From e7c4e36c447daca2b7df49024f6bf230871cb155 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Wed, 24 Jan 2018 14:23:34 +0100 Subject: [PATCH] x86/hyperv: Redirect reenlightment notifications on CPU offlining MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit It is very unlikely for CPUs to get offlined when running on Hyper-V as there is a protection in the vmbus module which prevents it when the guest has any VMBus devices assigned. This, however, may change in future if an option to reassign an already active channel will be added. It is also possible to run without any Hyper-V devices or to have a CPU with no assigned channels. Reassign reenlightenment notifications to some other active CPU when the CPU which is assigned to them goes offline. Signed-off-by: Vitaly Kuznetsov Signed-off-by: Thomas Gleixner Reviewed-by: Thomas Gleixner Cc: Stephen Hemminger Cc: kvm@vger.kernel.org Cc: Radim Krčmář Cc: Haiyang Zhang Cc: "Michael Kelley (EOSG)" Cc: Roman Kagan Cc: Andy Lutomirski Cc: devel@linuxdriverproject.org Cc: Paolo Bonzini Cc: "K. Y. Srinivasan" Cc: Cathy Avery Cc: Mohammed Gamal Link: https://lkml.kernel.org/r/20180124132337.30138-5-vkuznets@redhat.com --- arch/x86/hyperv/hv_init.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 712ac40081f7..e4377e2f2a10 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -191,6 +191,26 @@ void clear_hv_tscchange_cb(void) } EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb); +static int hv_cpu_die(unsigned int cpu) +{ + struct hv_reenlightenment_control re_ctrl; + unsigned int new_cpu; + + if (hv_reenlightenment_cb == NULL) + return 0; + + rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); + if (re_ctrl.target_vp == hv_vp_index[cpu]) { + /* Reassign to some other online CPU */ + new_cpu = cpumask_any_but(cpu_online_mask, cpu); + + re_ctrl.target_vp = hv_vp_index[new_cpu]; + wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); + } + + return 0; +} + /* * This function is to be invoked early in the boot sequence after the * hypervisor has been detected. @@ -220,7 +240,7 @@ void hyperv_init(void) return; if (cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online", - hv_cpu_init, NULL) < 0) + hv_cpu_init, hv_cpu_die) < 0) goto free_vp_index; /* -- 2.11.4.GIT