xen: HVM X2APIC support

This patch is similiar to Gleb Natapov's patch for KVM, which enable the
hypervisor to emulate x2apic feature for the guest. By this way, the emulation
of lapic would be simpler with x2apic interface(MSR), and faster.

[v2: Re-organized 'xen_hvm_need_lapic' per Ian Campbell suggestion]

Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 12 insertions, 19 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 44dcad43989d..5b8986fe3371 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1256,25 +1256,6 @@ asmlinkage void __init xen_start_kernel(void)
 #endif
 }
 
-static uint32_t xen_cpuid_base(void)
-{
-        uint32_t base, eax, ebx, ecx, edx;
-        char signature[13];
-
-        for (base = 0x40000000; base < 0x40010000; base += 0x100) {
-                cpuid(base, &eax, &ebx, &ecx, &edx);
-                *(uint32_t *)(signature + 0) = ebx;
-                *(uint32_t *)(signature + 4) = ecx;
-                *(uint32_t *)(signature + 8) = edx;
-                signature[12] = 0;
-
-                if (!strcmp("XenVMMXenVMM", signature) && ((eax - base) >= 2))
-                        return base;
-        }
-
-        return 0;
-}
-
 static int init_hvm_pv_info(int *major, int *minor)
 {
         uint32_t eax, ebx, ecx, edx, pages, msr, base;
@@ -1384,6 +1365,18 @@ static bool __init xen_hvm_platform(void)
         return true;
 }
 
+bool xen_hvm_need_lapic(void)
+{
+        if (xen_pv_domain())
+                return false;
+        if (!xen_hvm_domain())
+                return false;
+        if (xen_feature(XENFEAT_hvm_pirqs) && xen_have_vector_callback)
+                return false;
+        return true;
+}
+EXPORT_SYMBOL_GPL(xen_hvm_need_lapic);
+
 const __refconst struct hypervisor_x86 x86_hyper_xen_hvm = {
         .name                   = "Xen HVM",
         .detect                 = xen_hvm_platform,