xen: use hypercall rather than clts

Xen will trap and emulate clts, but its better to use a hypercall.
Also, xenner doesn't handle clts.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 33 insertions, 2 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index a05b7721bc81..446f4cd649e6 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -607,6 +607,30 @@ static void xen_flush_tlb_others(const cpumask_t *cpus, struct mm_struct *mm,
         xen_mc_issue(PARAVIRT_LAZY_MMU);
 }
 
+static void xen_clts(void)
+{
+        struct multicall_space mcs;
+
+        mcs = xen_mc_entry(0);
+
+        MULTI_fpu_taskswitch(mcs.mc, 0);
+
+        xen_mc_issue(PARAVIRT_LAZY_CPU);
+}
+
+static void xen_write_cr0(unsigned long cr0)
+{
+        struct multicall_space mcs;
+
+        /* Only pay attention to cr0.TS; everything else is
+           ignored. */
+        mcs = xen_mc_entry(0);
+
+        MULTI_fpu_taskswitch(mcs.mc, (cr0 & X86_CR0_TS) != 0);
+
+        xen_mc_issue(PARAVIRT_LAZY_CPU);
+}
+
 static void xen_write_cr2(unsigned long cr2)
 {
         x86_read_percpu(xen_vcpu)->arch.cr2 = cr2;
@@ -978,10 +1002,10 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = {
         .set_debugreg = xen_set_debugreg,
         .get_debugreg = xen_get_debugreg,
 
-        .clts = native_clts,
+        .clts = xen_clts,
 
         .read_cr0 = native_read_cr0,
-        .write_cr0 = native_write_cr0,
+        .write_cr0 = xen_write_cr0,
 
         .read_cr4 = native_read_cr4,
         .read_cr4_safe = native_read_cr4_safe,
diff --git a/include/asm-x86/xen/hypercall.h b/include/asm-x86/xen/hypercall.h
index c2ccd997ed35..897ff79cca3b 100644
--- a/include/asm-x86/xen/hypercall.h
+++ b/include/asm-x86/xen/hypercall.h
@@ -315,6 +315,13 @@ HYPERVISOR_nmi_op(unsigned long op, unsigned long arg)
 }
 
 static inline void
+MULTI_fpu_taskswitch(struct multicall_entry *mcl, int set)
+{
+        mcl->op = __HYPERVISOR_fpu_taskswitch;
+        mcl->args[0] = set;
+}
+
+static inline void
 MULTI_update_va_mapping(struct multicall_entry *mcl, unsigned long va,
                         pte_t new_val, unsigned long flags)
 {