x86: Avoid calling xsave_alloc_save_area before xsave_init

Currently, xsave_alloc_save_area will be called in
init_idle_domain->scheduler_init->alloc_vcpu->vcpu_initialise calls
with xsave_cntxt_size=0, it is earlier than xsave_init called in
identity_cpu(). This may causing buffer overflow on xmem_pool.

Idle domain isn't using FPU,SSE,AVX or any such extended state and
doesn't need it saved. xsave_{alloc,free}_save_area() should
test-and-exit on is_idle_vcpu(), and our context switch code should
not be doing XSAVE when switching out an idle vcpu.

Signed-off-by: Wei Gang <gang.wei@intel.com>
Signed-off-by: Keir Fraser <keir@xen.org>

1 files changed, 1 insertions, 31 deletions

diff --git a/xen/include/asm-x86/i387.h b/xen/include/asm-x86/i387.h
index 4cb67d482c..8b4e9ce1bd 100644
--- a/xen/include/asm-x86/i387.h
+++ b/xen/include/asm-x86/i387.h
@@ -110,6 +110,7 @@ static inline void xrstor(struct vcpu *v)
         : "m" (*ptr), "a" (-1), "d" (-1), "D"(ptr));
 }
 
+extern void setup_fpu(struct vcpu *v);
 extern void init_fpu(void);
 extern void save_init_fpu(struct vcpu *v);
 extern void restore_fpu(struct vcpu *v);
@@ -124,35 +125,4 @@ extern void restore_fpu(struct vcpu *v);
     __asm__ __volatile__ ( "ldmxcsr %0" : : "m" (__mxcsr) );    \
 } while ( 0 )
 
-static inline void setup_fpu(struct vcpu *v)
-{
-    /* Avoid recursion. */
-    clts();
-
-    if ( !v->fpu_dirtied )
-    {
-        v->fpu_dirtied = 1;
-        if ( cpu_has_xsave )
-        {
-            if ( !v->fpu_initialised )
-                v->fpu_initialised = 1;
-
-            /* XCR0 normally represents what guest OS set. In case of Xen
-             * itself, we set all supported feature mask before doing
-             * save/restore.
-             */
-            set_xcr0(v->arch.xcr0_accum);
-            xrstor(v);
-            set_xcr0(v->arch.xcr0);
-        }
-        else
-        {
-            if ( v->fpu_initialised )
-                restore_fpu(v);
-            else
-                init_fpu();
-        }
-    }
-}
-
 #endif /* __ASM_I386_I387_H */