Re: [Qemu-devel] [PATCH 2/2] cpu_physical_memory_write_rom() needs to do TB invalidates

[Pavel Hrdina <phrdina@redhat.com>]

On 09/12/2012 07:57 AM, David Gibson wrote:
> On Mon, Sep 10, 2012 at 03:27:45PM +0200, Andreas Färber wrote:
>> Am 10.09.2012 04:30, schrieb David Gibson:
>>> cpu_physical_memory_write_rom(), despite the name, can also be used to
>>> write images into RAM - and will often be used that way if the machine
>>> uses load_image_targphys() into RAM addresses.
>>>
>>> However, cpu_physical_memory_write_rom(), unlike cpu_physical_memory_rw()
>>> does invalidate any cached TBs which might be affected by the region
>> "doesn't"?
>>
>> Otherwise doesn't look wrong.
> Oops, comment updated.
>
>  From 6b913afaf83f52ee787271827c84b492e8ac5895 Mon Sep 17 00:00:00 2001
> From: David Gibson <david@gibson.dropbear.id.au>
> Date: Wed, 22 Aug 2012 14:58:04 +1000
> Subject: [PATCH] cpu_physical_memory_write_rom() needs to do TB invalidates
>
> cpu_physical_memory_write_rom(), despite the name, can also be used to
> write images into RAM - and will often be used that way if the machine
> uses load_image_targphys() into RAM addresses.
>
> However, cpu_physical_memory_write_rom(), unlike
> cpu_physical_memory_rw() doesn't invalidate any cached TBs which might
> be affected by the region written.
>
> This was breaking reset (under full emu) on the pseries machine - we loaded
> our firmware image into RAM, and while executing it rewrite the code at
> the entry point (correctly causing a TB invalidate/refresh).  When we
> reset the firmware image was reloaded, but the TB from the rewrite was
> still active and caused us to get an illegal instruction trap.
>
> This patch fixes the bug by duplicating the tb invalidate code from
> cpu_physical_memory_rw() in cpu_physical_memory_write_rom().
>
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>   exec.c |    7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/exec.c b/exec.c
> index 5834766..eff40d7 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -3523,6 +3523,13 @@ void cpu_physical_memory_write_rom(target_phys_addr_t addr,
>               /* ROM/RAM case */
>               ptr = qemu_get_ram_ptr(addr1);
>               memcpy(ptr, buf, l);
> +            if (!cpu_physical_memory_is_dirty(addr1)) {
> +                /* invalidate code */
> +                tb_invalidate_phys_page_range(addr1, addr1 + l, 0);
> +                /* set dirty bit */
> +                cpu_physical_memory_set_dirty_flags(
> +                    addr1, (0xff & ~CODE_DIRTY_FLAG));
> +            }
>               qemu_put_ram_ptr(ptr);
>           }
>           len -= l;
Hi,

this patch breaks Windows XP guest at all. Windows XP boot ends in loob 
by restarting itself after time-out expires in windows advanced boot 
options.

I started the guest using this command-line:

./x86_64-softmmu/qemu-system-x86_64 -m 2G -drive 
file=/data/data-shared/images/winxp-test.img -vnc 0.0.0.0:0

Pavel