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| author | Frank van der Linden <fllinden@amazon.com> | 2019-05-22 22:17:45 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-22 08:18:25 +0200 |
| commit | 3e74b3f05abfea7c3c348df9e7ef237c81a1d4c8 (patch) | |
| tree | e33a88ceeb05a7f984d9e19fbf8779377e3a6dea | |
| parent | f4678b7808e7783d67cc02f41f6dca3f158a9a5f (diff) | |
| download | linux-stable-3e74b3f05abfea7c3c348df9e7ef237c81a1d4c8.tar.gz linux-stable-3e74b3f05abfea7c3c348df9e7ef237c81a1d4c8.tar.bz2 linux-stable-3e74b3f05abfea7c3c348df9e7ef237c81a1d4c8.zip | |
x86/CPU/AMD: Don't force the CPB cap when running under a hypervisor
[ Upstream commit 2ac44ab608705948564791ce1d15d43ba81a1e38 ]
For F17h AMD CPUs, the CPB capability ('Core Performance Boost') is forcibly set,
because some versions of that chip incorrectly report that they do not have it.
However, a hypervisor may filter out the CPB capability, for good
reasons. For example, KVM currently does not emulate setting the CPB
bit in MSR_K7_HWCR, and unchecked MSR access errors will be thrown
when trying to set it as a guest:
unchecked MSR access error: WRMSR to 0xc0010015 (tried to write 0x0000000001000011) at rIP: 0xffffffff890638f4 (native_write_msr+0x4/0x20)
Call Trace:
boost_set_msr+0x50/0x80 [acpi_cpufreq]
cpuhp_invoke_callback+0x86/0x560
sort_range+0x20/0x20
cpuhp_thread_fun+0xb0/0x110
smpboot_thread_fn+0xef/0x160
kthread+0x113/0x130
kthread_create_worker_on_cpu+0x70/0x70
ret_from_fork+0x35/0x40
To avoid this issue, don't forcibly set the CPB capability for a CPU
when running under a hypervisor.
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@alien8.de
Cc: jiaxun.yang@flygoat.com
Fixes: 0237199186e7 ("x86/CPU/AMD: Set the CPB bit unconditionally on F17h")
Link: http://lkml.kernel.org/r/20190522221745.GA15789@dev-dsk-fllinden-2c-c1893d73.us-west-2.amazon.com
[ Minor edits to the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index e94e6f16172b..6f2483292de0 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -717,8 +717,11 @@ static void init_amd_zn(struct cpuinfo_x86 *c) { set_cpu_cap(c, X86_FEATURE_ZEN); - /* Fix erratum 1076: CPB feature bit not being set in CPUID. */ - if (!cpu_has(c, X86_FEATURE_CPB)) + /* + * Fix erratum 1076: CPB feature bit not being set in CPUID. + * Always set it, except when running under a hypervisor. + */ + if (!cpu_has(c, X86_FEATURE_HYPERVISOR) && !cpu_has(c, X86_FEATURE_CPB)) set_cpu_cap(c, X86_FEATURE_CPB); } |