From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:46011) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TIio2-00055s-B6 for qemu-devel@nongnu.org; Mon, 01 Oct 2012 12:25:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TIinx-00077H-5N for qemu-devel@nongnu.org; Mon, 01 Oct 2012 12:25:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42072) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TIinw-00076J-TD for qemu-devel@nongnu.org; Mon, 01 Oct 2012 12:25:13 -0400 Message-ID: <5069C3E3.8090702@redhat.com> Date: Mon, 01 Oct 2012 18:25:07 +0200 From: Pavel Hrdina MIME-Version: 1.0 References: <1347244257-15586-1-git-send-email-david@gibson.dropbear.id.au> <1347244257-15586-3-git-send-email-david@gibson.dropbear.id.au> <504DEAD1.3060908@suse.de> <20120912055706.GX12554@truffula.fritz.box> <50699E11.8020203@redhat.com> <871uhigtb3.fsf@codemonkey.ws> <5069B7F0.30300@redhat.com> <87txue2me7.fsf@codemonkey.ws> In-Reply-To: <87txue2me7.fsf@codemonkey.ws> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 2/2] cpu_physical_memory_write_rom() needs to do TB invalidates List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: David Gibson , qemu-devel@nongnu.org, =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= On 10/01/2012 06:21 PM, Anthony Liguori wrote: > Pavel Hrdina writes: > >> On 10/01/2012 04:28 PM, Anthony Liguori wrote: >>> Pavel Hrdina writes: >>> >>>> On 09/12/2012 07:57 AM, David Gibson wrote: >>>>> On Mon, Sep 10, 2012 at 03:27:45PM +0200, Andreas F=C3=A4rber wrote= : >>>>>> Am 10.09.2012 04:30, schrieb David Gibson: >>>>>>> cpu_physical_memory_write_rom(), despite the name, can also be us= ed to >>>>>>> write images into RAM - and will often be used that way if the ma= chine >>>>>>> uses load_image_targphys() into RAM addresses. >>>>>>> >>>>>>> However, cpu_physical_memory_write_rom(), unlike cpu_physical_mem= ory_rw() >>>>>>> does invalidate any cached TBs which might be affected by the reg= ion >>>>>> "doesn't"? >>>>>> >>>>>> Otherwise doesn't look wrong. >>>>> Oops, comment updated. >>>>> >>>>> From 6b913afaf83f52ee787271827c84b492e8ac5895 Mon Sep 17 00:00:0= 0 2001 >>>>> From: David Gibson >>>>> Date: Wed, 22 Aug 2012 14:58:04 +1000 >>>>> Subject: [PATCH] cpu_physical_memory_write_rom() needs to do TB inv= alidates >>>>> >>>>> 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 mach= ine >>>>> 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 mi= ght >>>>> be affected by the region written. >>>>> >>>>> This was breaking reset (under full emu) on the pseries machine - w= e loaded >>>>> our firmware image into RAM, and while executing it rewrite the cod= e 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 >>>>> --- >>>>> 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_ph= ys_addr_t addr, >>>>> /* ROM/RAM case */ >>>>> ptr =3D 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 -=3D l; >>>> Hi, >>>> >>>> this patch breaks Windows XP guest at all. Windows XP boot ends in l= oob >>>> 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=3D/data/data-shared/images/winxp-test.img -vnc 0.0.0.0:0 >>> Does changing the tb_invalidate_phys_page_range() call to: >>> >>> tb_invalidate_phys_page_range(addr1, addr1 + MAX(l, TARGET_PAGE_SIZE)= , 0); >>> >>> The dirty flag is being reset for the full page but we're potentially >>> only invalidating a subset of TBs that occur on the page. >>> >>> Regards, >>> >>> Anthony Liguori >>> >> No, it doesn't fix this bug. > Then I'm confused... invalidating TBs should never have a functional > impact IIUC. Are you confident in your bisection? Reverting this patc= h > fixes the problem? > > Regards, > > Anthony Liguori Yes I'm 100% sure that this commit cause this bug. I've tried to revert=20 this patch and it works OK. Pavel >> Pavel >> >>>> Pavel >