2 files changed, 58 insertions, 33 deletions

diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index 0b31aebd9405..94d05bd6586f 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -188,8 +188,8 @@ extern int mp_find_ioapic_pin(int ioapic, u32 gsi);
 extern u32 mp_pin_to_gsi(int ioapic, int pin);
 extern int mp_map_gsi_to_irq(u32 gsi, unsigned int flags);
 extern void mp_unmap_irq(int irq);
-extern void mp_register_ioapic(int id, u32 address, u32 gsi_base,
-                               struct ioapic_domain_cfg *cfg);
+extern int mp_register_ioapic(int id, u32 address, u32 gsi_base,
+                              struct ioapic_domain_cfg *cfg);
 extern int mp_irqdomain_map(struct irq_domain *domain, unsigned int virq,
                             irq_hw_number_t hwirq);
 extern void mp_irqdomain_unmap(struct irq_domain *domain, unsigned int virq);
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 60f25e88734b..4333a751937d 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3840,20 +3840,6 @@ int mp_find_ioapic_pin(int ioapic, u32 gsi)
         return gsi - gsi_cfg->gsi_base;
 }
 
-static int bad_ioapic(unsigned long address)
-{
-        if (nr_ioapics >= MAX_IO_APICS) {
-                pr_warn("WARNING: Max # of I/O APICs (%d) exceeded (found %d), skipping\n",
-                        MAX_IO_APICS, nr_ioapics);
-                return 1;
-        }
-        if (!address) {
-                pr_warn("WARNING: Bogus (zero) I/O APIC address found in table, skipping!\n");
-                return 1;
-        }
-        return 0;
-}
-
 static int bad_ioapic_register(int idx)
 {
         union IO_APIC_reg_00 reg_00;
@@ -3873,29 +3859,51 @@ static int bad_ioapic_register(int idx)
         return 0;
 }
 
-void mp_register_ioapic(int id, u32 address, u32 gsi_base,
-                        struct ioapic_domain_cfg *cfg)
+static int find_free_ioapic_entry(void)
+{
+        return nr_ioapics;
+}
+
+/**
+ * mp_register_ioapic - Register an IOAPIC device
+ * @id:         hardware IOAPIC ID
+ * @address:    physical address of IOAPIC register area
+ * @gsi_base:   base of GSI associated with the IOAPIC
+ * @cfg:        configuration information for the IOAPIC
+ */
+int mp_register_ioapic(int id, u32 address, u32 gsi_base,
+                       struct ioapic_domain_cfg *cfg)
 {
-        int idx = 0;
-        int entries;
         struct mp_ioapic_gsi *gsi_cfg;
+        int idx, ioapic, entries;
+        u32 gsi_end;
 
-        if (bad_ioapic(address))
-                return;
+        if (!address) {
+                pr_warn("Bogus (zero) I/O APIC address found, skipping!\n");
+                return -EINVAL;
+        }
+        for_each_ioapic(ioapic)
+                if (ioapics[ioapic].mp_config.apicaddr == address) {
+                        pr_warn("address 0x%x conflicts with IOAPIC%d\n",
+                                address, ioapic);
+                        return -EEXIST;
+                }
 
-        idx = nr_ioapics;
+        idx = find_free_ioapic_entry();
+        if (idx >= MAX_IO_APICS) {
+                pr_warn("Max # of I/O APICs (%d) exceeded (found %d), skipping\n",
+                        MAX_IO_APICS, idx);
+                return -ENOSPC;
+        }
 
         ioapics[idx].mp_config.type = MP_IOAPIC;
         ioapics[idx].mp_config.flags = MPC_APIC_USABLE;
         ioapics[idx].mp_config.apicaddr = address;
-        ioapics[idx].irqdomain = NULL;
-        ioapics[idx].irqdomain_cfg = *cfg;
 
         set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address);
-
         if (bad_ioapic_register(idx)) {
                 clear_fixmap(FIX_IO_APIC_BASE_0 + idx);
-                return;
+                return -ENODEV;
         }
 
         ioapics[idx].mp_config.apicid = io_apic_unique_id(idx, id);
@@ -3906,24 +3914,41 @@ void mp_register_ioapic(int id, u32 address, u32 gsi_base,
          * and to prevent reprogramming of IOAPIC pins (PCI GSIs).
          */
         entries = io_apic_get_redir_entries(idx);
+        gsi_end = gsi_base + entries - 1;
+        for_each_ioapic(ioapic) {
+                gsi_cfg = mp_ioapic_gsi_routing(ioapic);
+                if ((gsi_base >= gsi_cfg->gsi_base &&
+                     gsi_base <= gsi_cfg->gsi_end) ||
+                    (gsi_end >= gsi_cfg->gsi_base &&
+                     gsi_end <= gsi_cfg->gsi_end)) {
+                        pr_warn("GSI range [%u-%u] for new IOAPIC conflicts with GSI[%u-%u]\n",
+                                gsi_base, gsi_end,
+                                gsi_cfg->gsi_base, gsi_cfg->gsi_end);
+                        clear_fixmap(FIX_IO_APIC_BASE_0 + idx);
+                        return -ENOSPC;
+                }
+        }
         gsi_cfg = mp_ioapic_gsi_routing(idx);
         gsi_cfg->gsi_base = gsi_base;
-        gsi_cfg->gsi_end = gsi_base + entries - 1;
+        gsi_cfg->gsi_end = gsi_end;
 
-        /*
-         * The number of IO-APIC IRQ registers (== #pins):
-         */
-        ioapics[idx].nr_registers = entries;
+        ioapics[idx].irqdomain = NULL;
+        ioapics[idx].irqdomain_cfg = *cfg;
 
         if (gsi_cfg->gsi_end >= gsi_top)
                 gsi_top = gsi_cfg->gsi_end + 1;
+        if (nr_ioapics <= idx)
+                nr_ioapics = idx + 1;
+
+        /* Set nr_registers to mark entry present */
+        ioapics[idx].nr_registers = entries;
 
         pr_info("IOAPIC[%d]: apic_id %d, version %d, address 0x%x, GSI %d-%d\n",
                 idx, mpc_ioapic_id(idx),
                 mpc_ioapic_ver(idx), mpc_ioapic_addr(idx),
                 gsi_cfg->gsi_base, gsi_cfg->gsi_end);
 
-        nr_ioapics++;
+        return 0;
 }
 
 int mp_irqdomain_map(struct irq_domain *domain, unsigned int virq,