> -----Original Message-----
> From: Paolo Bonzini [mailto:paolo.bonz...@gmail.com] On Behalf Of Paolo
> Bonzini
> Sent: Friday, October 2, 2015 2:27 AM
> To: linux-kernel@vger.kernel.org
> Cc: KY Srinivasan <k...@microsoft.com>; Haiyang Zhang
> <haiya...@microsoft.com>; x...@kernel.org; de...@linuxdriverproject.org;
> alex.william...@redhat.com
> Subject: [PATCH] x86: guest: rely on leaf 0x40000001 to detect Hyper-V
>
> The specification says that "Microsoft Hv" is actually a vendor ID field
> that is only used for reporting and diagnostic purposes. The actual
> field that you need to check is the interface ID that you get in eax
> when querying the HYPERV_CPUID_INTERFACE.
>
> Change ms_hyperv_platform to actually do what the specification suggests.
> This roughy matches what Windows looks for, though Windows actually
> ignores HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS completely.
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
Thanks Paolo.
Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
> ---
> arch/x86/kernel/cpu/mshyperv.c | 14 ++++++--------
> 1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/mshyperv.c
> b/arch/x86/kernel/cpu/mshyperv.c
> index 381c8b9b3a33..7910e7fd705b 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -116,18 +116,16 @@ static void hv_machine_crash_shutdown(struct
> pt_regs *regs)
> static uint32_t __init ms_hyperv_platform(void)
> {
> u32 eax;
> - u32 hyp_signature[3];
>
> if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
> return 0;
>
> - cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
> - &eax, &hyp_signature[0], &hyp_signature[1],
> &hyp_signature[2]);
> -
> - if (eax >= HYPERV_CPUID_MIN &&
> - eax <= HYPERV_CPUID_MAX &&
> - !memcmp("Microsoft Hv", hyp_signature, 12))
> - return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
> + eax =
> cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS);
> + if (eax >= HYPERV_CPUID_MIN && eax <= HYPERV_CPUID_MAX) {
> + eax = cpuid_eax(HYPERV_CPUID_INTERFACE);
> + if (!memcmp(&eax, "Hv#1", sizeof(eax)))
> + return
> HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
> + }
>
> return 0;
> }
> --
> 2.5.0
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