Drivers: hv: vmbus: Don't assign VMbus channel interrupts to isolated CPUs

When initially assigning a VMbus channel interrupt to a CPU, don’t choose
a managed IRQ isolated CPU (as specified on the kernel boot line with
parameter 'isolcpus=managed_irq,<#cpu>'). Also, when using sysfs to change
the CPU that a VMbus channel will interrupt, don't allow changing to a
managed IRQ isolated CPU.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1653637439-23060-1-git-send-email-ssengar@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index b60f134..280b529 100644 (file)
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -21,6 +21,7 @@
 #include <linux/cpu.h>
 #include <linux/hyperv.h>
 #include <asm/mshyperv.h>
+#include <linux/sched/isolation.h>
 
 #include "hyperv_vmbus.h"
 
@@ -728,16 +729,20 @@ static void init_vp_index(struct vmbus_channel *channel)
        u32 i, ncpu = num_online_cpus();
        cpumask_var_t available_mask;
        struct cpumask *allocated_mask;
+       const struct cpumask *hk_mask = housekeeping_cpumask(HK_TYPE_MANAGED_IRQ);
        u32 target_cpu;
        int numa_node;
 
        if (!perf_chn ||
-           !alloc_cpumask_var(&available_mask, GFP_KERNEL)) {
+           !alloc_cpumask_var(&available_mask, GFP_KERNEL) ||
+           cpumask_empty(hk_mask)) {
                /*
                 * If the channel is not a performance critical
                 * channel, bind it to VMBUS_CONNECT_CPU.
                 * In case alloc_cpumask_var() fails, bind it to
                 * VMBUS_CONNECT_CPU.
+                * If all the cpus are isolated, bind it to
+                * VMBUS_CONNECT_CPU.
                 */
                channel->target_cpu = VMBUS_CONNECT_CPU;
                if (perf_chn)
@@ -758,17 +763,19 @@ static void init_vp_index(struct vmbus_channel *channel)
                }
                allocated_mask = &hv_context.hv_numa_map[numa_node];
 
-               if (cpumask_equal(allocated_mask, cpumask_of_node(numa_node))) {
+retry:
+               cpumask_xor(available_mask, allocated_mask, cpumask_of_node(numa_node));
+               cpumask_and(available_mask, available_mask, hk_mask);
+
+               if (cpumask_empty(available_mask)) {
                        /*
                         * We have cycled through all the CPUs in the node;
                         * reset the allocated map.
                         */
                        cpumask_clear(allocated_mask);
+                       goto retry;
                }
 
-               cpumask_xor(available_mask, allocated_mask,
-                           cpumask_of_node(numa_node));
-
                target_cpu = cpumask_first(available_mask);
                cpumask_set_cpu(target_cpu, allocated_mask);
 

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 714d549..547ae33 100644 (file)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -21,6 +21,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/clockchips.h>
 #include <linux/cpu.h>
+#include <linux/sched/isolation.h>
 #include <linux/sched/task_stack.h>
 
 #include <linux/delay.h>
@@ -1770,6 +1771,9 @@ static ssize_t target_cpu_store(struct vmbus_channel *channel,
        if (target_cpu >= nr_cpumask_bits)
                return -EINVAL;
 
+       if (!cpumask_test_cpu(target_cpu, housekeeping_cpumask(HK_TYPE_MANAGED_IRQ)))
+               return -EINVAL;
+
        /* No CPUs should come up or down during this. */
        cpus_read_lock();