From patchwork Fri Sep 21 15:28:03 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [Lucid,1/2,SRU] xen: just completely disable XSAVE Date: Fri, 21 Sep 2012 05:28:03 -0000 From: Stefan Bader X-Patchwork-Id: 185786 Message-Id: <1348241284-14489-4-git-send-email-stefan.bader@canonical.com> To: kernel-team@lists.ubuntu.com From: Jeremy Fitzhardinge 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 Signed-off-by: Konrad Rzeszutek Wilk BugLink: http://bugs.launchpad.net/bugs/1044550 (cherry-picked from commit 61f4237d5b005767a76f4f3694e68e6f78f392d9 upstream) Signed-off-by: Stefan Bader --- arch/x86/xen/enlighten.c | 18 +----------------- 1 file changed, 1 insertion(+), 17 deletions(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index c8e72dd..e66c9ce 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -224,23 +224,7 @@ 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)