x86: Correctly detect hypervisor

We try to handle the hypervisor compatibility mode by detecting hypervisor
through a specific order. This is not robust, since hypervisors may implement
each others features.

This patch tries to handle this situation by always choosing the last one in the
CPUID leaves. This is done by letting .detect() return a priority instead of
true/false and just re-using the CPUID leaf where the signature were found as
the priority (or 1 if it was found by DMI). Then we can just pick hypervisor who
has the highest priority. Other sophisticated detection method could also be
implemented on top.

Suggested by H. Peter Anvin and Paolo Bonzini.

Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Doug Covelli <dcovelli@vmware.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dan Hecht <dhecht@vmware.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: http://lkml.kernel.org/r/1374742475-2485-4-git-send-email-jasowang@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/include/asm/hypervisor.h b/arch/x86/include/asm/hypervisor.h
index 2d4b5e6107cd70d2977a12c090b01ed7908a58ae..e42f758a0fbd9b14b38feaae9fbb3f1a2bfcd204 100644 (file)
--- a/arch/x86/include/asm/hypervisor.h
+++ b/arch/x86/include/asm/hypervisor.h
@@ -33,7 +33,7 @@ struct hypervisor_x86 {
        const char      *name;
 
        /* Detection routine */
-       bool            (*detect)(void);
+       uint32_t        (*detect)(void);
 
        /* Adjust CPU feature bits (run once per CPU) */
        void            (*set_cpu_features)(struct cpuinfo_x86 *);

diff --git a/arch/x86/kernel/cpu/hypervisor.c b/arch/x86/kernel/cpu/hypervisor.c
index 87279212d318664dd51ddc0d6c6dc6a3c458c848..36ce402a3fa5b311014b30e3dd8cac69d5f68a88 100644 (file)
--- a/arch/x86/kernel/cpu/hypervisor.c
+++ b/arch/x86/kernel/cpu/hypervisor.c
@@ -25,11 +25,6 @@
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
 
-/*
- * Hypervisor detect order.  This is specified explicitly here because
- * some hypervisors might implement compatibility modes for other
- * hypervisors and therefore need to be detected in specific sequence.
- */
 static const __initconst struct hypervisor_x86 * const hypervisors[] =
 {
 #ifdef CONFIG_XEN_PVHVM
@@ -49,15 +44,19 @@ static inline void __init
 detect_hypervisor_vendor(void)
 {
        const struct hypervisor_x86 *h, * const *p;
+       uint32_t pri, max_pri = 0;
 
        for (p = hypervisors; p < hypervisors + ARRAY_SIZE(hypervisors); p++) {
                h = *p;
-               if (h->detect()) {
+               pri = h->detect();
+               if (pri != 0 && pri > max_pri) {
+                       max_pri = pri;
                        x86_hyper = h;
-                       printk(KERN_INFO "Hypervisor detected: %s\n", h->name);
-                       break;
                }
        }
+
+       if (max_pri)
+               printk(KERN_INFO "Hypervisor detected: %s\n", x86_hyper->name);
 }
 
 void init_hypervisor(struct cpuinfo_x86 *c)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 8f4be53ea04b84f4eaa7a78a4bcd6e6e625c9afc..71a39f3621baa39f25f567029ef41e9e8374e612 100644 (file)
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -27,20 +27,23 @@
 struct ms_hyperv_info ms_hyperv;
 EXPORT_SYMBOL_GPL(ms_hyperv);
 
-static bool __init ms_hyperv_platform(void)
+static uint32_t  __init ms_hyperv_platform(void)
 {
        u32 eax;
        u32 hyp_signature[3];
 
        if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
-               return false;
+               return 0;
 
        cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
              &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
 
-       return eax >= HYPERV_CPUID_MIN &&
-               eax <= HYPERV_CPUID_MAX &&
-               !memcmp("Microsoft Hv", hyp_signature, 12);
+       if (eax >= HYPERV_CPUID_MIN &&
+           eax <= HYPERV_CPUID_MAX &&
+           !memcmp("Microsoft Hv", hyp_signature, 12))
+               return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
+
+       return 0;
 }
 
 static cycle_t read_hv_clock(struct clocksource *arg)

diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 7076878404ec0c450daa78a743eef9190db3d592..628a059a9a0663ef7cbdf07e4750c9e1e4f53006 100644 (file)
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -93,7 +93,7 @@ static void __init vmware_platform_setup(void)
  * serial key should be enough, as this will always have a VMware
  * specific string when running under VMware hypervisor.
  */
-static bool __init vmware_platform(void)
+static uint32_t __init vmware_platform(void)
 {
        if (cpu_has_hypervisor) {
                unsigned int eax;
@@ -102,12 +102,12 @@ static bool __init vmware_platform(void)
                cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &hyper_vendor_id[0],
                      &hyper_vendor_id[1], &hyper_vendor_id[2]);
                if (!memcmp(hyper_vendor_id, "VMwareVMware", 12))
-                       return true;
+                       return CPUID_VMWARE_INFO_LEAF;
        } else if (dmi_available && dmi_name_in_serial("VMware") &&
                   __vmware_platform())
-               return true;
+               return 1;
 
-       return false;
+       return 0;
 }
 
 /*

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index a96d32cc55b8456e8567cd66f8848b62a449150b..7817afdac301ca55d6bf26f99d513aae607242e1 100644 (file)
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -498,11 +498,9 @@ void __init kvm_guest_init(void)
 #endif
 }
 
-static bool __init kvm_detect(void)
+static uint32_t __init kvm_detect(void)
 {
-       if (!kvm_para_available())
-               return false;
-       return true;
+       return kvm_cpuid_base();
 }
 
 const struct hypervisor_x86 x86_hyper_kvm __refconst = {

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 193097ef3d7d0d886ffa88b6c735571b9f66c1ec..2fcaedc0b739d06a399db042895d8592526b6934 100644 (file)
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1720,15 +1720,12 @@ static void __init xen_hvm_guest_init(void)
        xen_hvm_init_mmu_ops();
 }
 
-static bool __init xen_hvm_platform(void)
+static uint32_t __init xen_hvm_platform(void)
 {
        if (xen_pv_domain())
-               return false;
-
-       if (!xen_cpuid_base())
-               return false;
+               return 0;
 
-       return true;
+       return xen_cpuid_base();
 }
 
 bool xen_hvm_need_lapic(void)