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When reading the i915_energy_uJ debugfs file, it tries to fetch
MSR_RAPL_POWER_UNIT, which might not be available, like in a vm
environment, causing the exception shown below.
We can easily prevent it by doing a rdmsrl_safe read instead, which will
handle the exception, allowing us to abort the debugfs file read.
This was caught by the new igt@debugfs_test@read_all_entries testcase in
the CI.
unchecked MSR access error: RDMSR from 0x606 at rIP:0xffffffffa0078f66
(i915_energy_uJ+0x36/0xb0 [i915])
Call Trace:
seq_read+0xdc/0x3a0
full_proxy_read+0x4f/0x70
__vfs_read+0x23/0x120
? putname+0x4f/0x60
? rcu_read_lock_sched_held+0x75/0x80
? entry_SYSCALL_64_fastpath+0x5/0xb1
vfs_read+0xa0/0x150
SyS_read+0x44/0xb0
entry_SYSCALL_64_fastpath+0x1c/0xb1
RIP: 0033:0x7f1f5e9f4500
RSP: 002b:00007ffc77e65cf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: ffffffff8146e003 RCX: 00007f1f5e9f4500
RDX: 0000000000000200 RSI: 00007ffc77e65d10 RDI: 0000000000000006
RBP: ffffc900007abf88 R08: 0000000001eaff20 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000006 R14: 0000000000000005 R15: 0000000001eb94db
? __this_cpu_preempt_check+0x13/0x20
v2:
- Drop unsigned long long cast and improve calculation (Chris)
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101901
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/87o9s7zrx3.fsf@dilma.collabora.co.uk
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.