Attachment 132946 Details for Bug 101901 – proposed fix

[patch] proposed fix

0001-drm-i915-Handle-msr-read-failure-gracefully.patch (text/plain), 2.25 KB, created by krisman on 2017-07-25 06:42:54 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: krisman

Created: 2017-07-25 06:42:54 UTC

Size: 2.25 KB

patch

obsolete

>From f45becc18eb0f1e89bfdfd53ff277f2c68d97c12 Mon Sep 17 00:00:00 2001
>From: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
>Date: Tue, 25 Jul 2017 03:19:50 -0300
>Subject: [PATCH] drm/i915: Handle msr read failure gracefully
>
>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
>
>Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101901
>Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
>---
> drivers/gpu/drm/i915/i915_debugfs.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
>index c25f42c60d61..770b2846fed9 100644
>--- a/drivers/gpu/drm/i915/i915_debugfs.c
>+++ b/drivers/gpu/drm/i915/i915_debugfs.c
>@@ -2791,7 +2791,11 @@ static int i915_energy_uJ(struct seq_file *m, void *data)
> 
> 	intel_runtime_pm_get(dev_priv);
> 
>-	rdmsrl(MSR_RAPL_POWER_UNIT, power);
>+	if (rdmsrl_safe(MSR_RAPL_POWER_UNIT, &power)) {
>+		intel_runtime_pm_put(dev_priv);
>+		return -ENODEV;
>+	}
>+
> 	power = (power & 0x1f00) >> 8;
> 	units = 1000000 / (1 << power); /* convert to uJ */
> 	power = I915_READ(MCH_SECP_NRG_STTS);
>-- 
>2.11.0
>

Actions: View | Splinter Review

Attachments on bug 101901: 132946

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.