diff options
Diffstat (limited to 'arch/x86/xen/enlighten.c')
| -rw-r--r-- | arch/x86/xen/enlighten.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index ff962d4b821..108d943649c 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -196,6 +196,18 @@ 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); @@ -207,6 +219,8 @@ static void __init xen_banner(void) printk(KERN_INFO "Xen version: %d.%d%s%s\n", 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.\n"); } #define CPUID_THERM_POWER_LEAF 6 @@ -337,6 +351,7 @@ 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; @@ -359,7 +374,7 @@ 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) + if (((cx & xsave_mask) != xsave_mask) || needs_xsave_quirk(version)) cpuid_leaf1_ecx_mask &= ~xsave_mask; /* disable XSAVE & OSXSAVE */ if (xen_check_mwait()) cpuid_leaf1_ecx_set_mask = (1 << (X86_FEATURE_MWAIT % 32)); |