush_icache(kvm_vmm_base, vmm_size);
 
         /*Recalculate kvm_vmm_info based on new VMM*/