On 2014/11/14 18:06, Paolo Bonzini wrote:
On 14/11/2014 10:31, Tiejun Chen wrote:
In some real scenarios 'start' may not be less than 'end' like
maxphyaddr = 52.
Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
---
arch/x86/kvm/mmu.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index bde8ee7..0e98b5e 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -58,6 +58,8 @@
static inline u64 rsvd_bits(int s, int e)
{
+ if (unlikely(s > e))
+ return 0;
return ((1ULL << (e - s + 1)) - 1) << s;
}
s == e + 1 is supported:
(1ULL << (e - (e + 1) + 1)) - 1) << s ==
(1ULL << (e - (e + 1) + 1)) - 1) << s
= (1ULL << (e - e - 1) + 1)) - 1) << s
= (1ULL << (-1) + 1)) - 1) << s
= (1ULL << (0) - 1) << s
= (1ULL << (- 1) << s
Am I missing something?
Thanks
Tiejun
(1ULL << 0) << s ==
0
Is there any case where s is even bigger?
Paolo
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