‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Friday, January 11, 2019 8:59 AM, Peter Zijlstra <pet...@infradead.org> wrote:
> On Fri, Jan 11, 2019 at 01:37:50PM +0000, Esme wrote: > > > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > > On Friday, January 11, 2019 5:02 AM, Peter Zijlstra pet...@infradead.org > > wrote: > > > > > On Thu, Jan 10, 2019 at 11:21:16PM +0000, Esme wrote: > > > > > > > Attached is a fairly small C repro I did not see any references to > > > > this possible flaw (unchecked MSR access) in relation to > > > > __NR_perf_event_open > > > > Attached is the config directly extracted from proc. This is the call > > > > stack in relation to the MSR access error (5.0.0-rc1+), I get a very > > > > similar stack running this test case on a stock Ubuntu > > > > "4.18.0-11-generic" (pasted after this one). > > > > > > > -- Esme > > > > [ 70.228744] unchecked MSR access error: WRMSR to 0xc0010000 (tried to > > > > write 0x0000020000130076) at rIP: 0xffffffff812dde28 > > > > (native_write_msr+0x8/0x30) > > > > > > That's K7_EVNTSEL0. What kind of hardware are you running this on? > > > > QEMU emulator version 3.0.93 (v3.1.0-rc3-dirty) > > [ 0.000000] DMI: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > > rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 > > [ 0.000000] Linux version 4.18.0-11-generic (buildd@lcy01-amd64-027) (gcc > > version 8.2.0 (Ubuntu 8.2.0-7ubuntu1)) #12-Ubuntu SMP Tue Oct 23 19:22:37 > > UTC 2018 (Ubuntu 4.18.0-11.12-generic 4.18.12) > > [ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.18.0-11-generic > > root=UUID=3a43ccb9-a433-4296-8dc5-0443f2a32128 ro quiet splash vt.handoff=1 > > [ 0.000000] KERNEL supported cpus: > > [ 0.000000] Intel GenuineIntel > > [ 0.000000] AMD AuthenticAMD > > [ 0.000000] Centaur CentaurHauls > > [ 0.000000] random: get_random_u32 called from bsp_init_amd+0x205/0x2a0 > > with crng_init=0 > > [ 0.000000] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point > > registers' > > [ 0.000000] x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers' > > [ 0.000000] x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers' > > [ 0.000000] x86/fpu: xstate_offset[2]: 576, xstate_sizes[2]: 256 > > [ 0.000000] x86/fpu: Enabled xstate features 0x7, context size is 832 > > bytes, using 'standard' format. > > Feh, then you get to figure out how the heck it passes > check_hw_exists(). > > Stupid virt crap again. I see, I'm busy most of the day, I do have some bare metal hosts I'm going to update with -current. Do you have any suggested kernel flags to use for the build? If it's specific to virt, I might just toss it into the cloud ;) and see what happens, later. /Best Esme
