From: David Woodhouse <dwmw@xxxxxxxxxxxx> [ Upstream commit 3d7746bea92530e8695258a3cf3ddec7a135edd6 ] Only the IPI-related functions in the smp_ops should be conditional on the vector callback being available. The rest should still happen: • xen_hvm_smp_prepare_boot_cpu() This function does two things, both of which should still happen if there is no vector callback support. The call to xen_vcpu_setup() for vCPU0 should still happen as it just sets up the vcpu_info for CPU0. That does happen for the secondary vCPUs too, from xen_cpu_up_prepare_hvm(). The second thing it does is call xen_init_spinlocks(), which perhaps counter-intuitively should *also* still be happening in the case without vector callbacks, so that it can clear its local xen_pvspin flag and disable the virt_spin_lock_key accordingly. Checking xen_have_vector_callback in xen_init_spinlocks() itself would affect PV guests, so set the global nopvspin flag in xen_hvm_smp_init() instead, when vector callbacks aren't available. • xen_hvm_smp_prepare_cpus() This does some IPI-related setup by calling xen_smp_intr_init() and xen_init_lock_cpu(), which can be made conditional. And it sets the xen_vcpu_id to XEN_VCPU_ID_INVALID for all possible CPUS, which does need to happen. • xen_smp_cpus_done() This offlines any vCPUs which doesn't fit in the global shared_info page, if separate vcpu_info placement isn't available. That part also needs to happen regardless of vector callback support. • xen_hvm_cpu_die() This doesn't actually do anything other than commin_cpu_die() right right now in the !vector_callback case; all three teardown functions it calls should be no-ops. But to guard against future regressions it's useful to call it anyway, and for it to explicitly check for xen_have_vector_callback before calling those additional functions. Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210106153958.584169-6-dwmw2@xxxxxxxxxxxxx Signed-off-by: Juergen Gross <jgross@xxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/x86/xen/smp_hvm.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/arch/x86/xen/smp_hvm.c b/arch/x86/xen/smp_hvm.c index f5e7db4f82abb..056430a1080bb 100644 --- a/arch/x86/xen/smp_hvm.c +++ b/arch/x86/xen/smp_hvm.c @@ -33,9 +33,11 @@ static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus) int cpu; native_smp_prepare_cpus(max_cpus); - WARN_ON(xen_smp_intr_init(0)); - xen_init_lock_cpu(0); + if (xen_have_vector_callback) { + WARN_ON(xen_smp_intr_init(0)); + xen_init_lock_cpu(0); + } for_each_possible_cpu(cpu) { if (cpu == 0) @@ -50,9 +52,11 @@ static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus) static void xen_hvm_cpu_die(unsigned int cpu) { if (common_cpu_die(cpu) == 0) { - xen_smp_intr_free(cpu); - xen_uninit_lock_cpu(cpu); - xen_teardown_timer(cpu); + if (xen_have_vector_callback) { + xen_smp_intr_free(cpu); + xen_uninit_lock_cpu(cpu); + xen_teardown_timer(cpu); + } } } #else @@ -64,14 +68,17 @@ static void xen_hvm_cpu_die(unsigned int cpu) void __init xen_hvm_smp_init(void) { - if (!xen_have_vector_callback) + smp_ops.smp_prepare_boot_cpu = xen_hvm_smp_prepare_boot_cpu; + smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus; + smp_ops.smp_cpus_done = xen_smp_cpus_done; + smp_ops.cpu_die = xen_hvm_cpu_die; + + if (!xen_have_vector_callback) { + nopvspin = true; return; + } - smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus; smp_ops.smp_send_reschedule = xen_smp_send_reschedule; - smp_ops.cpu_die = xen_hvm_cpu_die; smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi; smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi; - smp_ops.smp_prepare_boot_cpu = xen_hvm_smp_prepare_boot_cpu; - smp_ops.smp_cpus_done = xen_smp_cpus_done; } -- 2.27.0
