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Date: Mon, 4 Nov 2013 08:15:56 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20131104061556.GA3365@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] exec: limit system memory size
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To: marcel.a@redhat.com, qemu-devel@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>, Jan Kiszka <jan.kiszka@siemens.com>, qemu-stable@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, Andreas =?iso-8859-1?Q?F=E4rber?= <afaerber@suse.de>, Richard Henderson <rth@twiddle.net>

On Mon, Nov 04, 2013 at 08:06:08AM +0200, Michael S. Tsirkin wrote:
> The page table logic in exec.c assumes
> that memory addresses are at most TARGET_PHYS_ADDR_SPACE_BITS.
> 
> But pci addresses are full 64 bit so if we try to render them ignoring
> the extra bits, we get strange effects with sections overlapping each
> other.
> 
> To fix, simply limit the system memory size to
>  1 << TARGET_PHYS_ADDR_SPACE_BITS,
> pci addresses will be rendered within that.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

BTW I think this is -stable material too.

> ---
>  exec.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/exec.c b/exec.c
> index 030118e..c7a8df5 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1801,7 +1801,12 @@ void address_space_destroy_dispatch(AddressSpace *as)
>  static void memory_map_init(void)
>  {
>      system_memory = g_malloc(sizeof(*system_memory));
> -    memory_region_init(system_memory, NULL, "system", INT64_MAX);
> +
> +    assert(TARGET_PHYS_ADDR_SPACE_BITS <= 64);
> +
> +    memory_region_init(system_memory, NULL, "system",
> +                       TARGET_PHYS_ADDR_SPACE_BITS == 64 ?
> +                       UINT64_MAX : (0x1ULL << TARGET_PHYS_ADDR_SPACE_BITS));
>      address_space_init(&address_space_memory, system_memory, "memory");
>  
>      system_io = g_malloc(sizeof(*system_io));
> -- 
> MST