From 65ac3a4fee03ade83c62644f600a3fc70754b263 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 13 Feb 2024 10:12:06 +0000 Subject: [PATCH] irqchip/gic-v3-its: Fix GICv4.1 VPE affinity update commit af9acbfc2c4b72c378d0b9a2ee023ed01055d3e2 upstream. When updating the affinity of a VPE, the VMOVP command is currently skipped if the two CPUs are part of the same VPE affinity. But this is wrong, as the doorbell corresponding to this VPE is still delivered on the 'old' CPU, which screws up the balancing. Furthermore, offlining that 'old' CPU results in doorbell interrupts generated for this VPE being discarded. The harsh reality is that VMOVP cannot be elided when a set_affinity() request occurs. It needs to be obeyed, and if an optimisation is to be made, it is at the point where the affinity change request is made (such as in KVM). Drop the VMOVP elision altogether, and only use the vpe_table_mask to try and stay within the same ITS affinity group if at all possible. Fixes: dd3f050a216e (irqchip/gic-v4.1: Implement the v4.1 flavour of VMOVP) Reported-by: Kunkun Jiang Signed-off-by: Marc Zyngier Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240213101206.2137483-4-maz@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/irqchip/irq-gic-v3-its.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 39f2e7f85d70..3632c92cd183 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -3826,8 +3826,9 @@ static int its_vpe_set_affinity(struct irq_data *d, bool force) { struct its_vpe *vpe = irq_data_get_irq_chip_data(d); - int from, cpu = cpumask_first(mask_val); + struct cpumask common, *table_mask; unsigned long flags; + int from, cpu; /* * Changing affinity is mega expensive, so let's be as lazy as @@ -3843,19 +3844,22 @@ static int its_vpe_set_affinity(struct irq_data *d, * taken on any vLPI handling path that evaluates vpe->col_idx. */ from = vpe_to_cpuid_lock(vpe, &flags); + table_mask = gic_data_rdist_cpu(from)->vpe_table_mask; + + /* + * If we are offered another CPU in the same GICv4.1 ITS + * affinity, pick this one. Otherwise, any CPU will do. + */ + if (table_mask && cpumask_and(&common, mask_val, table_mask)) + cpu = cpumask_test_cpu(from, &common) ? from : cpumask_first(&common); + else + cpu = cpumask_first(mask_val); + if (from == cpu) goto out; vpe->col_idx = cpu; - /* - * GICv4.1 allows us to skip VMOVP if moving to a cpu whose RD - * is sharing its VPE table with the current one. - */ - if (gic_data_rdist_cpu(cpu)->vpe_table_mask && - cpumask_test_cpu(from, gic_data_rdist_cpu(cpu)->vpe_table_mask)) - goto out; - its_send_vmovp(vpe); its_vpe_db_proxy_move(vpe, from, cpu);