[Qemu-devel] Re: [PATCH 6/7] Set slots more carefully

[Jan Kiszka <jan.kiszka@siemens.com>]

Alexander Graf wrote:
> KVM only supports slot sizes of PAGE_SIZE granilarity. On PPC the OS
> sets the framebuffer to some odd size though, causing the current code
> to simply abort().
> 
> So let's bet graceful here. We can just allocate memory sizes that are of
> PAGE_SIZE granularity and everything that exceeds that comes in as MMIO and
> gets handled too - just slower.
> 
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  kvm-all.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kvm-all.c b/kvm-all.c
> index 961fa32..60b76cf 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -134,7 +134,7 @@ static int kvm_set_user_memory_region(KVMState *s, KVMSlot *slot)
>  
>      mem.slot = slot->slot;
>      mem.guest_phys_addr = slot->start_addr;
> -    mem.memory_size = slot->memory_size;
> +    mem.memory_size = slot->memory_size & ~(TARGET_PAGE_SIZE - 1);

TARGET_PAGE_MASK? And I bet you want to round up here...

Does the caller use the odd size consistently (i.e. also for dirty log
enable/disable)? Otherwise we may run into troubles while looking up
that slot as it will be registered in user space via its odd end
address. Not sure yet, but maybe it's better to round up at the call
sites of kvm_set_user_memory_region.

Jan

-- 
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