Re: [RFC please check] KVM: question about the commit "Use Little Endian for Dirty Bitmap"

[Takuya Yoshikawa <yoshikawa.takuya-gVGce1chcLdL9jVzuh4AOg@public.gmane.org>]

(2010/04/21 15:07), Takuya Yoshikawa wrote:

> === not tested ===
> [PATCH sample] KVM: avoid to include an asm-generic bitops header file directly
>
> Including asm-generic bitops headers is kind of violation: there is no guarantee that
> no one will change those functions we are using.
>
> Signed-off-by: Takuya Yoshikawa<yoshikawatky-V2f5J/ArDKdQWUn/WH5d2uJTCWgwaB5pzw2xav70ESE@public.gmane.org>
Oh, I forgot to drop this line: this is made on my machine with not configured git.

Please ignore this Signed-off-by, the address is not valid.






> ---
>   virt/kvm/kvm_main.c |   17 +++++++++++++----
>   1 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 3725605..f029760 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -51,7 +51,6 @@
>   #include<asm/io.h>
>   #include<asm/uaccess.h>
>   #include<asm/pgtable.h>
> -#include<asm-generic/bitops/le.h>
>
>   #include "coalesced_mmio.h"
>
> @@ -1179,6 +1178,18 @@ int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len)
>   }
>   EXPORT_SYMBOL_GPL(kvm_clear_guest);
>
> +/*
> + * __set_le_bit is defined for ppc only.
> + */
> +static void kvm___set_le_bit(unsigned long nr, unsigned long *addr)
> +{
> +#ifdef __set_le_bit
> +	__set_le_bit(nr, addr);
> +#else
> +	__set_bit(nr, addr);
> +#endif
> +}
> +
>   void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
>   {
>   	struct kvm_memory_slot *memslot;
> @@ -1188,9 +1199,7 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
>   	if (memslot&&  memslot->dirty_bitmap) {
>   		unsigned long rel_gfn = gfn - memslot->base_gfn;
>
> -		/* avoid RMW */
> -		if (!generic_test_le_bit(rel_gfn, memslot->dirty_bitmap))
> -			generic___set_le_bit(rel_gfn, memslot->dirty_bitmap);
> +		kvm___set_le_bit(rel_gfn, memslot->dirty_bitmap);
>   	}
>   }
>