From: Andrea Arcangeli <andrea@qumranet.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@qumranet.com>, kvm-devel <kvm@vger.kernel.org>
Subject: Re: KVM: MMU: large page update_pte issue with non-PAE 32-bit guests
Date: Tue, 10 Jun 2008 00:33:49 +0200 [thread overview]
Message-ID: <20080609223349.GQ8047@duo.random> (raw)
In-Reply-To: <20080609023549.GA11092@dmt.cnet>
On Sun, Jun 08, 2008 at 11:35:49PM -0300, Marcelo Tosatti wrote:
>
> kvm_mmu_pte_write() does not handle 32-bit non-PAE large page backed
> guests properly. It will instantiate two 2MB sptes pointing to the same
> physical 2MB page when a guest large pte update is trapped.
>
> Instead of duplicating code to handle this, disallow directory level
> updates to happen through kvm_mmu_pte_write(), so the two 2MB sptes
> emulating one guest 4MB pte can be correctly created by the page fault
> handling path.
This fix reminded me of this stack trace I looked some time ago, it
was also related to a 4M user pte IIRC, may they be related? In such a
case we can should update the bug status.
http://sourceforge.net/tracker/index.php?func=detail&aid=1929279&group_id=180599&atid=893831
7916:Mar 30 11:18:59 hmf kernel: RIP: 0010:[<ffffffff8882c99d>] [<ffffffff8882c99d>] :kvm:rmap_remove+0x12d/0x1e0
7917:Mar 30 11:18:59 hmf kernel: RSP: 0018:ffff8100715a1a98 EFLAGS: 00010296
7918:Mar 30 11:18:59 hmf kernel: RAX: 0000000000000031 RBX: ffff810001a62f98 RCX: ffffffff80b04168
7919:Mar 30 11:18:59 hmf kernel: RDX: ffffffff80b04168 RSI: 0000000000000006 RDI: ffffffff80b04160
7920:Mar 30 11:18:59 hmf kernel: RBP: ffff810005fb2000 R08: 000000e1aeb7ed38 R09: 0000000000000000
7921:Mar 30 11:18:59 hmf kernel: R10: ffff810002c13b60 R11: 0000000000000001 R12: ffff810039518b30
7922:Mar 30 11:18:59 hmf kernel: R13: ffff81007cc78000 R14: 000000002f7b5063 R15: ffff810039518b30
7923:Mar 30 11:18:59 hmf kernel: FS: 00000000ffdff000(0000) GS:ffffffff80b8f000(0000) knlGS:0000000000000000
7924:Mar 30 11:18:59 hmf kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
7925:Mar 30 11:18:59 hmf kernel: CR2: 00002aaaaaafb000 CR3: 000000007dfc0000 CR4: 00000000000006e0
7926:Mar 30 11:18:59 hmf kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
7927:Mar 30 11:18:59 hmf kernel: DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
7928:Mar 30 11:18:59 hmf kernel: Process qemu-system-x86 (pid: 6262, threadinfo ffff8100715a0000, task ffff81000e90a810)
7929:Mar 30 11:18:59 hmf kernel: Stack: ffff810079af4fa0 0000000000000000 ffff810005fb2000 ffff81000e99c040
7930:Mar 30 11:18:59 hmf kernel: ffff81000e99c040 ffffffff8882e870 00000000040df863 ffffffff8882f3fe
7931:Mar 30 11:18:59 hmf kernel: ffff810000000001 000000000000000f 0000000000000000 00000000c0600000
7932:Mar 30 11:18:59 hmf kernel: Call Trace:
7933:Mar 30 11:18:59 hmf kernel: [<ffffffff8882e870>] :kvm:kvm_mmu_pte_write+0x220/0x850
7934:Mar 30 11:18:59 hmf kernel: [<ffffffff8882f3fe>] :kvm:paging64_walk_addr+0x29e/0x340
7935:Mar 30 11:18:59 hmf kernel: [<ffffffff88827cf4>] :kvm:__emulator_write_phys+0x44/0x70
7936:Mar 30 11:18:59 hmf kernel: [<ffffffff8882966a>] :kvm:emulator_write_emulated_onepage+0xba/0x150
7937:Mar 30 11:18:59 hmf kernel: [<ffffffff88831819>] :kvm:x86_emulate_insn+0x419/0x4430
7938:Mar 30 11:18:59 hmf kernel: [<ffffffff8884716b>] :kvm_amd:svm_get_segment+0xb/0xa0
7939:Mar 30 11:18:59 hmf kernel: [<ffffffff888264ee>] :kvm:kvm_get_cs_db_l_bits+0x1e/0x40
7940:Mar 30 11:18:59 hmf kernel: [<ffffffff88827b4f>] :kvm:emulate_instruction+0x1df/0x340
7941:Mar 30 11:18:59 hmf kernel: [<ffffffff8882e618>] :kvm:kvm_mmu_page_fault+0x58/0x90
Thanks!
next prev parent reply other threads:[~2008-06-09 22:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-09 2:35 KVM: MMU: large page update_pte issue with non-PAE 32-bit guests Marcelo Tosatti
2008-06-09 22:33 ` Andrea Arcangeli [this message]
2008-06-10 16:44 ` Marcelo Tosatti
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