Messages in this thread | | | Date | Thu, 01 Jul 2010 17:18:13 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH 1/2] KVM: Remove unnecessary divide operations |
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On 07/01/2010 05:00 PM, Joerg Roedel wrote: > This patch converts unnecessary divide and modulo operations > in the KVM large page related code into logical operations. > This allows to convert gfn_t to u64 while not breaking 32 > bit builds. > > > #define KVM_NR_PAGE_SIZES 2 > -#define KVM_HPAGE_SHIFT(x) (PAGE_SHIFT + ((x) - 1) * 8) > +#define KVM_HPAGE_GFN_SHIFT(x) (((x) - 1) * 8) > +#define KVM_HPAGE_SHIFT(x) (PAGE_SHIFT + KVM_HPAGE_GFN_SHIFT(x)) > #define KVM_HPAGE_SIZE(x) (1UL<< KVM_HPAGE_SHIFT(x)) > #define KVM_HPAGE_MASK(x) (~(KVM_HPAGE_SIZE(x) - 1)) >
In theory, KVM_HPAGE_SIZE() needs s/1UL/(u64)1/, or KVM_HPAGE_MASK becomes truncated if used against a gfn_t. In practice, KVM_HPAGE_MASK is not used at all, so this doesn't matter.
-- error compiling committee.c: too many arguments to function
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