x86/ioapic: Fix lost IOAPIC resource after hot-removal and hotadd

IOAPIC resource at 0xfecxxxxx gets lost from /proc/iomem after
hot-removing and then hot-adding the IOAPIC device.

After system boot, in /proc/iomem:

 fec00000-fecfffff : PNP0003:00
   fec00000-fec003ff : IOAPIC 0
   fec01000-fec013ff : IOAPIC 1
   fec40000-fec403ff : IOAPIC 2
   fec80000-fec803ff : IOAPIC 3
   fecc0000-fecc03ff : IOAPIC 4

Then hot-remove IOAPIC 2 and hot-add it again:

 fec00000-fecfffff : PNP0003:00
   fec00000-fec003ff : IOAPIC 0
   fec01000-fec013ff : IOAPIC 1
   fec80000-fec803ff : IOAPIC 3
   fecc0000-fecc03ff : IOAPIC 4

The range at 0xfec40000 is lost from /proc/iomem - which is a bug.

This bug happens because handle_ioapic_add() requests resources from
either PCI config BAR or ACPI "_CRS", not both. But Intel platforms
map the IOxAPIC registers both at the PCI config BAR (called MBAR, dynamic),
and at the ACPI "_CRS" (called ABAR, static). The 0xfecX_YZ00 to 0xfecX_YZFF
range appears in "_CRS" of each IOAPIC device.

Both ranges should be claimed from /proc/iomem for exclusive use.

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bhelgaas@google.com
Cc: helgaas@kernel.org
Cc: linux-acpi@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: rjw@rjwysocki.net
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/1471420837-31003-5-git-send-email-rui.y.wang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 20 insertions, 16 deletions

diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
index 8ab6d426c178..ee201111e063 100644
--- a/drivers/acpi/ioapic.c
+++ b/drivers/acpi/ioapic.c
@@ -97,7 +97,7 @@ static acpi_status handle_ioapic_add(acpi_handle handle, u32 lvl,
         unsigned long long gsi_base;
         struct acpi_pci_ioapic *ioapic;
         struct pci_dev *dev = NULL;
-        struct resource *res = NULL;
+        struct resource *res = NULL, *pci_res = NULL, *crs_res;
         char *type = NULL;
 
         if (!acpi_is_ioapic(handle, &type))
@@ -137,23 +137,28 @@ static acpi_status handle_ioapic_add(acpi_handle handle, u32 lvl,
                 pci_set_master(dev);
                 if (pci_request_region(dev, 0, type))
                         goto exit_disable;
-                res = &dev->resource[0];
+                pci_res = &dev->resource[0];
                 ioapic->pdev = dev;
         } else {
                 pci_dev_put(dev);
                 dev = NULL;
+        }
 
-                res = &ioapic->res;
-                acpi_walk_resources(handle, METHOD_NAME__CRS, setup_res, res);
-                if (res->flags == 0) {
-                        acpi_handle_warn(handle, "failed to get resource\n");
-                        goto exit_free;
-                } else if (request_resource(&iomem_resource, res)) {
-                        acpi_handle_warn(handle, "failed to insert resource\n");
-                        goto exit_free;
-                }
+        crs_res = &ioapic->res;
+        acpi_walk_resources(handle, METHOD_NAME__CRS, setup_res, crs_res);
+        if (crs_res->flags == 0) {
+                acpi_handle_warn(handle, "failed to get resource\n");
+                goto exit_release;
+        } else if (request_resource(&iomem_resource, crs_res)) {
+                acpi_handle_warn(handle, "failed to insert resource\n");
+                goto exit_release;
         }
 
+        /* try pci resource first, then "_CRS" resource */
+        res = pci_res;
+        if (!res || !res->flags)
+                res = crs_res;
+
         if (acpi_register_ioapic(handle, res->start, (u32)gsi_base)) {
                 acpi_handle_warn(handle, "failed to register IOAPIC\n");
                 goto exit_release;
@@ -174,14 +179,13 @@ done:
 exit_release:
         if (dev)
                 pci_release_region(dev, 0);
-        else
-                release_resource(res);
+        if (ioapic->res.flags && ioapic->res.parent)
+                release_resource(&ioapic->res);
 exit_disable:
         if (dev)
                 pci_disable_device(dev);
 exit_put:
         pci_dev_put(dev);
-exit_free:
         kfree(ioapic);
 exit:
         mutex_unlock(&ioapic_list_lock);
@@ -217,9 +221,9 @@ int acpi_ioapic_remove(struct acpi_pci_root *root)
                         pci_release_region(ioapic->pdev, 0);
                         pci_disable_device(ioapic->pdev);
                         pci_dev_put(ioapic->pdev);
-                } else if (ioapic->res.flags && ioapic->res.parent) {
-                        release_resource(&ioapic->res);
                 }
+                if (ioapic->res.flags && ioapic->res.parent)
+                        release_resource(&ioapic->res);
                 list_del(&ioapic->list);
                 kfree(ioapic);
         }