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Subject[PATCH v3 4/5] x86/ioapic: Fix lost IOAPIC resource after hot-removal and hotadd
Date
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. It is because
handle_ioapic_add() requests resource 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>
---
drivers/acpi/ioapic.c | 36 ++++++++++++++++++++----------------
1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
index 8ab6d42..ee20111 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);
}
--
1.8.3.1
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