[Xen-devel] [PATCH V8 1/2] x86/xsaves: fix two miscellaneous issues

[Shuai Ruan <shuai.ruan@xxxxxxxxxxxxxxx>]

From: Shuai Ruan <shuai.ruan@xxxxxxxxx>

1. get_xsave_addr() will only be called when
xsave_area_compressed(xsave) is true. So drop the
conditional expression.

2. expand_xsave_states() will memset the area when
get NULL from get_xsave_addr().

Reported-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Shuai Ruan <shuai.ruan@xxxxxxxxx>
---
v2: Address comments from Jan:
1. Add assert in get_xsave_addr.

 xen/arch/x86/xstate.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c
index 8c652bc..047ac74 100644
--- a/xen/arch/x86/xstate.c
+++ b/xen/arch/x86/xstate.c
@@ -164,12 +164,9 @@ static void *get_xsave_addr(struct xsave_struct *xsave,
                             const uint16_t *comp_offsets,
                             unsigned int xfeature_idx)
 {
-    if ( !((1ul << xfeature_idx) & xsave->xsave_hdr.xstate_bv) )
-        return NULL;
-
-    return (void *)xsave + (xsave_area_compressed(xsave) ?
-                            comp_offsets[xfeature_idx] :
-                            xstate_offsets[xfeature_idx]);
+    ASSERT(xsave_area_compressed(xsave));
+    return (1ul << xfeature_idx) & xsave->xsave_hdr.xstate_bv ?
+           (void *)xsave + comp_offsets[xfeature_idx] : NULL;
 }
 
 void expand_xsave_states(struct vcpu *v, void *dest, unsigned int size)
@@ -211,6 +208,8 @@ void expand_xsave_states(struct vcpu *v, void *dest, 
unsigned int size)
             ASSERT((xstate_offsets[index] + xstate_sizes[index]) <= size);
             memcpy(dest + xstate_offsets[index], src, xstate_sizes[index]);
         }
+        else
+            memset(dest + xstate_offsets[index], 0, xstate_sizes[index]);
 
         valid &= ~feature;
     }
-- 
1.9.1


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