[Xen-devel] [PATCH v5 1/3] xsave: fix initialization of FPU memory area

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

When the CPU supports XSAVE, the initialization of the FPU memory area is
done during allocation of the XSAVE area. This is different from the way
it's done in non-xsave capable CPUs, so unify both paths and always
initialise the FPU state in vcpu_restore_fpu_lazy.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/i387.c   | 2 +-
 xen/arch/x86/xstate.c | 8 --------
 2 files changed, 1 insertion(+), 9 deletions(-)

diff --git a/xen/arch/x86/i387.c b/xen/arch/x86/i387.c
index b661d39..fcd87a6 100644
--- a/xen/arch/x86/i387.c
+++ b/xen/arch/x86/i387.c
@@ -226,7 +226,7 @@ void vcpu_restore_fpu_lazy(struct vcpu *v)
     if ( v->fpu_dirtied )
         return;
 
-    if ( cpu_has_xsave )
+    if ( cpu_has_xsave && v->fpu_initialised )
         fpu_xrstor(v, XSTATE_LAZY);
     else if ( v->fpu_initialised )
         fpu_fxrstor(v);
diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c
index b65da38..8007342 100644
--- a/xen/arch/x86/xstate.c
+++ b/xen/arch/x86/xstate.c
@@ -415,14 +415,6 @@ int xstate_alloc_save_area(struct vcpu *v)
     if ( save_area == NULL )
         return -ENOMEM;
 
-    /*
-     * Set the memory image to default values, but don't force the context
-     * to be loaded from memory (i.e. keep save_area->xsave_hdr.xstate_bv
-     * clear).
-     */
-    save_area->fpu_sse.fcw = FCW_DEFAULT;
-    save_area->fpu_sse.mxcsr = MXCSR_DEFAULT;
-
     v->arch.xsave_area = save_area;
     v->arch.xcr0 = 0;
     v->arch.xcr0_accum = 0;
-- 
1.9.5 (Apple Git-50.3)


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