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| author | Juergen Gross <jgross@suse.com> | 2017-04-25 09:47:40 +0300 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2017-05-05 11:43:10 +0300 |
| commit | 40f4ac0b510dbf9f00668ded5474290940616d09 (patch) | |
| tree | 89dda73f613f9f4083a1b493eb514160eeade45f | |
| parent | 3dbd8204af48d0da442f11ad39aa778a5fd462bf (diff) | |
| download | linux-40f4ac0b510dbf9f00668ded5474290940616d09.tar.xz | |
x86/xen: fix xsave capability setting
Commit 690b7f10b4f9f ("x86/xen: use capabilities instead of fake cpuid
values for xsave") introduced a regression as it tried to make use of
the fixup feature before it being available.
Fall back to the old variant testing via cpuid().
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
| -rw-r--r-- | arch/x86/xen/enlighten_pv.c | 32 |
1 files changed, 9 insertions, 23 deletions
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index a732bc2b9dfc..a1af4f68278f 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -277,26 +277,15 @@ static bool __init xen_check_mwait(void) static bool __init xen_check_xsave(void) { - unsigned int err, eax, edx; + unsigned int cx, xsave_mask; - /* - * 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. - */ - 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)); - - return err == 0; + cx = cpuid_ecx(1); + + xsave_mask = (1 << (X86_FEATURE_XSAVE % 32)) | + (1 << (X86_FEATURE_OSXSAVE % 32)); + + /* Xen will set CR4.OSXSAVE if supported and not disabled by force */ + return (cx & xsave_mask) == xsave_mask; } static void __init xen_init_capabilities(void) @@ -317,10 +306,7 @@ static void __init xen_init_capabilities(void) else setup_clear_cpu_cap(X86_FEATURE_MWAIT); - if (xen_check_xsave()) { - setup_force_cpu_cap(X86_FEATURE_XSAVE); - setup_force_cpu_cap(X86_FEATURE_OSXSAVE); - } else { + if (!xen_check_xsave()) { setup_clear_cpu_cap(X86_FEATURE_XSAVE); setup_clear_cpu_cap(X86_FEATURE_OSXSAVE); } |