From: Juergen Gross <jgross@suse.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v3 09/11] x86/xen: use capabilities instead of fake cpuid values for xsave
Date: Fri, 21 Apr 2017 16:38:42 +0200 [thread overview]
Message-ID: <12028326-0f19-9430-d8b7-a376facf8749@suse.com> (raw)
In-Reply-To: <da6c4270-2123-5203-4e76-32f4b616242f@oracle.com>
On 21/04/17 16:24, Boris Ostrovsky wrote:
>
>> +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. */
>> + asm volatile("1: .byte 0x0f,0x01,0xd0\n\t" /* xgetbv */
>> + "xor %[err], %[err]\n"
>> + "2:\n\t"
>> + ".pushsection .fixup,\"ax\"\n\t"
>> + "3: movl $1,%[err]\n\t"
>> + "jmp 2b\n\t"
>> + ".popsection\n\t"
>> + _ASM_EXTABLE(1b, 3b)
>> + : [err] "=r" (err), "=a" (eax), "=d" (edx)
>> + : "c" (0));
>
> Have you tested this on processors where we actually trap on xgetbv?
>
> I have an AMD box without XSAVE support and this is a fatal error. I
> suspect it's too early to use exception fixup framework here.
Uuh, too bad.
Then I fear we must use the other solution Andrew didn't like. :-(
Andrew, would you be okay with that?
Juergen
next prev parent reply other threads:[~2017-04-21 14:38 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
2017-04-21 14:24 ` Boris Ostrovsky
2017-04-21 14:38 ` Juergen Gross [this message]
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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