From: Juergen Gross <jgross@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org
Cc: boris.ostrovsky@oracle.com
Subject: Re: [Xen-devel] [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave
Date: Tue, 18 Apr 2017 13:56:54 +0200 [thread overview]
Message-ID: <ef620d84-4517-9c9a-e883-fb1a4655ff88@suse.com> (raw)
In-Reply-To: <2df54917-e8d1-403a-20ff-b956e568bce8@citrix.com>
On 18/04/17 12:02, Andrew Cooper wrote:
> On 18/04/17 07:31, Juergen Gross wrote:
>> @@ -281,22 +274,24 @@ static bool __init xen_check_mwait(void)
>> return false;
>> #endif
>> }
>> -static void __init xen_init_cpuid_mask(void)
>> +
>> +static bool __init xen_check_xsave(void)
>> {
>> - unsigned int ax, bx, cx, dx;
>> - unsigned int xsave_mask;
>> + unsigned int err, eax, edx;
>>
>> - ax = 1;
>> - cx = 0;
>> - cpuid(1, &ax, &bx, &cx, &dx);
>> + /* Test OSXSAVE capability via xgetbv instruction. */
>
> The code is fine, but this comment isn't going to be any help to people
> reading this code in 6 months time.
>
> How about this:
>
> "Xen 4.0 and older accidentally leaked the host XSAVE flag into guest
> view, despite not being able to support guests using the functionality.
> Probe for the actual availability of XSAVE by seeing whether xgetbv
> executes successfully or raises #UD."
I'll update the comment.
> Everything else is fine, so Reviewed-by: Andrew Cooper
> <andrew.cooper3@citrix.com>
Thanks,
Juergen
next prev parent reply other threads:[~2017-04-18 11:56 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-18 6:31 [PATCH v3 00/11] x86: xen cpuid() cleanup Juergen Gross
2017-04-18 6:31 ` [PATCH v3 01/11] xen: set cpu capabilities from xen_start_kernel() Juergen Gross
2017-04-18 6:31 ` [PATCH v3 02/11] x86/xen: don't indicate DCA support in pv domains Juergen Gross
2017-04-18 6:31 ` [PATCH v3 03/11] x86/xen: use capabilities instead of fake cpuid values for aperf Juergen Gross
2017-04-18 6:31 ` [PATCH v3 04/11] x86/xen: use capabilities instead of fake cpuid values for mtrr Juergen Gross
2017-04-18 6:31 ` [PATCH v3 05/11] x86/xen: use capabilities instead of fake cpuid values for acc Juergen Gross
2017-04-18 6:31 ` [PATCH v3 06/11] x86/xen: use capabilities instead of fake cpuid values for acpi Juergen Gross
2017-04-18 6:31 ` [PATCH v3 07/11] x86/xen: use capabilities instead of fake cpuid values for mwait Juergen Gross
2017-04-18 6:31 ` [PATCH v3 08/11] x86/xen: use capabilities instead of fake cpuid values for x2apic Juergen Gross
2017-04-18 6:31 ` [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave Juergen Gross
2017-04-18 10:02 ` [Xen-devel] " Andrew Cooper
2017-04-18 11:56 ` Juergen Gross [this message]
2017-04-21 14:24 ` Boris Ostrovsky
2017-04-21 14:38 ` Juergen Gross
2017-04-21 14:45 ` Andrew Cooper
2017-04-21 14:51 ` Boris Ostrovsky
2017-04-24 6:23 ` Juergen Gross
2017-04-18 6:31 ` [PATCH v3 10/11] vmware: set cpu capabilities during platform initialization Juergen Gross
2017-04-18 6:31 ` [PATCH v3 11/11] x86/cpu: remove hypervisor specific set_cpu_features Juergen Gross
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