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-   -   Revert "UBUNTU: SAUCE: Mask CR4 writes on older Xen hypervisors" (http://www.linux-archive.org/ubuntu-kernel-team/704740-revert-ubuntu-sauce-mask-cr4-writes-older-xen-hypervisors.html)

Stefan Bader 09-17-2012 03:27 PM

Revert "UBUNTU: SAUCE: Mask CR4 writes on older Xen hypervisors"
 
This reverts commit d0ffa571dbcf13787baa52a31bc7b7025749d4b4 as
it seems unnecessary.

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---
arch/x86/xen/enlighten.c | 17 +----------------
1 file changed, 1 insertion(+), 16 deletions(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 108d943..ff962d4 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -196,18 +196,6 @@ void xen_vcpu_restore(void)
}
}

-/*
- * Older (with no clear statement about what old means) Xen hypervisors
- * will crash a PV guest that tries to store OSXSAVE into CR4.
- * To prevent this, we force the feature bits related to this off in the
- * xen cpuid call. This inline function serves as a centralized test
- * on whether the quirk should be done.
- */
-static inline needs_xsave_quirk(unsigned version)
-{
- return (xen_pv_domain() && ((version >> 16) < 4)) ? 1 : 0;
-}
-
static void __init xen_banner(void)
{
unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL);
@@ -219,8 +207,6 @@ static void __init xen_banner(void)
printk(KERN_INFO "Xen version: %d.%d%s%s
",
version >> 16, version & 0xffff, extra.extraversion,
xen_feature(XENFEAT_mmu_pt_update_preserve_ad) ? " (preserve-AD)" : "");
- if (needs_xsave_quirk(version))
- printk(KERN_INFO "Forcing xsave off due to Xen version.
");
}

#define CPUID_THERM_POWER_LEAF 6
@@ -351,7 +337,6 @@ static bool __init xen_check_mwait(void)
}
static void __init xen_init_cpuid_mask(void)
{
- unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL);
unsigned int ax, bx, cx, dx;
unsigned int xsave_mask;

@@ -374,7 +359,7 @@ static void __init xen_init_cpuid_mask(void)
(1 << (X86_FEATURE_OSXSAVE % 32));

/* Xen will set CR4.OSXSAVE if supported and not disabled by force */
- if (((cx & xsave_mask) != xsave_mask) || needs_xsave_quirk(version))
+ if ((cx & xsave_mask) != xsave_mask)
cpuid_leaf1_ecx_mask &= ~xsave_mask; /* disable XSAVE & OSXSAVE */
if (xen_check_mwait())
cpuid_leaf1_ecx_set_mask = (1 << (X86_FEATURE_MWAIT % 32));
--
1.7.9.5


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