From 9df56f19a500bea90d160be1bf77e4fbcd204d3f Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Thu, 25 Jul 2013 16:54:35 +0800 Subject: 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 Cc: Haiyang Zhang Cc: Konrad Rzeszutek Wilk Cc: Jeremy Fitzhardinge Cc: Doug Covelli Cc: Borislav Petkov Cc: Dan Hecht Cc: Paul Gortmaker Cc: Marcelo Tosatti Cc: Gleb Natapov Cc: Paolo Bonzini Cc: Frederic Weisbecker Signed-off-by: Jason Wang Link: http://lkml.kernel.org/r/1374742475-2485-4-git-send-email-jasowang@redhat.com Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/mshyperv.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'arch/x86/kernel/cpu/mshyperv.c') diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 8f4be53ea04b..71a39f3621ba 100644 --- 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) -- cgit v1.2.3