linux-kernel - RE: [PATCH] x86: guest: rely on leaf 0x40000001 to detect Hyper-V

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <BY2PR0301MB16544146559EB6AE7EA0F6E9A04B0@BY2PR0301MB1654.namprd03.prod.outlook.com>
Date:	Fri, 2 Oct 2015 14:37:11 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Paolo Bonzini <pbonzini@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	Haiyang Zhang <haiyangz@...rosoft.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"alex.williamson@...hat.com" <alex.williamson@...hat.com>
Subject: RE: [PATCH] x86: guest: rely on leaf 0x40000001 to detect Hyper-V



> -----Original Message-----
> From: Paolo Bonzini [mailto:paolo.bonzini@...il.com] On Behalf Of Paolo
> Bonzini
> Sent: Friday, October 2, 2015 2:27 AM
> To: linux-kernel@...r.kernel.org
> Cc: KY Srinivasan <kys@...rosoft.com>; Haiyang Zhang
> <haiyangz@...rosoft.com>; x86@...nel.org; devel@...uxdriverproject.org;
> alex.williamson@...hat.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 <pbonzini@...hat.com>

Thanks Paolo.

Signed-off-by: K. Y. Srinivasan <kys@...rosoft.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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/