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--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -168,21 +168,23 @@ static void __init xen_banner(void)
xen_feature(XENFEAT_mmu_pt_update_preserve_ad) ? " (preserve-AD)" : "");
}
+static __read_mostly unsigned int cpuid_leaf1_edx_mask = ~0;
+static __read_mostly unsigned int cpuid_leaf1_ecx_mask = ~0;
+
static void xen_cpuid(unsigned int *ax, unsigned int *bx,
unsigned int *cx, unsigned int *dx)
{
+ unsigned maskecx = ~0;
unsigned maskedx = ~0;
/*
* Mask out inconvenient features, to try and disable as many
* unsupported kernel subsystems as possible.
*/
- if (*ax == 1)
- maskedx = ~((1 << X86_FEATURE_APIC) | /* disable APIC */
- (1 << X86_FEATURE_ACPI) | /* disable ACPI */
- (1 << X86_FEATURE_MCE) | /* disable MCE */
- (1 << X86_FEATURE_MCA) | /* disable MCA */
- (1 << X86_FEATURE_ACC)); /* thermal monitoring */
+ if (*ax == 1) {
+ maskecx = cpuid_leaf1_ecx_mask;
+ maskedx = cpuid_leaf1_edx_mask;
+ }
asm(XEN_EMULATE_PREFIX "cpuid"
: "=a" (*ax),
@@ -190,9 +192,43 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
"=c" (*cx),
"=d" (*dx)
: "0" (*ax), "2" (*cx));
+
+ *cx &= maskecx;
*dx &= maskedx;
}
+static __init void xen_init_cpuid_mask(void)
+{
+ unsigned int ax, bx, cx, dx;
+
+ cpuid_leaf1_edx_mask =
+ ~((1 << X86_FEATURE_MCE) | /* disable MCE */
+ (1 << X86_FEATURE_MCA) | /* disable MCA */
+ (1 << X86_FEATURE_ACC)); /* thermal monitoring */
+
+ if (!xen_initial_domain())
+ cpuid_leaf1_edx_mask &=
+ ~((1 << X86_FEATURE_APIC) | /* disable local APIC */
+ (1 << X86_FEATURE_ACPI)); /* disable ACPI */
+
+ ax = 1;
+ 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);
+ }
+}
+
static void xen_set_debugreg(int reg, unsigned long val)
{
HYPERVISOR_set_debugreg(reg, val);
@@ -903,6 +939,8 @@ asmlinkage void __init xen_start_kernel(void)
xen_init_irq_ops();
+ xen_init_cpuid_mask();
+
#ifdef CONFIG_X86_LOCAL_APIC
/*
* set up the basic apic ops.
|