From: Avi Kivity <avi@redhat.com>
To: Joerg Roedel <joerg.roedel@amd.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] KVM: Remove unnecessary divide operations
Date: Thu, 01 Jul 2010 17:18:13 +0300 [thread overview]
Message-ID: <4C2CA3A5.2040802@redhat.com> (raw)
In-Reply-To: <1277992812-31945-2-git-send-email-joerg.roedel@amd.com>
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
next prev parent reply other threads:[~2010-07-01 14:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-01 14:00 [PATCH 0/2] Use u64 for gfn_t in KVM Joerg Roedel
2010-07-01 14:00 ` [PATCH 1/2] KVM: Remove unnecessary divide operations Joerg Roedel
2010-07-01 14:18 ` Avi Kivity [this message]
2010-07-01 14:00 ` [PATCH 2/2] KVM: Use u64 for frame data types Joerg Roedel
2010-07-01 14:18 ` [PATCH 0/2] Use u64 for gfn_t in KVM Avi Kivity
2010-07-02 17:19 ` Marcelo Tosatti
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