On 09. 04. 20, 10:06, Gary Lin wrote: > On Thu, Apr 09, 2020 at 09:51:20AM +0200, Ard Biesheuvel wrote: >> On Wed, 8 Apr 2020 at 12:51, Jiri Slaby <jslaby@xxxxxxx> wrote: >>> >>> Ccing Gary. >>> >>> On 08. 04. 20, 12:47, Ard Biesheuvel wrote: >>>> On Wed, 8 Apr 2020 at 12:42, Jiri Slaby <jslaby@xxxxxxx> wrote: >>>>> >>>>> On 13. 01. 20, 18:22, Ard Biesheuvel wrote: >>>>>> The mixed mode thunking routine requires a part of it to be >>>>>> mapped 1:1, and for this reason, we currently map the entire >>>>>> kernel .text read/write in the EFI page tables, which is bad. >>>>>> >>>>>> In fact, the kernel_map_pages_in_pgd() invocation that installs >>>>>> this mapping is entirely redundant, since all of DRAM is already >>>>>> 1:1 mapped read/write in the EFI page tables when we reach this >>>>>> point, which means that .rodata is mapped read-write as well. >>>>>> >>>>>> So let's remap both .text and .rodata read-only in the EFI >>>>>> page tables. >>>>> >>>>> This patch causes unhandled page faults in mixed mode: >>>>> >>>>>> BUG: unable to handle page fault for address: 000000001557ee88 >>>>>> #PF: supervisor write access in kernel mode >>>>>> #PF: error_code(0x0003) - permissions violation >>>>>> PGD fd52063 P4D fd52063 PUD fd53063 PMD 154000e1 >>>>>> Oops: 0003 [#1] SMP PTI >>>>>> CPU: 1 PID: 191 Comm: systemd-escape Not tainted >>>>> 5.6.2-20.gb22bc26-default #1 openSUSE Tumbleweed (unreleased) >>>>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 >>>>> 02/06/2015 >>>>>> RIP: 0008:0x3d2eed95 >>>>>> Code: 8b 45 d4 8b 4d 10 8b 40 04 89 01 89 3b 50 6a 00 8b 55 0c 6a 00 >>>>> 8b 45 08 0f b6 4d e4 6a 01 31 f6 e8 ee c5 fc ff 83 c4 10 eb 07 <89> 03 >>>>> be 05 00 00 80 a1 74 63 31 3d 83 c0 48 e8 44 d2 ff ff eb 05 >>>>>> RSP: 0018:000000000fd66fa0 EFLAGS: 00010002 >>>>>> RAX: 0000000000000001 RBX: 000000001557ee88 RCX: 000000003d1f1120 >>>>>> RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000001 >>>>>> RBP: 000000000fd66fd8 R08: 000000001557ee88 R09: 0000000000000000 >>>>>> R10: 0000000000000055 R11: 0000000000000000 R12: 0000000015bcf000 >>>>>> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 >>>>>> FS: 00007f36ee9dc940(0000) GS:ffff9b903d700000(0000) >>>>> knlGS:0000000000000000 >>>>>> CS: 0008 DS: 0018 ES: 0018 CR0: 0000000080050033 >>>>>> CR2: 000000001557ee88 CR3: 000000000fd5e000 CR4: 00000000000006e0 >>>>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >>>>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >>>>>> Call Trace: >>>>>> Modules linked in: efivarfs >>>>>> CR2: 000000001557ee88 >>>>> >>>>> EFI apparently tries to write to now read-only memory. >>>>> >>>>> See: >>>>> https://bugzilla.suse.com/show_bug.cgi?id=1168645 >>>>> >>>>> Reverting it on the top of 5.6 fixes the issue. >>>>> >>>>> I am using >>>>> /usr/share/qemu/ovmf-ia32-code.bin >>>>> /usr/share/qemu/ovmf-ia32-vars.bin >>>>> from qemu-ovmf-ia32-202002-1.1.noarch rpm. >>>>> >>>> >>>> Do you have a git tree for Suse's OVMF fork? I did a lot of testing >>>> with upstream OVMF, and never ran into this issue. >>> >>> Not really a git tree, but the sources are here: >>> https://build.opensuse.org/package/show/openSUSE:Factory/ovmf >>> >> >> >> Anywhere I can get an actual build? The src rpm only has the sources, >> and the i586 rpm has nothing except >> >> $ rpm -qlp ~/Downloads/ovmf-202002-1.1.i586.rpm >> warning: /home/ardbie01/Downloads/ovmf-202002-1.1.i586.rpm: Header V3 >> RSA/SHA256 Signature, key ID 3dbdc284: NOKEY >> /usr/share/doc/packages/ovmf >> /usr/share/doc/packages/ovmf/README > > Hmmm, it's weird that OBS doesn't list all derived files. > Anyway, the ia32 ovmf is available in > http://download.opensuse.org/tumbleweed/repo/oss/noarch/qemu-ovmf-ia32-202002-1.1.noarch.rpm It indeed does: https://build.opensuse.org/package/binaries/openSUSE:Factory/ovmf/standard Note that the ia32 version is noarch, built on i586. thanks, -- js suse labs
