x86/hyperv: Fix usage of cpu_online_mask to get valid cpu

Accessing cpu_online_mask here is problematic because the cpus read lock
is not held in this context.

However, cpu_online_mask isn't needed here since the effective affinity
mask is guaranteed to be valid in this callback. So, just use
cpumask_first() to get the cpu instead of ANDing it with cpus_online_mask
unnecessarily.

Fixes: e39397d1fd68 ("x86/hyperv: implement an MSI domain for root partition")
Reported-by: Michael Kelley <mhklinux@outlook.com>
Closes: https://lore.kernel.org/linux-hyperv/SN6PR02MB4157639630F8AD2D8FD8F52FD475A@SN6PR02MB4157.namprd02.prod.outlook.com/
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1751582677-30930-4-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1751582677-30930-4-git-send-email-nunodasneves@linux.microsoft.com>

diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index f7627bc8fe4953e6222146082d51bc03dcbab46a..de883ac76445bd934d9e0e5b76227d8ba6425569 100644 (file)
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -193,7 +193,6 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
        struct pci_dev *dev;
        struct hv_interrupt_entry out_entry, *stored_entry;
        struct irq_cfg *cfg = irqd_cfg(data);
-       const cpumask_t *affinity;
        int cpu;
        u64 status;
 
@@ -205,8 +204,7 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
                return;
        }
 
-       affinity = irq_data_get_effective_affinity_mask(data);
-       cpu = cpumask_first_and(affinity, cpu_online_mask);
+       cpu = cpumask_first(irq_data_get_effective_affinity_mask(data));
 
        if (data->chip_data) {
                /*