ACK/cmnt: [SRU][Xenial][PATCH] x86/speculation: Remove redundant arch_smt_update() invocation
Kleber Souza
kleber.souza at canonical.com
Wed Jun 26 16:44:19 UTC 2019
On 6/13/19 12:56 PM, Juerg Haefliger wrote:
> From: Zhenzhong Duan <zhenzhong.duan at oracle.com>
>
> With commit a74cfffb03b7 ("x86/speculation: Rework SMT state change"),
> arch_smt_update() is invoked from each individual CPU hotplug function.
>
> Therefore the extra arch_smt_update() call in the sysfs SMT control is
> redundant.
>
> Fixes: a74cfffb03b7 ("x86/speculation: Rework SMT state change")
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan at oracle.com>
> Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
> Cc: <konrad.wilk at oracle.com>
> Cc: <dwmw at amazon.co.uk>
> Cc: <bp at suse.de>
> Cc: <srinivas.eeda at oracle.com>
> Cc: <peterz at infradead.org>
> Cc: <hpa at zytor.com>
> Link: https://lkml.kernel.org/r/e2e064f2-e8ef-42ca-bf4f-76b612964752@default
>
> CVE-2018-12126
> CVE-2018-12127
> CVE-2018-12130
>
> (cherry picked from commit 34d66caf251df91ff27b24a3a786810d29989eca)
> Signed-off-by: Juerg Haefliger <juergh at canonical.com>
Juerg,
is this needed for newer series as well?
Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>
Thank you,
Kleber
> ---
> kernel/cpu.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index 5d48161476a1..d9465123f7ec 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -896,10 +896,8 @@ static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
> */
> cpuhp_offline_cpu_device(cpu);
> }
> - if (!ret) {
> + if (!ret)
> cpu_smt_control = ctrlval;
> - arch_smt_update();
> - }
> cpu_maps_update_done();
> return ret;
> }
> @@ -910,7 +908,6 @@ static int cpuhp_smt_enable(void)
>
> cpu_maps_update_begin();
> cpu_smt_control = CPU_SMT_ENABLED;
> - arch_smt_update();
> for_each_present_cpu(cpu) {
> /* Skip online CPUs and CPUs on offline nodes */
> if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
>
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