genirq/msi, x86/vector: Prevent reservation mode for non maskable MSI

[sfrench/cifs-2.6.git] / kernel / irq / msi.c

diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 9ba9543311715313d63f8cba7fa39b7b1999bcae..2f3c4f5382cc6bad8daf528146cf613d9a1ac3e6 100644 (file)
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -339,11 +339,38 @@ int msi_domain_populate_irqs(struct irq_domain *domain, struct device *dev,
        return ret;
 }
 
-static bool msi_check_reservation_mode(struct msi_domain_info *info)
+/*
+ * Carefully check whether the device can use reservation mode. If
+ * reservation mode is enabled then the early activation will assign a
+ * dummy vector to the device. If the PCI/MSI device does not support
+ * masking of the entry then this can result in spurious interrupts when
+ * the device driver is not absolutely careful. But even then a malfunction
+ * of the hardware could result in a spurious interrupt on the dummy vector
+ * and render the device unusable. If the entry can be masked then the core
+ * logic will prevent the spurious interrupt and reservation mode can be
+ * used. For now reservation mode is restricted to PCI/MSI.
+ */
+static bool msi_check_reservation_mode(struct irq_domain *domain,
+                                      struct msi_domain_info *info,
+                                      struct device *dev)
 {
+       struct msi_desc *desc;
+
+       if (domain->bus_token != DOMAIN_BUS_PCI_MSI)
+               return false;
+
        if (!(info->flags & MSI_FLAG_MUST_REACTIVATE))
                return false;
-       return true;
+
+       if (IS_ENABLED(CONFIG_PCI_MSI) && pci_msi_ignore_mask)
+               return false;
+
+       /*
+        * Checking the first MSI descriptor is sufficient. MSIX supports
+        * masking and MSI does so when the maskbit is set.
+        */
+       desc = first_msi_entry(dev);
+       return desc->msi_attrib.is_msix || desc->msi_attrib.maskbit;
 }
 
 /**
@@ -394,7 +421,7 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
        if (ops->msi_finish)
                ops->msi_finish(&arg, 0);
 
-       can_reserve = msi_check_reservation_mode(info);
+       can_reserve = msi_check_reservation_mode(domain, info, dev);
 
        for_each_msi_entry(desc, dev) {
                virq = desc->irq;
@@ -412,7 +439,9 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
                        continue;
 
                irq_data = irq_domain_get_irq_data(domain, desc->irq);
-               ret = irq_domain_activate_irq(irq_data, true);
+               if (!can_reserve)
+                       irqd_clr_can_reserve(irq_data);
+               ret = irq_domain_activate_irq(irq_data, can_reserve);
                if (ret)
                        goto cleanup;
        }