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authorJuergen Gross <jgross@suse.com>2017-04-25 09:47:40 +0300
committerJuergen Gross <jgross@suse.com>2017-05-05 11:43:10 +0300
commit40f4ac0b510dbf9f00668ded5474290940616d09 (patch)
tree89dda73f613f9f4083a1b493eb514160eeade45f /arch/x86/xen/enlighten_pv.c
parent3dbd8204af48d0da442f11ad39aa778a5fd462bf (diff)
downloadlinux-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>
Diffstat (limited to 'arch/x86/xen/enlighten_pv.c')
-rw-r--r--arch/x86/xen/enlighten_pv.c32
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);
}