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xen: just completely disable XSAVE

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Some (old) versions of Xen just kill the domain if it tries to set any
unknown bits in CR4, so we can't reliably probe for OSXSAVE in
CR4.

Since Xen doesn't support XSAVE for guests at the moment, and no such
support is being worked on, there's no downside in just unconditionally
masking XSAVE support.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Jeremy Fitzhardinge 2010-09-18 22:25:30 -07:00 committed by Konrad Rzeszutek Wilk
parent d88885d092
commit 61f4237d5b
1 changed files with 1 additions and 17 deletions
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18
arch/x86/xen/enlighten.c
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@ -250,23 +250,7 @@ static __init void xen_init_cpuid_mask(void)
~((1 << X86_FEATURE_APIC) | /* disable local APIC */
(1 << X86_FEATURE_ACPI)); /* disable ACPI */
ax = 1;
cx = 0;
xen_cpuid(&ax, &bx, &cx, &dx);
/* cpuid claims we support xsave; try enabling it to see what happens */
if (cx & (1 << (X86_FEATURE_XSAVE % 32))) {
unsigned long cr4;
set_in_cr4(X86_CR4_OSXSAVE);
cr4 = read_cr4();
if ((cr4 & X86_CR4_OSXSAVE) == 0)
cpuid_leaf1_ecx_mask &= ~(1 << (X86_FEATURE_XSAVE % 32));
clear_in_cr4(X86_CR4_OSXSAVE);
}
cpuid_leaf1_ecx_mask &= ~(1 << (X86_FEATURE_XSAVE % 32)); /* disable XSAVE */
}
static void xen_set_debugreg(int reg, unsigned long val)