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Re: [Qemu-ppc] [PATCH] kvm: fix incorrect length in a loop over kvm dirt
From: |
Alexander Graf |
Subject: |
Re: [Qemu-ppc] [PATCH] kvm: fix incorrect length in a loop over kvm dirty pages map |
Date: |
Tue, 20 Nov 2012 10:06:02 +0100 |
On 20.11.2012, at 02:40, Alexey Kardashevskiy wrote:
> QEMU allocates a map enough for 4k pages. However the system page size
> can be 64K (for example on POWER) and the host kernel uses only a small
> part of it as one big stores a dirty flag for 16 pages 4K each,
> the hpratio variable stores this ratio and
> the kvm_get_dirty_pages_log_range function handles it correctly.
>
> However kvm_get_dirty_pages_log_range still goes beyond the data
> provided by the host kernel which is not correct. It does not cause
> errors at the moment as the whole bitmap is zeroed before doing KVM ioctl.
>
> The patch reduces number of iterations over the map.
>
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
While at at, could you please also double-check whether the coalesced mmio code
does the right thing? It also uses TARGET_PAGE_SIZE, which looks bogus to me.
Since we don't support coalesced mmio (yet), it's not too big of a deal, but
it'd be nice to get right.
Thanks, applied to ppc-next.
Alex
> ---
> kvm-all.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kvm-all.c b/kvm-all.c
> index b6d0483..c99997f 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -364,7 +364,7 @@ static int
> kvm_get_dirty_pages_log_range(MemoryRegionSection *section,
> unsigned int i, j;
> unsigned long page_number, c;
> hwaddr addr, addr1;
> - unsigned int len = ((section->size / TARGET_PAGE_SIZE) + HOST_LONG_BITS
> - 1) / HOST_LONG_BITS;
> + unsigned int len = ((section->size / getpagesize()) + HOST_LONG_BITS -
> 1) / HOST_LONG_BITS;
> unsigned long hpratio = getpagesize() / TARGET_PAGE_SIZE;
>
> /*
> --
> 1.7.10.4
>
>