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x86: Correctly detect hypervisor

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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>
This commit is contained in:
Jason Wang 2013-07-25 16:54:35 +08:00 • committed by H. Peter Anvin
parent 1085ba7f55
commit 9df56f19a5
6 changed files with 25 additions and 28 deletions
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13
arch/x86/kernel/cpu/mshyperv.c
View file

@ -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)